tag:blogger.com,1999:blog-47561372343240040762024-03-14T05:24:46.408-04:00RocketSparrowSpivhttp://www.blogger.com/profile/10510295596753094109noreply@blogger.comBlogger94125tag:blogger.com,1999:blog-4756137234324004076.post-18297372664297493612017-01-28T02:24:00.002-05:002017-01-28T02:26:07.871-05:00How I made a better Celestron AVXI'm in no position to complain, I got my AVX for jellybeans because a surplus shop thought it was broken. But if I had paid full price I would not think well of the performance of the mount right out of the box.<br />
<div>
<br /></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://2.bp.blogspot.com/-Iu6IYxDS_w4/WIw7yriLw1I/AAAAAAAA56A/sKgbpbF1o9MmXhDPem9hEwiibd98Zi0FwCEw/s1600/DSCF1120.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="https://2.bp.blogspot.com/-Iu6IYxDS_w4/WIw7yriLw1I/AAAAAAAA56A/sKgbpbF1o9MmXhDPem9hEwiibd98Zi0FwCEw/s320/DSCF1120.jpg" width="301" /></a></div>
<div>
<br />
<div>
<br /></div>
<div>
It isn't difficult to achieve subs of a minute or two, but:</div>
<div>
<ul>
<li>Glitches happen. I've reloaded my firmware a couple times for the occasional "bootloader error."</li>
<li>It's basically impossible to balance, as the mount is so "sticky." Other people call this stiff, but having worked on industrial machinery I know that's bollocks.</li>
<li>The motors are clearly struggling. Some of this may be my fault, having tightened everything down to minimize backlash.</li>
<li>There's some roughness in RA. I found out why.</li>
</ul>
<div>
So I disassembled the thing completely, did some things, and then I was able to take 15 minute subs. Here's what I found/did...</div>
</div>
<div>
<br /></div>
<div>
Step one, remove the dovetail clamp:</div>
<div class="separator" style="clear: both; text-align: center;">
</div>
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://1.bp.blogspot.com/-0-kELbbHt4w/WIw7y4CUfYI/AAAAAAAA55A/IvGqp-y6puEwIFVwORefokWt3y0BWXXNACLcB/s1600/DSCF1121.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="270" src="https://1.bp.blogspot.com/-0-kELbbHt4w/WIw7y4CUfYI/AAAAAAAA55A/IvGqp-y6puEwIFVwORefokWt3y0BWXXNACLcB/s320/DSCF1121.jpg" width="320" /></a></div>
<div class="separator" style="clear: both; text-align: center;">
<br /></div>
<div class="separator" style="clear: both; text-align: left;">
First discovery. Think these are assembled in a precision lab? Noooot so much. Yes, that's a rock. Just, randomly dropped in to this thing that's supposed to be accurate to a few arc-seconds. Is it anywhere that would be a problem? No, but it's not a good start.</div>
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://4.bp.blogspot.com/-U8nK9A32vc8/WIw7yz72O2I/AAAAAAAA56A/Kj5_PDIQ8m8Kut_G7BdsPHubKaZWj-9tQCEw/s1600/DSCF1123.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="285" src="https://4.bp.blogspot.com/-U8nK9A32vc8/WIw7yz72O2I/AAAAAAAA56A/Kj5_PDIQ8m8Kut_G7BdsPHubKaZWj-9tQCEw/s320/DSCF1123.jpg" width="320" /></a></div>
<div class="separator" style="clear: both; text-align: center;">
</div>
<br />
<div class="separator" style="clear: both; text-align: center;">
</div>
I unbolted the DEC assembly from the RA axis, it's just two bolts:<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://1.bp.blogspot.com/-C6ctW-U9x2g/WIw72Z6pqkI/AAAAAAAA56I/UQDyDAy5b4MLHELs1Ri-zeaiWdSXJIbLwCEw/s1600/DSCF1126.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="274" src="https://1.bp.blogspot.com/-C6ctW-U9x2g/WIw72Z6pqkI/AAAAAAAA56I/UQDyDAy5b4MLHELs1Ri-zeaiWdSXJIbLwCEw/s320/DSCF1126.jpg" width="320" /></a></div>
<div class="separator" style="clear: both; text-align: center;">
<br /></div>
<div class="separator" style="clear: both; text-align: left;">
and disassembled the worm gear system. This all looked reasonably good, other than just having way too much grease on it. The grease is what makes the AVX so sticky. You want grease, especially where the worm meets the DEC drive, but they've overdone it quite a bit.</div>
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://3.bp.blogspot.com/-UMZPmV_yqYI/WIw71Y_xZrI/AAAAAAAA56I/S6uJ-0ZctFcj3HmvKE9cLPPXfrcOLE-WgCEw/s1600/DSCF1128.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="280" src="https://3.bp.blogspot.com/-UMZPmV_yqYI/WIw71Y_xZrI/AAAAAAAA56I/S6uJ-0ZctFcj3HmvKE9cLPPXfrcOLE-WgCEw/s320/DSCF1128.jpg" width="320" /></a></div>
<div class="separator" style="clear: both; text-align: center;">
<br /></div>
<div class="separator" style="clear: both; text-align: left;">
To disassembled the DEC rotating assembly you'll need to loosen two set screws through a small access hole on the back:</div>
<div class="separator" style="clear: both; text-align: center;">
</div>
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://1.bp.blogspot.com/-f2GOF_y_fZI/WIw7051PV2I/AAAAAAAA55E/h_GKYrAACkokMUZsMLM1x3mYvoFm-m90gCLcB/s1600/DSCF1136.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="287" src="https://1.bp.blogspot.com/-f2GOF_y_fZI/WIw7051PV2I/AAAAAAAA55E/h_GKYrAACkokMUZsMLM1x3mYvoFm-m90gCLcB/s320/DSCF1136.jpg" width="320" /></a></div>
<div class="separator" style="clear: both; text-align: center;">
<br /></div>
<div class="separator" style="clear: both; text-align: left;">
And then unscrew the tensioning...thing...from the assembly. I happened to have this tool for taking watches apart that worked well for this. I had to get creative later on though.</div>
<div class="separator" style="clear: both; text-align: center;">
<br /></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://3.bp.blogspot.com/-b3s8rE7j-VA/WIw72ilW8lI/AAAAAAAA56I/FerFnagK8ac5RnDFJB60j25ese15Bpj2ACEw/s1600/DSCF1137.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="270" src="https://3.bp.blogspot.com/-b3s8rE7j-VA/WIw72ilW8lI/AAAAAAAA56I/FerFnagK8ac5RnDFJB60j25ese15Bpj2ACEw/s320/DSCF1137.jpg" width="320" /></a></div>
<div class="separator" style="clear: both; text-align: center;">
<br /></div>
Assembly apart- as you can see there are no bearings in this portion of the mount. It would be nice if they were there, but it's actually not too bad here. The mating surfaces have been turned nicely on a lathe, and the tensioning ring tightens against a pair of large nylon washers. Would bearings be better? Of course. But it's probably not as bad as many make it out to be.<br />
<div class="separator" style="clear: both; text-align: center;">
</div>
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://1.bp.blogspot.com/-QjtSq4JuG_Q/WIw74rUrVTI/AAAAAAAA55U/WaJE3PVFjFEorlFGzrKHuudWB6z01_BLgCLcB/s1600/DSCF1140.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="241" src="https://1.bp.blogspot.com/-QjtSq4JuG_Q/WIw74rUrVTI/AAAAAAAA55U/WaJE3PVFjFEorlFGzrKHuudWB6z01_BLgCLcB/s320/DSCF1140.jpg" width="320" /></a></div>
<br />
<div class="separator" style="clear: both; text-align: center;">
</div>
Pulling the RA apart was a bit more trouble. I had a bicycle tool that worked well for taking the fancy orange covers off as well as the two tensioning rings:<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://1.bp.blogspot.com/-xZxxDQQQse0/WIw76O3NzAI/AAAAAAAA56I/bXSNeoCYWpcoXs5JqeOZGYwUDi_2BdV4ACEw/s1600/DSCF1148.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="213" src="https://1.bp.blogspot.com/-xZxxDQQQse0/WIw76O3NzAI/AAAAAAAA56I/bXSNeoCYWpcoXs5JqeOZGYwUDi_2BdV4ACEw/s320/DSCF1148.jpg" width="320" /></a></div>
<div class="separator" style="clear: both; text-align: center;">
<br /></div>
<div class="separator" style="clear: both; text-align: left;">
To remove the assembly you need to loosen these three set screws; they hold a thin metal plate and nylon washer against the altitude adjustment. Once those are loose you can tap the threaded pipe out and free the RA:</div>
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://2.bp.blogspot.com/-ZzoUMaApPto/WIw75byFHrI/AAAAAAAA56I/hY5oczi43-U47CRdBi7ksw8YDu1bEjgrQCEw/s1600/DSCF1151.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="291" src="https://2.bp.blogspot.com/-ZzoUMaApPto/WIw75byFHrI/AAAAAAAA56I/hY5oczi43-U47CRdBi7ksw8YDu1bEjgrQCEw/s320/DSCF1151.jpg" width="320" /></a></div>
<div class="separator" style="clear: both; text-align: center;">
<br /></div>
<div class="separator" style="clear: both; text-align: left;">
Unfortunately my fancy tool wouldn't work on the RA tensioning ring. I had to improvise. Don't tell anyone where you learned this trick, but a couple of allen keys poked in to the holes and a pair of pliers will either save the day or ruin something. Thankfully my day worked out well:</div>
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://4.bp.blogspot.com/-b7kt0err4yA/WIw77GmorCI/AAAAAAAA56I/8uIwKJW9GnIVN0UCs3kuHAI7_6z4Z1JPACEw/s1600/DSCF1158.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="249" src="https://4.bp.blogspot.com/-b7kt0err4yA/WIw77GmorCI/AAAAAAAA56I/8uIwKJW9GnIVN0UCs3kuHAI7_6z4Z1JPACEw/s320/DSCF1158.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Note: there are THREE set screws on the RA axis to loosen</td></tr>
</tbody></table>
<div class="separator" style="clear: both; text-align: left;">
That's everything apart. And, well, oh dear...</div>
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://4.bp.blogspot.com/-YKlRrYvZp0U/WIw771juoJI/AAAAAAAA56I/5UEp1CWKivohoyLFWCN1Z_Wxj0P5NYhAACEw/s1600/DSCF1161.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="227" src="https://4.bp.blogspot.com/-YKlRrYvZp0U/WIw771juoJI/AAAAAAAA56I/5UEp1CWKivohoyLFWCN1Z_Wxj0P5NYhAACEw/s320/DSCF1161.jpg" width="320" /></a></div>
<div class="separator" style="clear: both; text-align: center;">
</div>
<br />
<div class="separator" style="clear: both; text-align: center;">
</div>
Ok, one side uses a thrust bearing that gets tension against another machine surface. There are better options for this, sure, but this is probably fine too...<br />
<div class="separator" style="clear: both; text-align: center;">
</div>
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://1.bp.blogspot.com/-uvp7Ay60JGM/WIw773i0n2I/AAAAAAAA55o/YGGcWhZtZ8cAdxZHa9EkTAt4_v09aUk7gCLcB/s1600/DSCF1164.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="245" src="https://1.bp.blogspot.com/-uvp7Ay60JGM/WIw773i0n2I/AAAAAAAA55o/YGGcWhZtZ8cAdxZHa9EkTAt4_v09aUk7gCLcB/s320/DSCF1164.jpg" width="320" /></a></div>
<br />
<div class="separator" style="clear: both; text-align: center;">
</div>
This, on the other hand, feels like amateur hour. The side closest to the DEC is a regular radial bearing, which of course you shouldn't tension. So their solution was to mash it against another nylon washer. This is a terrible idea. Both the inner and outer rings of that bearing are pressed against the same surface.<br />
<div class="separator" style="clear: both; text-align: center;">
</div>
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://1.bp.blogspot.com/-z1Qwm7bZppM/WIw7-yiZMWI/AAAAAAAA55w/NIkZOHHSw10UCr1t3mdWTc2k5x3msKpJwCLcB/s1600/DSCF1185.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="279" src="https://1.bp.blogspot.com/-z1Qwm7bZppM/WIw7-yiZMWI/AAAAAAAA55w/NIkZOHHSw10UCr1t3mdWTc2k5x3msKpJwCLcB/s320/DSCF1185.jpg" width="320" /></a></div>
<br />
This is a textbook use case for an angle bearing, which looks like this:<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://1.bp.blogspot.com/-AyaQyyc0CQg/WIw79i6cZ2I/AAAAAAAA56I/cIMsNcRU30sR7BM4a0Qa4bwyNESvL92fgCEw/s1600/DSCF1182.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="215" src="https://1.bp.blogspot.com/-AyaQyyc0CQg/WIw79i6cZ2I/AAAAAAAA56I/cIMsNcRU30sR7BM4a0Qa4bwyNESvL92fgCEw/s320/DSCF1182.jpg" width="320" /></a></div>
<br />
See? That is meant to be loaded in BOTH directions and still remain stable and solid. At this point I couldn't help but notice the example bearing that I literally grabbed from a box in the lab happened to look like it might just fit...<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://1.bp.blogspot.com/-Dv6fiMBwyR8/WIw8ASvHE2I/AAAAAAAA56I/HYEcvsJACacq4lIhiV3P41tvnRNfH7tLACEw/s1600/DSCF1190.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="279" src="https://1.bp.blogspot.com/-Dv6fiMBwyR8/WIw8ASvHE2I/AAAAAAAA56I/HYEcvsJACacq4lIhiV3P41tvnRNfH7tLACEw/s320/DSCF1190.jpg" width="320" /></a></div>
<br />
Ok, crazy lucky: the center part was a matched fit for the rotating portion, and the outer ring was just a little bit small. You can see above that turned a little spacer on the lathe (which was a pain, it's way too thin to reasonably be clamped in the lathe, but I made it work). Ultimately I was able to get a pressed fit on both mating surfaces of the spacer:<br />
<div class="separator" style="clear: both; text-align: center;">
</div>
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-pBa6-M3JAho/WIw8A4y2yyI/AAAAAAAA558/gLlXT_zbHr8Edw7QCOX1B1XaVEdvtxhpACLcB/s1600/DSCF1194.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="254" src="https://1.bp.blogspot.com/-pBa6-M3JAho/WIw8A4y2yyI/AAAAAAAA558/gLlXT_zbHr8Edw7QCOX1B1XaVEdvtxhpACLcB/s320/DSCF1194.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">by pressed fit, I mean it needed some light bumps from a hammer</td></tr>
</tbody></table>
<div>
<br /></div>
</div>
<div>
If you'd like to duplicate what I did here, the bearing is an L68110. Unfortunately I can't recommend a source, because mine was "that box with random things like bearings in it." But they seem to be a pretty common bearing and go for $5-15 on the internet. </div>
<div>
<br /></div>
<div>
Other than that, I wiped down every greased up surface with a paper towel so that there was only a thin layer on everything. Once reassembled the mount would move much more freely, and I was able to do a much better job of tensioning each axis to prevent any free play in the system.</div>
<div>
<br /></div>
<div>
I still balance in DEC by setting the telescope assembly (with camera, all bolted to its dovetail) on a round object and teetering it until I find the balance point. I just mark that and slide it back on to the mount, centering the balance point in the dovetail clamp.</div>
<div>
<br /></div>
<div>
But RA couldn't be done like that, and now the RA axis moves very freely. I even went back later and re-tensioned after everything had settled, and was able to get a very tight, but free-spinning axis.</div>
<div>
<br /></div>
<div>
How much difference has this made? I don't have numbers yet as I'm still finding the right PHD settings, but so far things are more stable, it's easier to balance, and there's less play despite everything being much more aggressively tightened.</div>
<div>
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://2.bp.blogspot.com/-Qp_igCSOsPE/WIw7_X99mRI/AAAAAAAA56I/Wu92MiPXUXILA4eRDtipCxz9JXhp9tzYACEw/s1600/DSCF1175-Pano.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="212" src="https://2.bp.blogspot.com/-Qp_igCSOsPE/WIw7_X99mRI/AAAAAAAA56I/Wu92MiPXUXILA4eRDtipCxz9JXhp9tzYACEw/s640/DSCF1175-Pano.jpg" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">If you're like me, you really enjoy seeing all the bits of something that was taken apart. Enjoy!</td></tr>
</tbody></table>
<div>
Will this void your warranty? I would assume so. Could you un-do it? Probably. So save the original bearing and nylon washer, just in case...</div>
Spivhttp://www.blogger.com/profile/10510295596753094109noreply@blogger.com27tag:blogger.com,1999:blog-4756137234324004076.post-26338130802973692382017-01-22T22:13:00.001-05:002017-01-22T22:15:12.899-05:00Astrophotography: High ISO with short exposures or low ISO with long exposures?It is a very, very rainy night here and I've had a question nagging at my for a while. There are lots of suggestions on the internet for what sorts of settings to use while taking astro-photos. Lots of statements. Lots of advice. Very, very little data*. So here's the question I've seen asked and answered, but never proven. Boiled down to the point:<br />
<blockquote class="tr_bq">
<br />
<b>For every hour's worth of imaging time, is it better to take long exposures at a low ISO or shorter exposures at a high ISO?</b></blockquote>
<b><br /></b>
And I ask this, wanting to find a real reason, because I keep seeing complete nonsense regarding how cameras and ISO work. So here's what I did:<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://2.bp.blogspot.com/-gTpeWQP_PAY/WIVvtdh5jhI/AAAAAAAA5Zo/CIbcTc-sBgAOVE1-X1G4-Iv72BsEyQ0MwCLcB/s1600/IMG_20170122_173005%257E01.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="https://2.bp.blogspot.com/-gTpeWQP_PAY/WIVvtdh5jhI/AAAAAAAA5Zo/CIbcTc-sBgAOVE1-X1G4-Iv72BsEyQ0MwCLcB/s320/IMG_20170122_173005%257E01.jpg" width="205" /></a></div>
<br />
<br />
<ol>
<li>Set up the camera in a dark closet, with only the glow of a single amber LED, pointing at SpaceDuck.</li>
<li>Take a crap-ton of pictures. ~30 minutes of ISO 6400, 10 second exposures and ~30 minutes of ISO 400, 160 second exposures. Those should be similar exposures, but of course it won't exactly be.</li>
<li>Take 5 minutes of dark frames (same duration and ISO as their set) and 10 bias frames (/32,000ths of a second, but matching ISO of their set).</li>
<li>Process them just like I would any astrophoto using DeepSkyStacker</li>
<li>Present Results.</li>
</ol>
<div>
I legitimately went in to this having no idea what I'd get on the other end. I knew some of the information being shared was definitely wrong, but that there were almost certainly factors that I hadn't considered. I also legitimately don't know which way I'd like to see it go. I've worked pretty hard to make my Celestron AVX reliably track for 15+ minute exposures, but of course I don't think anyone really enjoys losing a frame that long because of a glitch/cloud/airplane/etc. </div>
<div>
<br /></div>
<div>
Unfortunately I failed to match the two exactly, but here's the stats (they're close, slightly in the favor of the longer exposures, but probably not enough to matter):</div>
<div>
<br /></div>
<br />
<table border="1" cellpadding="0" cellspacing="0" dir="ltr" style="border-collapse: collapse; border: 1px solid rgb(204, 204, 204); font-family: arial, sans, sans-serif; font-size: 13px; table-layout: fixed; text-align: center;"><colgroup><col width="169"></col><col width="100"></col><col width="100"></col></colgroup><tbody>
<tr style="height: 21px;"><td style="padding: 2px 3px 2px 3px; vertical-align: bottom;"></td><td data-sheets-value="{"1":2,"2":"High/Short"}" style="padding: 2px 3px 2px 3px; text-align: right; vertical-align: bottom;"><b>High/Short</b></td><td data-sheets-value="{"1":2,"2":"Low/Long"}" style="padding: 2px 3px 2px 3px; text-align: right; vertical-align: bottom;"><b>Low/Long</b></td></tr>
<tr style="height: 21px;"><td data-sheets-value="{"1":2,"2":"ISO"}" style="padding: 2px 3px 2px 3px; text-align: right; vertical-align: bottom;">ISO</td><td data-sheets-value="{"1":3,"3":6400}" style="padding: 2px 3px 2px 3px; text-align: right; vertical-align: bottom;">6400</td><td data-sheets-value="{"1":3,"3":400}" style="padding: 2px 3px 2px 3px; text-align: right; vertical-align: bottom;">400</td></tr>
<tr style="height: 21px;"><td data-sheets-value="{"1":2,"2":"Shutter Time(seconds)"}" style="padding: 2px 3px 2px 3px; text-align: right; vertical-align: bottom;">Shutter Time(seconds)</td><td data-sheets-value="{"1":3,"3":10}" style="padding: 2px 3px 2px 3px; text-align: right; vertical-align: bottom;">10</td><td data-sheets-value="{"1":3,"3":160}" style="padding: 2px 3px 2px 3px; text-align: right; vertical-align: bottom;">160</td></tr>
<tr style="height: 21px;"><td data-sheets-value="{"1":2,"2":"F/Stop:"}" style="padding: 2px 3px 2px 3px; text-align: right; vertical-align: bottom;">F/Stop:</td><td data-sheets-value="{"1":3,"3":2.8}" style="padding: 2px 3px 2px 3px; text-align: right; vertical-align: bottom;">2.8</td><td data-sheets-value="{"1":3,"3":2.8}" style="padding: 2px 3px 2px 3px; text-align: right; vertical-align: bottom;">2.8</td></tr>
<tr style="height: 21px;"><td data-sheets-value="{"1":2,"2":"Light Frames"}" style="padding: 2px 3px 2px 3px; text-align: right; vertical-align: bottom;">Light Frames</td><td data-sheets-value="{"1":3,"3":180}" style="padding: 2px 3px 2px 3px; text-align: right; vertical-align: bottom;">180</td><td data-sheets-value="{"1":3,"3":12}" style="padding: 2px 3px 2px 3px; text-align: right; vertical-align: bottom;">12</td></tr>
<tr style="height: 21px;"><td data-sheets-value="{"1":2,"2":"Light Frame Time"}" style="padding: 2px 3px 2px 3px; text-align: right; vertical-align: bottom;">Light Frame Time</td><td data-sheets-formula="=10*180" data-sheets-value="{"1":3,"3":1800}" style="padding: 2px 3px 2px 3px; text-align: right; vertical-align: bottom;">1800</td><td data-sheets-formula="=12*160" data-sheets-value="{"1":3,"3":1920}" style="padding: 2px 3px 2px 3px; text-align: right; vertical-align: bottom;">1920</td></tr>
<tr style="height: 21px;"><td data-sheets-value="{"1":2,"2":"Dark Frames"}" style="padding: 2px 3px 2px 3px; text-align: right; vertical-align: bottom;">Dark Frames</td><td data-sheets-value="{"1":3,"3":30}" style="padding: 2px 3px 2px 3px; text-align: right; vertical-align: bottom;">30</td><td data-sheets-value="{"1":3,"3":3}" style="padding: 2px 3px 2px 3px; text-align: right; vertical-align: bottom;">3</td></tr>
<tr style="height: 21px;"><td data-sheets-value="{"1":2,"2":"Dark Frame Time"}" style="padding: 2px 3px 2px 3px; text-align: right; vertical-align: bottom;">Dark Frame Time</td><td data-sheets-formula="=30*10" data-sheets-value="{"1":3,"3":300}" style="padding: 2px 3px 2px 3px; text-align: right; vertical-align: bottom;">300</td><td data-sheets-formula="=3*160" data-sheets-value="{"1":3,"3":480}" style="padding: 2px 3px 2px 3px; text-align: right; vertical-align: bottom;">480</td></tr>
<tr style="height: 21px;"><td data-sheets-value="{"1":2,"2":"Bias Frames"}" style="padding: 2px 3px 2px 3px; text-align: right; vertical-align: bottom;">Bias Frames</td><td data-sheets-value="{"1":3,"3":10}" style="padding: 2px 3px 2px 3px; text-align: right; vertical-align: bottom;">10</td><td data-sheets-value="{"1":3,"3":10}" style="padding: 2px 3px 2px 3px; text-align: right; vertical-align: bottom;">10</td></tr>
</tbody></table>
<div>
<style type="text/css"><!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}</style></div>
--><br />
<div style="text-align: center;">
<br /></div>
<div style="text-align: left;">
I basically have an extra dark in there for the Low/Long set because 2 frames just seemed unfair as far as averaging goes.</div>
<div style="text-align: left;">
<b><br /></b></div>
<div style="text-align: left;">
<b>These are all crops of the images because the originals are huge. But I'll share any originals if you want:</b></div>
<div style="text-align: left;">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://3.bp.blogspot.com/-MBDfxD2j0MM/WIVnEjCzRLI/AAAAAAAA5ZM/-Zlt9RbyysY1W60nIkI5IsujATYMhWiHQCEw/s1600/64-10-native.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto; text-align: left;"><img border="0" src="https://3.bp.blogspot.com/-MBDfxD2j0MM/WIVnEjCzRLI/AAAAAAAA5ZM/-Zlt9RbyysY1W60nIkI5IsujATYMhWiHQCEw/s1600/64-10-native.jpg" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Single Frame, 10 seconds @ ISO 6400</td></tr>
</tbody></table>
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://2.bp.blogspot.com/-C4c5D3ucDRQ/WIVnECXS7PI/AAAAAAAA5Yw/e6XkvwShpPQ_8NQDaHTdJ2H5i0TDpmA4ACEw/s1600/4-160-native.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://2.bp.blogspot.com/-C4c5D3ucDRQ/WIVnECXS7PI/AAAAAAAA5Yw/e6XkvwShpPQ_8NQDaHTdJ2H5i0TDpmA4ACEw/s1600/4-160-native.jpg" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Single Frame, 160 seconds at ISO 400</td></tr>
</tbody></table>
<div style="text-align: left;">
That's pretty predictable. And I chose this little section because it has a range of lightness from dark blue to white in the flag, plus shows a little ducky texture. Ever wonder why you have to take your dark frames at the same ISO and exposure length? Here's a couple singles, stretched using "auto tone" in Lightroom:</div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://4.bp.blogspot.com/-AeGf2QysKf4/WIVnEQCrJCI/AAAAAAAA5Y4/2OW3SBOy9AwCx9qE3rTRw7nYA3ybkNS6gCEw/s1600/64-10-dark.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="320" src="https://4.bp.blogspot.com/-AeGf2QysKf4/WIVnEQCrJCI/AAAAAAAA5Y4/2OW3SBOy9AwCx9qE3rTRw7nYA3ybkNS6gCEw/s320/64-10-dark.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Dark, 10 seconds @ 6400 stretched</td></tr>
</tbody></table>
<div style="text-align: left;">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://4.bp.blogspot.com/-pojjn1t0DwA/WIVnDxAuH2I/AAAAAAAA5Yg/2g-HoQzzcB0G12o8YeXlRQ3NmEQOte1hQCEw/s1600/4-160-dark.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="320" src="https://4.bp.blogspot.com/-pojjn1t0DwA/WIVnDxAuH2I/AAAAAAAA5Yg/2g-HoQzzcB0G12o8YeXlRQ3NmEQOte1hQCEw/s320/4-160-dark.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Dark, 160 seconds @ 400 stretched</td></tr>
</tbody></table>
and...<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://2.bp.blogspot.com/-CPb5MvXPzsY/WIVnEfG6NuI/AAAAAAAA5ZA/NOHeH-RXE_MssCbMONLimThd6izt0KDoQCEw/s1600/64-10-bias.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="320" src="https://2.bp.blogspot.com/-CPb5MvXPzsY/WIVnEfG6NuI/AAAAAAAA5ZA/NOHeH-RXE_MssCbMONLimThd6izt0KDoQCEw/s320/64-10-bias.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">1/32000th @ 6400 stretched</td></tr>
</tbody></table>
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-avrje4EmS5k/WIVnD1jKZYI/AAAAAAAA5Yc/CveEAS5-wqsrMGqNbs3x9MaDGgp091vFACEw/s1600/4-160-bias.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="320" src="https://1.bp.blogspot.com/-avrje4EmS5k/WIVnD1jKZYI/AAAAAAAA5Yc/CveEAS5-wqsrMGqNbs3x9MaDGgp091vFACEw/s320/4-160-bias.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">1/32000th @ 400 stretched</td></tr>
</tbody></table>
<br />
Be careful recycling dark and bias frames!<br />
<br />
So the next thing is that when you stack a lot of information together even tiny differences will multiply. This is my excuse for the next set of images not looking even as far as exposure is concerned, but ignore that and pay attention to how much information and detail is in them. First, the final results:<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://2.bp.blogspot.com/-G1aJa528Fwc/WIVnEr19ryI/AAAAAAAA5ZI/kCEdL2_GxGo8g-dq7cReo9_Boq9g5YBVACEw/s1600/64-10-final.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="320" src="https://2.bp.blogspot.com/-G1aJa528Fwc/WIVnEr19ryI/AAAAAAAA5ZI/kCEdL2_GxGo8g-dq7cReo9_Boq9g5YBVACEw/s320/64-10-final.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">180 frames stacked together from 10 seconds each <span style="font-size: 12.8px;">@ ISO 6400</span></td></tr>
</tbody></table>
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://3.bp.blogspot.com/-o-1baJYJZgE/WIVnEG4be2I/AAAAAAAA5Ys/ancIEUX9zKUgsEoz4NJUFDzWQz3vYBzLwCEw/s1600/4-160-final.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="320" src="https://3.bp.blogspot.com/-o-1baJYJZgE/WIVnEG4be2I/AAAAAAAA5Ys/ancIEUX9zKUgsEoz4NJUFDzWQz3vYBzLwCEw/s320/4-160-final.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">12 frames stacked together from 160 seconds each @ ISO 400</td></tr>
</tbody></table>
and then with the gamma adjusted to 1.45 for the ISO 6400 final to get closer to the look of the ISO 400:<br />
<div class="separator" style="clear: both; text-align: center;">
</div>
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://4.bp.blogspot.com/-cs1yAzjxXSI/WIVr-v4kbLI/AAAAAAAA5Zc/3m54hxFVkpQIP846NaM7Af8P7OQXNsLVgCLcB/s1600/64-10-final-gamma16.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="320" src="https://4.bp.blogspot.com/-cs1yAzjxXSI/WIVr-v4kbLI/AAAAAAAA5Zc/3m54hxFVkpQIP846NaM7Af8P7OQXNsLVgCLcB/s320/64-10-final-gamma16.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">180 frames stacked together from 10 seconds each <span style="font-size: 12.8px;">@ ISO 6400, 1.45 gamma correction</span></td></tr>
</tbody></table>
<br />
<div style="text-align: left;">
The plot thickens. If you ask me, those two are not all that far apart. Maybe there's a hint more ducky texture in the ISO 400 stack? Maybe that's just how the luminosity stretched? Let's step up the exposures on them in a couple increments to see what data is hiding, in case you were trying to pull faint nebulosity out of SpaceDuck. Note that these are stretched without the gamma, so the ISO 400 is going to appear a little lighter. Focus on the details:</div>
<div style="text-align: left;">
<br /></div>
<div style="text-align: center;">
<b>+2 stops</b></div>
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://2.bp.blogspot.com/-aiqeKQrIHJc/WIVnEg-Y3WI/AAAAAAAA5ZU/dZKURFtyZE0BT8JHAw4tT3hsvZ96f435wCEw/s1600/64-10-final-ex2.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="320" src="https://2.bp.blogspot.com/-aiqeKQrIHJc/WIVnEg-Y3WI/AAAAAAAA5ZU/dZKURFtyZE0BT8JHAw4tT3hsvZ96f435wCEw/s320/64-10-final-ex2.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">180 x 10s @ 6400 +2 stops exposure</td></tr>
</tbody></table>
<div style="text-align: left;">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://2.bp.blogspot.com/-4VDy9w6iKzc/WIVnDx5DtnI/AAAAAAAA5ZU/UamTNbYzibol1NSWImpuqg_5yLJHUpB0gCEw/s1600/4-160-final-ex2.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="320" src="https://2.bp.blogspot.com/-4VDy9w6iKzc/WIVnDx5DtnI/AAAAAAAA5ZU/UamTNbYzibol1NSWImpuqg_5yLJHUpB0gCEw/s320/4-160-final-ex2.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">12 x 160s <span style="font-size: 12.8px;">@ 400 </span><span style="font-size: 12.8px;">+2 stops exposure</span></td></tr>
</tbody></table>
<br />
<div style="text-align: center;">
<b>+ 5 stops</b></div>
<div style="text-align: center;">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://4.bp.blogspot.com/-RU-zqin-zZ0/WIVnEonCdaI/AAAAAAAA5ZU/rVBedLyOm8gT91nsyhxJhKeN_jk8ctXmACEw/s1600/64-10-final-ex5.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="320" src="https://4.bp.blogspot.com/-RU-zqin-zZ0/WIVnEonCdaI/AAAAAAAA5ZU/rVBedLyOm8gT91nsyhxJhKeN_jk8ctXmACEw/s320/64-10-final-ex5.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">180 x 10s <span style="font-size: 12.8px;">@ 6400 </span><span style="font-size: 12.8px;">+5 stops exposure</span></td></tr>
</tbody></table>
<div style="text-align: center;">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-whQorrJPt3w/WIVnD0VlauI/AAAAAAAA5ZU/iIfCEIscpaMJqi3m-clkScK_kCcEdgC4gCEw/s1600/4-160-final-ex5.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="320" src="https://1.bp.blogspot.com/-whQorrJPt3w/WIVnD0VlauI/AAAAAAAA5ZU/iIfCEIscpaMJqi3m-clkScK_kCcEdgC4gCEw/s320/4-160-final-ex5.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">12 x 160s <span style="font-size: 12.8px;">@ 400 </span><span style="font-size: 12.8px;">+5 stops exposure</span></td></tr>
</tbody></table>
<br />
<div style="text-align: center;">
<b>+ 10 stops</b></div>
<div style="text-align: center;">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-cb682-y172g/WIVnEf3ZR_I/AAAAAAAA5ZU/F-jsLTzHQdwE7a74UE8LTv_aX4HzJUefwCEw/s1600/64-10-final-ex10.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="320" src="https://1.bp.blogspot.com/-cb682-y172g/WIVnEf3ZR_I/AAAAAAAA5ZU/F-jsLTzHQdwE7a74UE8LTv_aX4HzJUefwCEw/s320/64-10-final-ex10.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">180 x 10s <span style="font-size: 12.8px;">@ 6400 </span><span style="font-size: 12.8px;">+10 stops exposure</span></td></tr>
</tbody></table>
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://4.bp.blogspot.com/-vR51aYQAOQU/WIVnD6-XYtI/AAAAAAAA5ZU/4HBs3LUsPQ8rKwj2PvrqE0UInzseAfxSwCEw/s1600/4-160-final-ex10.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="320" src="https://4.bp.blogspot.com/-vR51aYQAOQU/WIVnD6-XYtI/AAAAAAAA5ZU/4HBs3LUsPQ8rKwj2PvrqE0UInzseAfxSwCEw/s320/4-160-final-ex10.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">12 x 160s <span style="font-size: 12.8px;">@ 400 </span><span style="font-size: 12.8px;">+10 stops exposure</span></td></tr>
</tbody></table>
<div style="text-align: left;">
<br /></div>
<div style="text-align: left;">
So what do I think? I think the two are remarkably close, with a slight edge to the long exposures/low ISO. But it's much closer than I thought it would be. I think in the end I'll end up setting the camera to a high ISO, maybe even 6400, and taking more frames. Why? Because I think at the end of the night I'll end up with more total useful integration time. Too many things are out of my control when everything has to stay just right for 15 minute blocks.</div>
<div style="text-align: left;">
<br /></div>
<div style="text-align: left;">
<br /></div>
<div style="text-align: left;">
Other data/thoughts about the test in case you're wondering:</div>
<div style="text-align: left;">
<ul>
<li>The camera is a Fuji X-T1. I don't know if Nikons, Canons, Panasonics, etc work the same way as far as gain/ISO is concerned. Fuji is known for being wonderfully weird so do your homework. Repeat the test even and post it, because that's how science works :)</li>
<li>All files were taken as Fuji RAF raw files, which DSS doesn't like for me. So they are converted to DNG raw files. This probably doesn't make any difference, but it might especially given Fuji's also weird bayer filter pattern.</li>
<li>More dark frames is likely advisable for this amount of integration time.</li>
<li>I discovered Fuji reports exposure length incorrectly in the exif data. Things kept coming back saying they were 9 seconds and 170 seconds. I double checked manually with a stopwatch, those very much were 10 and 160 second exposures. Not sure what the story is.</li>
<li>Yes, 1/32,000th's of a second. The X-T1 can do a purely electronic shutter at ultra high speed. This is helpful in gathering read noise without other information.</li>
<li>When I auto-toned the two fullsize final images there is definitely a shade more detail in the absolute blackest of black background sections for the ISO 400 image. In a real image I think I would be powerless to discern that as signal from the noise, and would opt for a longer exposure in either case if that was detail I was actually trying to capture.</li>
</ul>
<div>
<span style="font-size: x-small;"><br /></span></div>
</div>
<div>
<i><span style="font-size: x-small;">*I'm not calling anyone out here. It happens. I can't even begin to explain how many times I've stopped after I said something in a barroom conversation and followed up with "now that I think about it I have no idea where I heard that or if it's true..."</span></i></div>
Spivhttp://www.blogger.com/profile/10510295596753094109noreply@blogger.com0tag:blogger.com,1999:blog-4756137234324004076.post-9111002499433003612017-01-13T20:29:00.000-05:002017-01-13T20:33:55.934-05:00Astrophotography resolution: what should "good" look like?One of the interesting challenges of astrophotography is that there are so very many factors that go in to the result. Basically, it can be difficult to determine what went wrong. Pull down your face shields, we're going to do something similar to science...<br />
<br />
I'm going to use my rig as an example, because, well, I did this math already. But that's ok because you can use use it to get some idea of things. I'll give you the math if you're really inspired to scribble on a big chalkboard and draw diagrams to impress your ladyfriend (or gentleman friend...and.... like other species geeks and nerds come in a variety of standards and even non-discrete units- gender/sexuality can't be determined by Millikan oil drop).<br />
<br />
The non-variables:<br />
<br />
<ul>
<li>I have a 6" f/4 telescope with optics of unknown quality</li>
<li>Through these optics, each pixel represents <a href="http://nova.astrometry.net/user_images/1446803#annotated" target="_blank">1.46 arc-seconds</a> of sky/star</li>
<li>My tracking scope (ST80) and its little camera reproduce <a href="http://nova.astrometry.net/user_images/1442267#annotated" target="_blank">1.93 arc-seconds per pixel</a></li>
<li>I have some messy data from my tracking scope in operation (used below)</li>
<li>The angular diameter of Sirius is 0.006 arc-seconds</li>
</ul>
<div>
I obtained the arc-seconds/pixel numbers for the two scopes by plate solving images taken from them using the wondrous tools at <a href="http://nova.astrometry.net/" target="_blank">nova.astrometry.net</a>.</div>
<div>
<br /></div>
<br />
So very simply, if the angular diameter of Sirius is less than one pixel of the sensor, and if everything was amazingly perfect it should look like this when magnified:<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://3.bp.blogspot.com/-NXvpH0ugNcE/WHgkTVJjOSI/AAAAAAAA3_s/BvCobt005GcW997sEezf0p38M3cuAtnCQCLcB/s1600/pixel1.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="318" src="https://3.bp.blogspot.com/-NXvpH0ugNcE/WHgkTVJjOSI/AAAAAAAA3_s/BvCobt005GcW997sEezf0p38M3cuAtnCQCLcB/s320/pixel1.png" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Not real life</td></tr>
</tbody></table>
<br />
<br />
If you claim to have seen such a thing you're a liar and a scoundrel.<br />
<br />
Any telescope's resolution is limited by the physics of light, simply because the quality of an optic, and how cleanly it reflects is proportional to the wavelength of light itself. Even if the optic is beyond the light's wavelength, the pinpoint of light will reproduce a central disk with rings of interference around it in a ratio of 84% in the middle, 16% in the rings. How long you expose the image will determine how bright the rings are, up to a point that they no longer appear as rings on the sensor and are instead a larger disk. This is why images of bright stars fill more pixels than dim ones. The size of this disk is determined by the diffraction limit, which is:<br />
<br />
<div style="text-align: center;">
1.22x wavelength(cm)</div>
<div style="text-align: center;">
----------------------</div>
<div style="text-align: center;">
diameter(cm)</div>
<div style="text-align: left;">
<br /></div>
<div style="text-align: left;">
in radians. So light somewhere in the middle of the spectrum: 0.00005cm and diameter of 15.2cm, we get 0.83 arc-seconds. Astro-Tech lists the scope's resolution as 0.76 arc-seconds. Isn't that interesting? At any rate, that's the area of the central disk. So in theory a short enough exposure would still render a single pixel. The diffraction rings, which look a bit like this:</div>
<div style="text-align: left;">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-1x1_aHBVa-A/WHgeBRXOyyI/AAAAAAAA3_c/PXBDDHEBAlI3Ey0nfMWXg74t8MqABlCegCLcB/s1600/disk.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://1.bp.blogspot.com/-1x1_aHBVa-A/WHgeBRXOyyI/AAAAAAAA3_c/PXBDDHEBAlI3Ey0nfMWXg74t8MqABlCegCLcB/s1600/disk.png" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Not to scale with the other fake pixels</td></tr>
</tbody></table>
<div style="text-align: left;">
<br /></div>
<div style="text-align: left;">
<br /></div>
<div style="text-align: left;">
would render as pixels something like this with sufficient exposure:</div>
<div style="text-align: left;">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://2.bp.blogspot.com/-Kefk_ntsjEE/WHgkYRiQM7I/AAAAAAAA3_w/JLA9i6jbihg3QctFozCi6EQ2ugaaGMNzgCLcB/s1600/pixel2.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="318" src="https://2.bp.blogspot.com/-Kefk_ntsjEE/WHgkYRiQM7I/AAAAAAAA3_w/JLA9i6jbihg3QctFozCi6EQ2ugaaGMNzgCLcB/s320/pixel2.png" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Real life if you're in space</td></tr>
</tbody></table>
<div style="text-align: left;">
<br />That's looking more like a star in a telescope like we're used to. This takes care of your Dawes numbers, Raleigh, or whatever else you subscribe to. Don't get too picky on the differences between those, we're taking pictures from the bottom of a deep pool.</div>
<div style="text-align: left;">
<br /></div>
<div style="text-align: left;">
Being in Florida I'm looking through about 30 feet of water in a best case scenario. It's a swampy, swampy state with a lot of dense, wet air starting at sea level. This produces "seeing" quality issues. The dense/wet air refracts light the same way that a glass (refactor) telescope does, except that it is constantly shifting with air currents, hundreds of times per second. If I were on Mauna Kea again that would distort the location of a given star (and its diffraction rings) by about 0.4 arc-seconds on a good night. Here? It's probably 2 arc-seconds on a good night, and likely 3 most of the time. Let's go with 2.5, or 1.7 pixels. Yes, I'm skipping over the concept of FWHM here because it's a calculus problem and you don't really need it for this sort of back-of-the-envelope look at things. Maybe another time. New image:</div>
<div style="text-align: left;">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://2.bp.blogspot.com/-CIuMT7HG0Io/WHgkczjPOVI/AAAAAAAA3_0/2CWu4O6kzvEd6hhzk86FvyWsnSG2amQpQCLcB/s1600/pixel3.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="318" src="https://2.bp.blogspot.com/-CIuMT7HG0Io/WHgkczjPOVI/AAAAAAAA3_0/2CWu4O6kzvEd6hhzk86FvyWsnSG2amQpQCLcB/s320/pixel3.png" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Scuba/Swamp Vision</td></tr>
</tbody></table>
<div style="text-align: left;">
<br /></div>
<div style="text-align: left;">
That's basically my expected detail if I get everything else completely right with a significant exposure. Shorter exposures of course could render a smaller image. In fact if the exposure was shorter than the frequency of eddie currents causing the seeing conditions (and I got lucky with a current that got very little distortion), and short enough to not expose the diffraction rings it could take up a single pixel. Instead, this is what I've got:</div>
<div style="text-align: left;">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-FzZ3L1PgbvQ/WHgnm81K0UI/AAAAAAAA4AA/TsM7QNNafhUfDJbQUL_Mvg62QlmuITR7wCLcB/s1600/pixel4.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="318" src="https://1.bp.blogspot.com/-FzZ3L1PgbvQ/WHgnm81K0UI/AAAAAAAA4AA/TsM7QNNafhUfDJbQUL_Mvg62QlmuITR7wCLcB/s320/pixel4.png" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">This should really only take up 4 or so pixels</td></tr>
</tbody></table>
<div style="text-align: left;">
<br /></div>
<div style="text-align: left;">
The shift of colors from red to blue tells me there's chromatic aberration, and because I can see it on other more significant things in that image comatic aberration as well. How do I know the stretch isn't tracking?</div>
<div style="text-align: left;">
<br /></div>
<div style="text-align: left;">
PHD2 unfortunately doesn't like my camera and won't let me put in a pixel size value for it, so it only reports deviation in pixels. Since I was able to plate solve an actual image from the camera though, it's easy math (arc-seconds = 1/(pixels per arc-second*deviation)):</div>
<div style="text-align: left;">
</div>
<ul>
<li>Average deviation of 0.45 pixels = .87 arc-seconds</li>
<li>peak deviation of 1.5 pixels = 2.95 arc-seconds</li>
</ul>
<div>
Those are for the ST-80, so arc-seconds being the common here that means going the other way for for the AT6IN/Fuji combo:</div>
<div>
<ul>
<li>average deviation of .87 arc-seconds = ~0.6 pixels</li>
<li>peak deviation of 2.95 arc-seconds = ~2 pixels.</li>
</ul>
<div>
The image is stretched over at least 3 pixels, so the only other candidate beyond my optical issues is focus. I'm focusing using a Bahtinov mask, which results in one of those scientifically accurate levels of focus that I can't determine by looking at pixels alone.</div>
</div>
<div>
<br /></div>
<div>
So...collimation, optics, aberration.</div>
<div>
<br /></div>
<div>
For reference, here's a bright star with a longer exposure. It's a little harder to tell what's going on there, but you get the idea:</div>
<div>
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-HCmsH-lMBPk/WHgtM8cR5jI/AAAAAAAA4AM/iir5meXmLlQyWVm9ZpV4jJ1d2gGHF0JTwCLcB/s1600/pixel5.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="318" src="https://1.bp.blogspot.com/-HCmsH-lMBPk/WHgtM8cR5jI/AAAAAAAA4AM/iir5meXmLlQyWVm9ZpV4jJ1d2gGHF0JTwCLcB/s320/pixel5.png" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Astro-probs.</td></tr>
</tbody></table>
<div>
<br /></div>
<br />
<div style="text-align: left;">
<br /></div>
<div style="text-align: left;">
<br /></div>
Spivhttp://www.blogger.com/profile/10510295596753094109noreply@blogger.com0tag:blogger.com,1999:blog-4756137234324004076.post-30470987307877528412017-01-12T17:52:00.002-05:002017-01-13T00:26:38.621-05:00Astrophotography updates, buying problems for myselfNew optics!<br />
<div>
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://3.bp.blogspot.com/-NU8h1dBUiow/WHf9L1fe_xI/AAAAAAAA3-4/nmEW-ZUizf0FsP0hlJ1kmBKbMfjD41agwCLcB/s1600/DSCF1001.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="424" src="https://3.bp.blogspot.com/-NU8h1dBUiow/WHf9L1fe_xI/AAAAAAAA3-4/nmEW-ZUizf0FsP0hlJ1kmBKbMfjD41agwCLcB/s640/DSCF1001.jpg" width="640" /></a></div>
<div>
<br /></div>
<div>
The main scope (for imaging) is an Astro-Tech AT6IN, and the new tracking scope is an Orion ShortTube-80, or ST80. There's a dozen versions of the ST80 of different names, all made by Synta for the various retailers.</div>
<div>
<br /></div>
<div>
I wanted something with a wider field of view, in this case the focal length is 610mm. Where the previous scope (a Celestron C6 SCT) rendered about 1.1 arc-seconds/pixel on my Fuji X-T1 camera, this renders closer to 1.5. In other words, it sees more sky.</div>
<div>
<br /></div>
<div>
This offers a few advantages:</div>
<div>
<ul>
<li>Tracking does not need to be as precise (we'll get to how much...)</li>
<li>I can image larger objects, such as the Pleiades, Rosette, and Horsehead/Flame nebula</li>
<li>Being the same aperture (6") but wider, that also means it's getting much more light every second the shutter is open.</li>
</ul>
How much more? If the previous scope was more or less F6.3, and this is F4, that's about 2.5x more light. So if I needed a 60 second exposure before, this would need a 24 second exposure. </div>
<div>
<b><br /></b></div>
<h3>
<b>And now I'm going to tell you why this was a terrible decision.</b></h3>
<div>
A short focal length Newtonian is a mess. It naturally has a ridiculous amount of comatic abberation, which is inherent in all large optics, but is exaggerated the shorter the focal length. Without a corrector this scope is basically worthless.</div>
<div>
<br /></div>
<div>
The coma corrector (made by GSO) mostly helps this...but your collimation (having all the optics at perfect angles to each other so that the light path is focused evenly/flatly on the image sensor) has to be really, really perfect. I've seen some estimates that at F/4 the image breakdown occurs when the light path deviates by as little as 0.45mm from accurate.</div>
<div>
<br /></div>
<div>
0.45mm. Let that sink in. You know how wide the bullseye is on a typical laser collimator? About 4mm. Part of that is because the output optic for a typical laser diode is 3mm.</div>
<div>
<br /></div>
<div>
So what you're doing is taking a really nice, wide angle image that should be able to get beautifully sharp and subjecting it to something that will begin breaking down at a level of accuracy that is 8-9x more accurate than the equipment you're going to calibrate it with.</div>
<div>
<br /></div>
<div>
Now suppose you're like me, and are the type that will stretch a thin film over your collimator so that you can see when the return light path, which is focused to much smaller than the exit light path, makes a nice bullseye in the exit path. Assuming you also loaded your collimator in a lathe at some point and centered that path to within a few mm at 50ft, you're probably able to get it within the margin of error.</div>
<div>
<br /></div>
<div>
If.</div>
<div>
<br /></div>
<div>
If the rest of your optics are aligned correctly, which... mine were not. Worse, they were not able to be: if you have a closer look at the image above you'll spot some extra holes where the secondary is mounted. My secondary mirror was too far down the tube to align correctly. Yay.</div>
<div>
<br /></div>
<div>
And then it still won't be good enough.</div>
<div>
<br /></div>
<div>
You'll hang a heavy imaging train off the side of the scope, which will cause the focuser to flex off of center on its mount. Your imaging train will have to be especially awkward because there's a heavy corrector optic in it, which then has a spacing of about 75-80mm (mine does best at 78mm) before it finds an imaging plane, which is probably a mirrorless camera or DSLR. This will shift things out of alignment by a couple mm. Which is enough to notice.<br />
<br /></div>
<h3>
<b>I think Newtonians might just be a bad idea anyway.</b></h3>
<div>
Once you've done all of this, you'll have a system which is very out of balance for the mount. The camera will sit at a different axis from the finder and tracking scopes (otherwise it will be in their way). You could add weights opposite of the focusing assembly, but of course this stresses the mount even more.<br />
<br /></div>
<h3>
<b>So...now what?</b></h3>
<div>
I don't know. I'm going to keep playing with it for the moment, and try not to get any farther down the rabbit hole unless I think I can make it truly work out. I have managed to take a couple ok-ish images with it, but far short of what I think my setup could otherwise do:</div>
<div>
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://2.bp.blogspot.com/-qF6QHskL15Q/WHgIT1HeBGI/AAAAAAAA3_I/afpn81m6fToh4PzdGWNNs6AkzSPE_7McACLcB/s1600/D-_dss_pl-2.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="410" src="https://2.bp.blogspot.com/-qF6QHskL15Q/WHgIT1HeBGI/AAAAAAAA3_I/afpn81m6fToh4PzdGWNNs6AkzSPE_7McACLcB/s640/D-_dss_pl-2.jpg" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Pleiades, stack of several 180s exposures from the Astro-Tech AT6IN and Fuji X-T1. Of course from my fully light polluted Central Florida skies.</td></tr>
</tbody></table>
<div>
<br /></div>
</div>
<div>
I like the wider field of view very much. Note: this was taken when I was still trying to get the coma corrector spaced out just right, so it shows worse on here than it is in some of my tests.</div>
Spivhttp://www.blogger.com/profile/10510295596753094109noreply@blogger.com2tag:blogger.com,1999:blog-4756137234324004076.post-84191799774181738112016-07-06T13:27:00.000-04:002016-07-06T13:27:57.255-04:00360 degree microphotography<div class="separator" style="clear: both; text-align: center;">
<iframe width="320" height="266" class="YOUTUBE-iframe-video" data-thumbnail-src="https://i.ytimg.com/vi/fmPc-NejJ44/0.jpg" src="https://www.youtube.com/embed/fmPc-NejJ44?feature=player_embedded" frameborder="0" allowfullscreen></iframe></div>
<br />
Summary: we took a microscope objective to my camera, built a focus stacking rig, and then combined it all with a miniature lazy susan / turntable to create a 360 degree rotation animation of a microscopic thing (in this case a common green long-legged fly, which has some pretty spectacular colors).<br />
<br />
Quick details:<br />
<br />
<ul>
<li>Each frame is a stack of 70 images</li>
<li>160 frames (about 2.25 degrees of rotation per frame)</li>
<li>Final is the product of 11,200 frames (though we took well over 20,000 while testing/developing)</li>
</ul>
<div>
Gear setup:</div>
<div>
<ul>
<li>Fuji X-T1</li>
<li>nameless eBay macro photography bellows</li>
<li>nameless eBay RMS adapter</li>
<li>AmScope PA4X microscope objective</li>
<li>Arduino Nano</li>
<li>Misc stepper motors and motor drivers</li>
<li>Custom motion control rig for focus stack and rotation</li>
</ul>
</div>
Spivhttp://www.blogger.com/profile/10510295596753094109noreply@blogger.com0tag:blogger.com,1999:blog-4756137234324004076.post-21198872461225574222015-11-14T12:49:00.000-05:002015-11-14T12:49:00.314-05:00Astrophotography: Solving Some Problems, Finding New Ones<div class="separator" style="clear: both; text-align: center;">
</div>
<div style="text-align: left;">
I made something I like!</div>
<div style="text-align: left;">
<br /></div>
<a href="http://3.bp.blogspot.com/-eD0jAzd5hsg/VkTCjv6uqiI/AAAAAAAAf8E/n-ompTNp9dA/s1600/DSCF5018-2.jpg" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" height="426" src="http://3.bp.blogspot.com/-eD0jAzd5hsg/VkTCjv6uqiI/AAAAAAAAf8E/n-ompTNp9dA/s640/DSCF5018-2.jpg" width="640" /></a><br />
<br />
<a href="http://3.bp.blogspot.com/-eD0jAzd5hsg/VkTCjv6uqiI/AAAAAAAAf8E/n-ompTNp9dA/s1600/DSCF5018-2.jpg" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><br /></a>
<br />
These are some of my changes:<br />
<br />
<ul>
<li>Better polar alignment; not seeing field rotation. This is my longest exposure too, at 480 seconds, which I would think would show that sort of thing if it were off by much at all.</li>
<li>Neodymium filter for light pollution, it blocked quite a bit!</li>
<li>More spacers between the reducer/corrector and the camera to reduce the vignette problems to a minimum.</li>
</ul>
<div>
You can see I haven't fixed the primary tube reflection yet, still waiting on materials to be delivered.</div>
<div>
<br /></div>
<div>
I plate solved the image using Astrometry and came up with a 1.1 arc-seconds per pixel. The theoretical limit of my 6" scope is around 0.9 arc-seconds. Seeing conditions were much worse than that, and for where I am will probably never be better than about 2 arc-seconds.So I think we are in a good place.</div>
<div>
<br /></div>
<div>
I also calculated out an effective focal length of 926mm f/6.2, not far from the advertised 945mm f/6,3 the reducer/corrector is supposed to get. I didn't try plate solving previous images, but I can tell you with some certainty that the Celestron recommendation of 105mm between the corrector and focal plane, as well as the internet's prediction of 85mm are wrong. Total distance from the back of the corrector to the surface of my sensor is 155mm. If you have a Celestron C6 and the standard f/6.3 reducer this is probably about where you want to be, at least if you are using an APS-C sensor sized camera.</div>
<div>
<br /></div>
<br />
<a href="http://4.bp.blogspot.com/-4wW6LFIms8E/VkTCjvNQGfI/AAAAAAAAf8A/tVaznHpO3rY/s1600/DSCF5015.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><br /></a>
<br />
<div style="margin-left: 1em; margin-right: 1em; text-align: center;">
</div>
<br />
For pure resolution, however, our tracking is not quite perfect. Here's a single color channel from the image above, cropped to the center of the nebula where the trapezium stars are very close together:<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="http://2.bp.blogspot.com/-al3bZuvboho/VkTCkCZv7hI/AAAAAAAAf8M/DdQ2D7So3ok/s1600/trapezium-long.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="291" src="http://2.bp.blogspot.com/-al3bZuvboho/VkTCkCZv7hI/AAAAAAAAf8M/DdQ2D7So3ok/s400/trapezium-long.png" width="400" /></a></div>
<br />
And the same spot, but with a quick 1 second exposure:<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="http://4.bp.blogspot.com/-4wW6LFIms8E/VkTCjvNQGfI/AAAAAAAAf8A/tVaznHpO3rY/s1600/DSCF5015.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="292" src="http://4.bp.blogspot.com/-4wW6LFIms8E/VkTCjvNQGfI/AAAAAAAAf8A/tVaznHpO3rY/s400/DSCF5015.jpg" width="400" /></a></div>
<br />
You can clearly see all four stars as separate in the 1 second shot. This means that either my guiding isn't reacting fast enough, isn't predictable enough, or doesn't have enough resolution to keep things perfectly centered. I suspect the latter is my issue. I will probably need to get a small scope with a longer focal length to keep up with the main telescope's resolution. Seeing conditions are at play here too, but unless I was particularly lucky with that 1 second picture they should be effecting that image similarly.<br />
<br />
For reference, the two stars closer together there are 8.7 arc-seconds apart:<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="http://2.bp.blogspot.com/-IlVI3fniD7s/VkTQJj5j6PI/AAAAAAAAf8o/Pbfrt1j_EP0/s1600/DSCF5015.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="203" src="http://2.bp.blogspot.com/-IlVI3fniD7s/VkTQJj5j6PI/AAAAAAAAf8o/Pbfrt1j_EP0/s320/DSCF5015.png" width="320" /></a></div>
<br />
Also, now that the field rotation is gone/minimized I can see we have some comatic aberration on stars at the outside edges of the frame:<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="http://1.bp.blogspot.com/-bS8b88yMsWQ/VkTCjvVnEhI/AAAAAAAAf8I/LPTj2MtwQCo/s1600/DSCF5016.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="370" src="http://1.bp.blogspot.com/-bS8b88yMsWQ/VkTCjvVnEhI/AAAAAAAAf8I/LPTj2MtwQCo/s400/DSCF5016.jpg" width="400" /></a></div>
<br />
Note that's coma, not chroma. This is the nature of the telescope. Stars in the center of the field focus to the same point from anywhere the light is gathered on the lens, but at the edges of the field those stars are focused at slightly different places depending on how close to the center of the lens the light was gathered. The reducer/corrector may be helping this or hurting it, depending on how much you believe I have moved the camera away from the "optimum" focal distance. There are additional correctors to help this, but this is so subtle I'm going to leave it alone for now.<br />
<br />
<br />Spivhttp://www.blogger.com/profile/10510295596753094109noreply@blogger.com1tag:blogger.com,1999:blog-4756137234324004076.post-13842909068777942502015-11-13T12:31:00.000-05:002015-11-14T11:34:50.921-05:00Cheap light pollution filter<div class="separator" style="clear: both; text-align: left;">
As soon as you say "filter" the public perception is that the images are photoshopped, or a little bit fake. I'm not one for heavily processing my images for other kinds of photography, and I'm more interested in being able to show what's up there in the night sky on the familiar terms that the general public is familiar with. There will always be limitations to this: "Is this what I would see?" doesn't exactly work in the world of nighttime photography in general.</div>
<div class="separator" style="clear: both; text-align: left;">
</div>
<ul>
<li>Your eyes are more sensitive, but they can't accumulate light over time like a camera. So things can be much brighter in pictures.</li>
<li>Your eyes see vivid color in the day time, but the darker it gets the more your eyes rely on the "rods" of your retina, which are monochromatic; things appear a bit more blue than grey, but sensing reds, greens, and vivid blues is out.</li>
<li>You're looking through a telescope, which is a form of filtering on its own. Your viewing angle is cut down from maybe 170 degrees to 1-2 degrees. Your effective pupil size is also expanded from a few millimeters to the diameter of the telescope to gather more light.</li>
</ul>
<div>
But none of those things speak to real filters, which is what I'm adding to the system but going to try to keep the color "real" as much as possible, at least for now.</div>
<div>
<br /></div>
<div>
Astronomy filters can be very specific, and the cost of even the simpler ones is very high. I'm only a few miles outside of the city and live where the air is quite thick, which means street lamps add an orange glow to the sky and really get in the way of seeing what's up there. The goal is to take pictures of things outside of our atmosphere, not the atmosphere itself, right?</div>
<div>
<br /></div>
<div>
The orange comes from sodium, and the good news is that there is a cheap solution to this. "Red enhancing" or Didymium filters are made with neodymium. This happens to block that range of light without blocking much else. Amazon had the 52mm version for $23, which happens to be exactly what I need. I just had to remove it from the threaded lens mount so I could put it in to the telescope:</div>
<br />
<div class="separator" style="clear: both; text-align: center;">
<br /></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="http://2.bp.blogspot.com/-SbhhfogyZXk/VkS7Uw3_1dI/AAAAAAAAf7o/ZRzuMujoBTY/s1600/DSCF4998.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="213" src="http://2.bp.blogspot.com/-SbhhfogyZXk/VkS7Uw3_1dI/AAAAAAAAf7o/ZRzuMujoBTY/s320/DSCF4998.jpg" width="320" /></a></div>
<br />
You can see by looking at the white cloth under the filter that it doesn't change the color very much.<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="http://2.bp.blogspot.com/-_GJAve5Ir8c/VkS7U5d9CnI/AAAAAAAAf7s/L8NuGPOZlLA/s1600/DSCF5001.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="313" src="http://2.bp.blogspot.com/-_GJAve5Ir8c/VkS7U5d9CnI/AAAAAAAAf7s/L8NuGPOZlLA/s320/DSCF5001.jpg" width="320" /></a></div>
<div class="separator" style="clear: both; text-align: center;">
<br /></div>
<div class="separator" style="clear: both; text-align: left;">
I wedged it in to the T2-FX adapter and used some cardboard as a spacer. I will replace the cardboard with something better and less reflective soon, but this was more than enough to test with.</div>
Spivhttp://www.blogger.com/profile/10510295596753094109noreply@blogger.com0tag:blogger.com,1999:blog-4756137234324004076.post-25308049699785815072015-11-12T07:00:00.000-05:002015-11-14T11:35:01.202-05:00Image artifacts: Astrophotography is touchyOnce I tied the camera to the back of my telescope and set up guiding I found plenty of new problems to solve:<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="http://2.bp.blogspot.com/-NSRmK6lL3DI/VkPID1P0Z2I/AAAAAAAAf2s/PrEuAgfhkLg/s1600/DSCF4980-3.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="426" src="http://2.bp.blogspot.com/-NSRmK6lL3DI/VkPID1P0Z2I/AAAAAAAAf2s/PrEuAgfhkLg/s640/DSCF4980-3.jpg" width="640" /></a></div>
<br />
I've boosted that image up a bit to make the flaws really obvious; this is a narrow view of the Pleiades. Surprisingly you can see some of the blue wisps of nebula around the stars (ignore the horseshoe shapes, those are artifacts)!<br />
<br />
My scope setup is:<br />
<ul>
<li>Celestron C6</li>
<li>Celestron f6.3 focal reducer/corrector</li>
<li>Standard Celestron SCT-T2 adapter</li>
<li>T2-FujiFX adapter</li>
<li>Fuji X-T1</li>
</ul>
<div>
Tracking is:</div>
<div>
<ul>
<li>Really cheap Orion 9x50mm</li>
<li>Even cheaper Microsoft LifeCam with the filters and lenses removed</li>
<li>PHD2 giuding software</li>
<li>GPUSB-ST4 box</li>
</ul>
<div>
Everything that's wrong:</div>
</div>
<div>
<ul>
<li>The orange-brown glow is my light polluted skies. We get nights that are clearer than that, but I think a filter would go a long way.</li>
<li>Stars in the center are nice and round, but the farther from center they are they are radially stretched. I believe this is a testament to how well autoguiding works. The system is locked on to the center star, but the alignment was off and so after a long exposure (300 seconds) the scope was not rotating exactly in tune with the skies. This makes the field seem to spin.</li>
<li>This thing that's going on:<br />
<a href="http://3.bp.blogspot.com/-HxOlZcHW3Jc/VkPKjBDAd1I/AAAAAAAAf24/aG53BrMkFVE/s1600/DSCF4980-3.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="213" src="http://3.bp.blogspot.com/-HxOlZcHW3Jc/VkPKjBDAd1I/AAAAAAAAf24/aG53BrMkFVE/s320/DSCF4980-3.png" width="320" /></a>
<br />is vignetting; light is being blocked by the sides of the scope's center passthrough tube. This might mean the camera is the improper distance away from the focal reducer (I don't have this without a focal reducer, but then my field of view is crazy narrow). The outlet of the scope is also narrow, which will force me to put the camera at a not-so-optimal focal point.</li>
<li>This one is light reflecting off of the inside of the telescope:<br />
<a href="http://1.bp.blogspot.com/-EEWInh__1mM/VkPMGXk32dI/AAAAAAAAf3E/3ErLnEFX20M/s1600/DSCF4980-3-1.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="213" src="http://1.bp.blogspot.com/-EEWInh__1mM/VkPMGXk32dI/AAAAAAAAf3E/3ErLnEFX20M/s320/DSCF4980-3-1.png" width="320" /></a>
<br />looks like a mix of the main body (very pale, I might not bother) and the primary mirror passthrough baffle. It's black but a bit glossy, and this is apparently a common complain for the C6. There's even a very light reflection inside the reflection going on for the brightest off-axis star, that's probably the T2 adapter tube.</li>
</ul>
<div>
The solutions are going to be a mix of things:</div>
</div>
<div>
<ul>
<li>Better polar alignment when imaging</li>
<li>Light pollution filter of some kind. I'm guessing 90% of sources are sodium based.</li>
<li>Move the camera back from the scope until I don't have vignetting; this turns out to be pretty far back. I've heard the "correct" number quoted at either 85mm or 105mm, the first place I found it vignette free was close to 140mm between the corrector and image sensor plane.</li>
<li>Black out the primary tube with protostar stick-on flocking. This might never go away completely, apparently SCT style scopes often have this issue. Sadly I don't have access to that crazy science grade paint that blocks 99.99xx% of light. If you do give me a holler.</li>
</ul>
<div>
Overall I think this is going pretty well, but I'm sure I'll find new problems once I fix some of these...</div>
</div>
<div class="separator" style="clear: both; text-align: center;">
<br /></div>
<div class="separator" style="clear: both; text-align: center;">
<br /></div>
<div>
<br /></div>
Spivhttp://www.blogger.com/profile/10510295596753094109noreply@blogger.com0tag:blogger.com,1999:blog-4756137234324004076.post-36781420924964599692015-11-11T16:54:00.000-05:002015-11-14T11:35:10.159-05:00"I accidentally a good equatorial mount."That's the gist of it anyway. I bought a Celestron AVX mount for peanuts because it said it was defective. I figured that the mechanics of it were well liked on the internet, but that some of the early versions had electrical problems. My goal was either to fix the control boards (if I could find something fixable) or to replace it all with my own control system.<br />
<br />
When it arrived on my doorstep I disassembled it completely and started looking over everything. Checked all the components that were check-able with a multi-meter and couldn't find a darn thing wrong. The control board was also the brand new version...something just didn't add up.<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="http://2.bp.blogspot.com/-80-3vxc3-BQ/VkO4r3ymYiI/AAAAAAAAf2c/mQxSQcEJOiQ/s1600/DSCF4817-2.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="212" src="http://2.bp.blogspot.com/-80-3vxc3-BQ/VkO4r3ymYiI/AAAAAAAAf2c/mQxSQcEJOiQ/s400/DSCF4817-2.jpg" width="400" /></a></div>
<br />
<br />
The mount came bare (no tripod, motor cables, power adapter, hand controller, weights, etc), so I had to get a few things before I could test it. Here are some mysteries I spent too much time researching, but solved:<br />
<br />
<ul>
<li>The 8 pin, RJ45 connector between the DEC motor and port is, in fact, just a standard straight-through cable like those used for networking. I made this to size using some CAT-5 and connectors I had.</li>
<li>The Nextstar+ hand controllers are all the same, the two model numbers for EQ and ALT-AZ are basically just there to let you know which firmware was loaded on the board. I know this because the budget friendly used one I acquired turned out to be loaded for ALT-AZ and gave me all sorts of trouble before I reloaded it (twice, the update software defaults to what it has regardless of which mounts it detects). Note the "+" though, the non-plus ones use different things inside and probably won't run the newer firmware.</li>
<li>You can use a regular 12v power adapter and ignore the fancy thread-on-overpriced one Celestron sells. I recommend tying it off though, the clipping part of it is rather weak and you don't want it to get pulled out of the connector if you can help it. I will probably replace this connector with either a standard one or a waterproof one in the future.</li>
</ul>
<div>
Once I plugged everything in the darn thing fired right up. I pointed it around during the day until I was satisfied there was nothing wrong with it, and then later on that night I tried to align it. That's when I discovered the ALT-AZ vs EQ firmware thing. Even though "EQ North" was a tracking option in the menu, it has no idea how to deal with the mount.</div>
<div>
<br /></div>
<div>
I managed to get a few images out of it with nothing more than a "that looks about right" aiming of the scope at Polaris and then manually pointing it at things, but nothing to write home about.</div>
<div>
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/-mK5n49Bp1_o/VkO3SzF8WZI/AAAAAAAAf2M/JR93Bh_FVuc/s1600/DSCF4964.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="425" src="http://3.bp.blogspot.com/-mK5n49Bp1_o/VkO3SzF8WZI/AAAAAAAAf2M/JR93Bh_FVuc/s640/DSCF4964.jpg" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Orion Nebula: Fuji X-T1. 30 second exposure, ISO 1000 @ 200mm F4.8</td></tr>
</tbody></table>
<div>
Things are forgiving at 200mm. It takes a lot more to get things right through a real telescope...</div>
Spivhttp://www.blogger.com/profile/10510295596753094109noreply@blogger.com0tag:blogger.com,1999:blog-4756137234324004076.post-17295697314899014292015-11-09T12:14:00.000-05:002015-11-09T12:14:15.946-05:00Minor Note...Having just tossed that last post on here as a convenient dumping ground, I couldn't help but skim my old content. I haven't added anything in a little over three years and I can't get my head around how much has changed.<br />
<br />
<ul>
<li>I'm still working on a lot of little projects, but in totally different ways.</li>
<li>I still love hiking and camping, but ghud ghawd I have learned a lot. These days I sleep outside just because I want a good night's sleep.</li>
<li>Which has helped me to travel this world a bit, nothing like the freedom of being able to get on a jet plane to anywhere with nothing but a backpack and a smile. I could, and probably should write books about how to do this.</li>
<li>I have definitely grown as a photographer. This has become a very important part of my life and I'm pleased to see this. I think drawing is a core of my approach, so I have worried that by not doing much drawing I wouldn't improve.</li>
<li>As far as I can tell I didn't write a thing in here about my physical activities, which are also central to my life at this point. I'm certain this started (restarted) in 2009, but apparently it was sometime after 2012 that it became apparent that this is essential to my self expression. Mind and body are not separate, at least for me.</li>
</ul>
<div>
I have no idea if anyone actually follows this blog after all this time, and I suppose don't care either way. Blogging for a day is good fun or narcissism, but blogging over years is something else entirely.</div>
Spivhttp://www.blogger.com/profile/10510295596753094109noreply@blogger.com0tag:blogger.com,1999:blog-4756137234324004076.post-19960033953901375432015-11-09T10:58:00.000-05:002015-11-14T11:35:25.136-05:00Data dump: Dew Heater EditionI have a number of projects going on right now, which I will hopefully have more to say about later on. Right now I think it's important that I get a few pieces of information and findings out there on the internet both for my own benefit and for other people who might be working in similar things.<br />
<br />
First: Here in the deep, deep, swampy south the dew point outside is typically one degree or less below air temperature. This means anything outside that has a view to the open sky will build up dew on it within a few minutes of exposure (the physics of radiative heat loss, maybe another post on another day). <br />
<br />
In my case I'm concerned about my telescopes, which means I want heating but not enough to cause visual distortion: air of two different temperatures creates a lensing effect at their boundary, think ripples of air over hot asphalt on a summer day. Remember this?<span style="background-color: black;"><span style="color: white;"><span style="font-family: inherit;"><br /></span>
</span></span><br />
<div class="separator" style="clear: both; text-align: center;">
<a href="http://2.bp.blogspot.com/-z6mKWZZhwu4/VkC9TvntBPI/AAAAAAAAfoE/PC1v_20IFPc/s1600/DSCN0229.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><span style="background-color: black; color: white;"><img border="0" height="240" src="http://2.bp.blogspot.com/-z6mKWZZhwu4/VkC9TvntBPI/AAAAAAAAfoE/PC1v_20IFPc/s320/DSCN0229.jpg" width="320" /></span></a></div>
<br />
That's colder/lighter gas distorting the air. Supposedly this happens significantly enough at 2 degrees F or less, but I don't have good data on that. Either way, the right answer is to keep a telescope as close to the air temperature around it as possible.<br />
<br />
The plan is to make a nice microcontroller circuit that measures the air temp and scope temp, and if the scope temp is low turn on a heater. This doesn't need to be terribly quick or smart or use PID since there's a lot of thermal mass involved, and I've designed the heaters to be very mild.<br />
<br />
I collected up most of the parts to do this, but a good test night rolled around first so I grabbed a cheap temperature controller I got from Ebay a while back just to get the heater kicking. Finding information on setting this up was difficult (it probably came with printed instructions, which don't last long in my possession). So here they are, if you have a cheap Chinese controller that looks like this:<span style="background-color: black;"><span style="color: white;"><span style="font-family: inherit;"><br /></span>
</span></span><br />
<div class="separator" style="clear: both; text-align: center;">
<a href="http://3.bp.blogspot.com/-1hyw1z6bIWg/VkC04ZFooiI/AAAAAAAAfnk/WbupBdkMFoE/s1600/DSCF4925.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><span style="background-color: black; color: white;"><img border="0" height="223" src="http://3.bp.blogspot.com/-1hyw1z6bIWg/VkC04ZFooiI/AAAAAAAAfnk/WbupBdkMFoE/s320/DSCF4925.jpg" width="320" /></span></a></div>
<div>
<br /></div>
Mine is labeled W2020 temperature controller, but let's assume it's China and there are 300 model numbers for the same product. Pressing "Set" once will let you use the arrow keys to change the desired temperature. Pressing and holding it for 5 seconds will enable a menu, which works like this:
<br />
<br />
<table border="1" cellpadding="0" cellspacing="1"><tbody>
<tr><td>Code</td><td>Code description</td><td>Setting range</td><td>Factory setting</td></tr>
<tr><td>P0</td><td>Cooling/Heating</td><td>C/H</td><td>C</td></tr>
<tr><td>P1</td><td>Hysteresis setting</td><td>0.1-30</td><td>2.0</td></tr>
<tr><td>P2</td><td>Highest setting upper limit</td><td>120</td><td>120</td></tr>
<tr><td>P3</td><td>Lowest setting upper limit</td><td>-55</td><td>-55</td></tr>
<tr><td>P4</td><td>Temperature correction</td><td>+10~-10C</td><td>0</td></tr>
<tr><td>P5</td><td>Delay start time</td><td>0-10minutes</td><td>0</td></tr>
<tr><td>P6</td><td>buzzer switch</td><td>on/off</td><td>off</td></tr>
<tr><td>P7</td><td>Value hold</td><td>on/off</td><td>off</td></tr>
<tr><td>P8</td><td>Restore factory settings</td><td>on/off</td><td>off</td></tr>
</tbody></table>
<br />
Change P0 to H since we're heating an object, and P1 (how far above/below desired temp it kicks on) to something nice and low since we want to keep it pretty close to our set temperature (in fact the temperature will likely spike above our set a little bit because the heater wire has some thermal mass).<br />
<br />
Oh, and the hookups on the back: NTC is the temperature probe, OUT is the heater (neither of these are polar since they are effectively resistors) and IN is power supply, with the little "o" denoting the positive side.<br />
<br />
<div style="text-align: center;">
<a href="http://1.bp.blogspot.com/-r4w5_FRW7uk/VkC1F5fLwmI/AAAAAAAAfn0/LqwIrB_Q8KQ/s1600/DSCF4926.jpg"><img border="0" src="http://1.bp.blogspot.com/-r4w5_FRW7uk/VkC1F5fLwmI/AAAAAAAAfn0/LqwIrB_Q8KQ/s320/DSCF4926.jpg" /></a></div>
<br />
There are commercially available telescope products to do all of this, but being the telescope world they are stupid expensive and probably don't have a lot of active development going on with them. Sorry astronomer friends, but that's the world I can see from here: once something "works" the discussion is done, even if it means using parts that haven't been produced in the last decade. Also for the disciples of Carl Sagan the physics of things is not often considered too deeply.<br />
<br />
My own complaining aside, the groundwork is solid. The internet tells me commercial heaters are about 0.75W/inch of circumference. This results in a heater that will just barely get warm to the touch, but seem like it isn't even working when stuck to a cold metal telescope. If you're lazy on math like I am and using a 12v power supply:<br />
<br />
<blockquote class="tr_bq">
amps * ohms = volts<br />
amps * volts = watts<br />
desired resistance (ohms) = 0.75watts / inches<br />
therefore:<br />
<b>desired resistence @ 12v = 192 ohms/inch of telescope circumference</b></blockquote>
<div>
Adjust if you're in a place that is freezing cold and humid, or if you're insulating the thing to start with, or not using 12v or whatever. I'm only here to solve my own problems.<br />
<br />
I grabbed some rolls of nichrome laying around the lab (doesn't everyone?) and came up with nice long wind of 18 gauge 80/20 wire. Pro tip: other websites will tell you to make a mess of parallel heaters or funky ways of staggering your wire to come up with enough length for a given resistance. Easier way: buy a few different thicknesses of wire, thicker stuff will end up with a longer length for the given resistance. If you have a small bodie'd thing like a spotting scope you probably want 26+ gauge, bigger scopes might be 16-20 gauge. Note that having too short of a run also means you will be putting all of that heat in to a smaller area, risking damage by making a miniature toaster coil for your precious equipment. Get the right wire for the job. It will make your life easier.<br />
<br />
I also didn't like the idea that the commercial heaters only heated the very front of the scope: the whole scope gets soaked here, which I don't want it dripping on to other electronics, rusting, mildewing, or just generally being gross to carry back in to the house. There's also some general nonsense about trying to radiate heat back across the glass from in front, which sounds nice except for the body of the scope (and therefore the back of the glass) having a big thermal gradient as a result. Keep the body of the scope, inside and out, at air temperature and things will be much happier:<br />
<br />
<div style="text-align: center;">
<a href="http://4.bp.blogspot.com/-oMWf8qQXDI4/VkC0-kOUeHI/AAAAAAAAfns/LbrQ8fKETrA/s1600/DSCF4923.jpg"><img border="0" src="http://4.bp.blogspot.com/-oMWf8qQXDI4/VkC0-kOUeHI/AAAAAAAAfns/LbrQ8fKETrA/s320/DSCF4923.jpg" /></a></div>
<br />
Kapton tape is cool stuff: extremely heat tolerant (we use this stuff on the heater part of our 3d printer, which spends hours at 260+C), durable and thin. Once I had figured out about how many winds of wire would go around the scope I marked out the appropriate distance between them and laid down a couple layers to electrically insulate the wire from the tube. I wrapped the coil and a top layer of kapton together leaving just a couple of ends exposed for connection. You can see that by having some 14 feet of wire to provide the appropriate wattage I had a lot more flexibility than "just the tip" heaters like astrozap, kendrick, dewbuster, etc. Plus my cost was $10 for the controller and 'it was collecting dust' for the wire, say $10-20 if you had to buy it (you will have a lot leftover if you do). A roll of kapton tape is only a few dollars, and you should have some just for the fun of it. They sent that stuff to the moon, you know.<br />
<br />
The test was pretty simple: I set the scope up outside and let it cool down until dew formed on the front glass (less than 10 minutes). This was a rare night in which outside was colder than inside (everyone else talks about letting the scope cool down after being inside...I get that for a couple months each year here). I turned on the heater and 5 minutes later the controller shut off: the glass was clear. Yeehaw. I left it outside for a few hours and the heater would click on and off every few minutes, scope never showed a hint of dew again.<br />
<br />
The upside is that it does the trick, the downside is that I have to manually set a temperature. Next step is making a real controller to automate an accurate temperature setting.<br />
<br />
<br />
<br />
<br />
<br /></div>
Spivhttp://www.blogger.com/profile/10510295596753094109noreply@blogger.com0tag:blogger.com,1999:blog-4756137234324004076.post-24923227897296985492012-08-06T18:26:00.001-04:002012-08-06T18:26:28.658-04:00Raspberry Pi, the Second Helping<br />
Have you ordered yourself one of these yet? No? Well what's wrong with you? They're fun. I'm going to proceed to be a really lousy inspiration for you to get one by telling you about some of the things I've done and had trouble with.<br />
<br />
First of all I decided to stick with Raspbian as the OS simply because it is pretty far along and has a lot of support right now. In the mean time Gentoo has starting making releases, and I expect they will be another very popular option.<br />
<br />
I dedided a good challenge would be to replace my Windows based server (previously mentioned Intel Atom in a spacious rack mount bay). The main features it would require are:<br />
<br />
<br />
<ol>
<li>Remote Music Player (accessible by phone/tablet)</li>
<li>Web Server (HTTP, PHP, PERL, MySQL)</li>
<li>FTP Server (FTP/SFTP)</li>
<li>Download Server (accessible by phone/tablet)</li>
</ol>
<br />
<br />
Looking down these they all are things to be accessed remotely, and I would have very little use for a desktop environment for them. Since a desktop takes a lot of overhead I decided I should stick to the command line. And I haven't booted the desktop environment since. Fun right? No, seriously. It's fun. You just forgot. Like I did. Because most of us only crack open a terminal window every now and then when someone hasn't made a button to do something for us. Or perhaps check our IP address or something.<br />
<br />
This also means at some point I unplugged the mouse and couldn't think of a reason to plug it back in. I replaced it with an external hard drive, which, BTW, needs to either have its own power source or be plugged in to a powered USB hub. The 'Pi doesn't have much juice on the ports.<br />
<br />
The web server and FTP seemed like a good place to start, so I pulled in the packages for this:<br />
<br />
<blockquote class="tr_bq">
<span style="font-family: Courier New, Courier, monospace;">sudo apt-get install apache2<br />sudo apt-get install php5<br />sudo apt-get install mysql-client mysql-server<br />sudo apt-get install postfix</span></blockquote>
<br />
And that was pretty much it. Apache is the http stuff, PHP is a useful programming language for web that things like wordpress run on, MySQL is database, and postfix is email (which is useful for having your pages send messages out). I made some minor adjustments to /etc/apache2/httpd.conf and /etc/apache2/ports.conf using a command line text editor, example:<br />
<br />
<blockquote class="tr_bq">
<span style="font-family: Courier New, Courier, monospace;">sudo pico /etc/apache2/httpd.conf</span></blockquote>
<br />
(You make your edits and then press ctrl + x and follow the prompts from there. There are other command line editors besides pico, so dig around and find one you like. Or don't. I mean it's editing things with a keyboard. There probably isn't a text editor that will make unicorns shoot out of your pupils.)<br />
<br />
Speaking of, this is where I noticed my first "oops." It turns out that the default keyboard setup is for Britain, and so my Amuricah the Keyboard had a few keys rearranged and inaccessible (*nix is hard to work with when you don't have a \, ~, or |, even if you can find they swapped # and @ to other places Plus it means you have to curse at the machine without censoring). Fix this by changing "gb" to "us" in /etc/default/keyboard. Unless you're British. In which case chortle at the yank' luddites.<br />
<br />
A quick check by going to the Pi's local IP address from another computer confirmed I had web service running.<br />
<br />
Next up was FTP:<br />
<br />
<blockquote class="tr_bq">
<span style="font-family: Courier New, Courier, monospace;">sudo apt-get install vsftpd</span></blockquote>
<br />
I had to edit this one a fair amount to get users added to the system. You can find a lot of info about this by reading about VSFTPD, it's not difficult but this post is going to be long enough already.<br />
<br />
At any rate I did manage to get it working, got permissions set on the folders that would be used, and made an alias to the web server's www directory using<br />
<br />
<blockquote class="tr_bq">
<span style="font-family: Courier New, Courier, monospace;">mount --bind [a] [b]</span></blockquote>
<br />
where [a] = what you want to link from and [b] is where you want to link to, in my case /srv/ftp/www and /var/www respectivly. This knowledge will come in handy later when you decide you want large folder of files to not reside on the SD card.<br />
<br />
More to come...<br />Spivhttp://www.blogger.com/profile/10510295596753094109noreply@blogger.com3tag:blogger.com,1999:blog-4756137234324004076.post-16589387398966776822012-07-30T14:07:00.002-04:002012-07-30T14:07:53.812-04:00Raspberry Pi<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/-z_xSlqQ35_M/UBbLHyMgdJI/AAAAAAAADJQ/9Xnye69tcYg/s1600/rpi.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="236" src="http://4.bp.blogspot.com/-z_xSlqQ35_M/UBbLHyMgdJI/AAAAAAAADJQ/9Xnye69tcYg/s320/rpi.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">There are many like it, but this one is mine.</td></tr>
</tbody></table>
<br />
You all know I'm a card carrying Arduino party member to the point that I buy parts in bulk to keep my per-arduino builds (for the controller part anyway) under about $7/each. That might make for another interesting topic. But the key is that they are very cheap ways to control something with a computer.<br />
<br />
You know my nerd hairs* stood up when I heard about the $25-35 Raspberry Pi; an ARMv6 based computer that runs a Debian Linux distribution. It took a while to aquire one here in the U.S., but mine finally arrived from Newark a few days ago.<br />
<br />
Selling points:<br />
<br />
<ul>
<li>Powers off of a phone charger</li>
<li>General purpose input/output pins</li>
<li>runs linux</li>
<li>HDMI video output, capable of some pretty high res stuff</li>
<li>boots from a cheap SD card</li>
<li>USB support</li>
<li>It's a whole computer for Thirty Five Dollars.</li>
<li>2.5Watts of power consumption (that I measured anyway)</li>
</ul>
<br />
Let me start by linking to a few important resources:<br />
<br />
<ul>
<li><a href="http://www.raspberrypi.org/faqs" target="_blank">Home page FAQ</a>, with a nice diagram showing important parts </li>
<li>Where I got mine on the not-too-long-of-wait; <a href="http://www.newark.com/raspberry-pi/raspbrry-pcba/raspberry-pi-model-b-board-only/dp/83T1943?in_merch=Popular%20Products&in_merch=Popular%20Products&MER=PPSO_N_C_EverywhereElse_None" target="_blank">Newark/Element14</a> </li>
<li>Various versions of <a href="http://elinux.org/RPi_Distributions" target="_blank">Linux available for your RPi</a></li>
<li>A <a href="http://elinux.org/RPi_VerifiedPeripherals" target="_blank">list of confirmed hardware</a> that works, like WiFi adapters, keyboards, mice, etc.</li>
</ul>
<br />
And on the note of the distributions: you load them to an SD card. Unfortunately the fancy 30Mbit Sandisk Extreme cards that I use for photography didn't work, but every other one I picked up around the house did. Get yourself a copy of <a href="http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CHUQFjAA&url=http%3A%2F%2Fwww.7-zip.org%2F&ei=WswWUNLXDor30gGLxoCoCQ&usg=AFQjCNElgl3u-wgL-ZOjo_CH4znsHpsyyw&sig2=Cwdf3EYJJBdJeYmKI-6-_A" target="_blank">7zip</a> and and <a href="http://launchpad.net/win32-image-writer" target="_blank">Win32DiskImager</a> if you are working out of a windows machine. 7zip takes care of the obscure compression formats that linux people are more familiar with (.gz, .xz, etc) and the disk imager builds an imaged SD card from a .img file. After you've cleared those little hurdles you should probably try downloading a few different distributions to play around with. It's easy and safe fun.<br />
<br />
I did have troubles with most of them (standard linux troubles, of which we have made many jokes at the expense of others who think "linux makes a fine desktop for regular people" can include "it's easy to install! Just go to the command line and do these 15 things, then edit this file, then recompile, then...."). I had such flawless experience when messing with wireless network drivers (of which I never resolved).<br />
<br />
It does however do a pretty good job of making me all nostalgic for the finer things of working with computers in the early and mid 90's. This is in many ways the goal of the thing. It's aimed at education of future software developers, of which I would certainly credit my having been toying around on the lovely machines of the pre Windows95 era.<br />
<br />
Now you're asking yourself: what exactly am I supposed to do with this thing? Well if you go with <a href="http://www.techrepublic.com/blog/european-technology/10-coolest-uses-for-the-raspberry-pi/505" target="_blank">TechRepublic</a> perhaps you should be building small satellites. But they do have some good suggestions for those not in possession of an orbital capable vehicle.<br />
<br />
Borrowing from their list, these are the things I can see me doing with it:<br />
<br />
<ul>
<li>Arcade Cabinet: We've chattered about this one many times at the house. Could be cheap fun.</li>
<li>Media Server: it does indeed play 1080p video, and there's a great distro (openELEC, available above) that is built just for that. It boots straight to XBMC and everything is handled from there.</li>
<li>Network attached things: Cameras, power monitoring, etc. Getting an Arduino on to a network is actually quite a pain. This is a good alternative.</li>
<li>Machine control: There are lots of linux based cnc programs out there, and the GPIO (general purpose input/output) on the Pi isn't much of a stretch to plug in to hardware. </li>
<li>Telescope auto-guiding: You can get various devices from Orion and others that cost a boatload. Why? Because they mount a camera on the back of a secondary telescope and do image processing to determine if a guiding star is wandering from the field of view. There is already a 5 megapixel camera accessory on its way. This could handle that and much more (such as identifying stars from a catalog). </li>
<li>Webserver: Whenever someone hears the word "server" they always seem to picture a ten foot tall rack mount tower with hundreds of cables dangling off like electric tentacles, possibly with CO2/Nitrogen vapor lightly rolling down the side. My home web server (which we use for all sorts of odd things) runs on an intel atom mini-ITX kind of thing. It's the least dense thing in my rack, and only a rack because it might as well sit in with the other audio toys. This may replace that with a simple Apache install. </li>
</ul>
<br />
Things that sound like a good idea but probably are not:<br />
<br />
<ul>
<li>CarPC: It sounds like a great idea, but once you factor in getting a screen you're probably paying more and getting less than wiring in an android tablet. I don't know if you've seen the quality of screens on these tablets, but they are far ahead of the liliput screens out there. It also turns out that a Kindle Fire is almost exactly a double-DIN size.</li>
<li>DIY Tablet: Good luck to ya. I do not know how they manage to build something like the Nexus 7 for as cheap as they do, so what you make is almost certainly going to be something of a novelty. That's cool and all, but of little interest to me.</li>
</ul>
<br />
So that's my opening. I'll keep us all updated as new cool things come to mind and we start building things with this new tool. Assuming I don't just regress to 1993 and start dialing in to some BBSs.<br />
<br />
*I think those are the ones on the back of your elbows<br />Spivhttp://www.blogger.com/profile/10510295596753094109noreply@blogger.com2tag:blogger.com,1999:blog-4756137234324004076.post-166225211169868692012-07-09T02:07:00.000-04:002012-07-09T02:07:00.772-04:00A Summer of Alligator Hatchlings, the first out<div class="separator" style="clear: both; text-align: left;">
These were the first of the season, nested deep in the Econlockhatchee Forest. Interesting fact: nest temperature determines gender. On a normal year hatchlings come 5:1 female, but this year is different. Because this nest was buried pretty far in to the woods instead out out in the swamp, and because it was early enough in the year, this might be one of the only female clutches for this part of Florida. The open swamps like Wetlands Park didn't hatch until much later.</div>
<div class="separator" style="clear: both; text-align: left;">
<br /></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="http://3.bp.blogspot.com/-ad_JBjL-ZPs/T_fRb8LFvaI/AAAAAAAADHQ/wWNT-QXupD8/s1600/DSC_0117.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="426" src="http://3.bp.blogspot.com/-ad_JBjL-ZPs/T_fRb8LFvaI/AAAAAAAADHQ/wWNT-QXupD8/s640/DSC_0117.jpg" width="640" /></a></div>
<div class="separator" style="clear: both; text-align: center;">
<br /></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="http://2.bp.blogspot.com/-dhjsmXfyYfQ/T_fRaum4CgI/AAAAAAAADHA/MC0xpZqIFH4/s1600/DSC_0015.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="422" src="http://2.bp.blogspot.com/-dhjsmXfyYfQ/T_fRaum4CgI/AAAAAAAADHA/MC0xpZqIFH4/s640/DSC_0015.jpg" width="640" /></a></div>
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="http://4.bp.blogspot.com/-f1aaKnjU1GE/T_fRbNEQPeI/AAAAAAAADHI/NpxV6DAG9IY/s1600/DSC_0031.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="424" src="http://4.bp.blogspot.com/-f1aaKnjU1GE/T_fRbNEQPeI/AAAAAAAADHI/NpxV6DAG9IY/s640/DSC_0031.jpg" width="640" /></a></div>
<br />
<br />Spivhttp://www.blogger.com/profile/10510295596753094109noreply@blogger.com0tag:blogger.com,1999:blog-4756137234324004076.post-47634980206925791792012-07-07T02:03:00.002-04:002012-07-07T02:03:35.101-04:00A Summer of Alligator Hatchlings<div class="separator" style="clear: both; text-align: left;">
This summer I've done a lot of hiking through the swampiest of swampy Florida during hatching season. I figure I'll share the cuter of the little guys with everyone starting with this lil' fella:</div>
<div class="separator" style="clear: both; text-align: left;">
<br /></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="http://2.bp.blogspot.com/-DGJOyvTx7Z8/T_fQroyyNHI/AAAAAAAADG4/Oq9Ol3z5jzQ/s1600/DSC_1143.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="424" src="http://2.bp.blogspot.com/-DGJOyvTx7Z8/T_fQroyyNHI/AAAAAAAADG4/Oq9Ol3z5jzQ/s640/DSC_1143.jpg" width="640" /></a></div>
<br />Spivhttp://www.blogger.com/profile/10510295596753094109noreply@blogger.com0tag:blogger.com,1999:blog-4756137234324004076.post-28781616460553594642012-06-06T08:00:00.001-04:002012-06-06T08:00:27.711-04:00Transit of venus<div><p>Well...I got to see it. Just in this one moment through the storm clouds.</p>
<br/><img src='http://lh5.ggpht.com/-2lyI6O3o2Qg/T89GP8K-S6I/AAAAAAAADGs/awEcSe6m5CQ/DSC_0751.png' /></div>Spivhttp://www.blogger.com/profile/10510295596753094109noreply@blogger.com0tag:blogger.com,1999:blog-4756137234324004076.post-31462779817447013912012-06-04T16:22:00.000-04:002012-06-04T16:22:00.115-04:00Useful links for later...<a href="http://www.glacialwanderer.com/hobbyrobotics/?p=16" target="_blank">Lightning detector built from an arduino platform</a>Spivhttp://www.blogger.com/profile/10510295596753094109noreply@blogger.com0tag:blogger.com,1999:blog-4756137234324004076.post-29068555546145610802012-05-15T16:28:00.001-04:002012-05-15T16:28:58.827-04:00Feeds and SpeedsJust another little tidbit, this time from the CNC project. Because I lost some sleep over this.<br />
<br />
So I'm milling a lot of aluminum and making a horrible mess. Kept adjusting the feed rates, spindle RPMs, and all that trying to get this silly thing to make some cuts and feeling like I was getting slower and slower and the results just weren't looking right. So finally I remembered that I don't really know much about machining and punted from the internet to see what kinds of settings other people were using.<br />
<br />
Long story short it seems hard to find just a simple table that would get a person, you know, like in the vague area of what they should be doing. But eventually I did find some equations.<br />
<br />
The results? I was off by about two orders of magnitude on my last attempt. And killing my bits prematurely. Here's the basic idea:<br />
<br />
<div style="text-align: center;">
<b>RPMs = feed rate / (number of flutes * chip size</b>)</div>
<br />
that's pretty rough and there are lots of variables to take in to consideration (coolant, how much block am I actually cutting, is it a pocket, bla bla bla) but this seems like a good starting place. Re-arrange that for whatever variable you have easy control over.<br />
<br />
The idea is simple actually: your chip size has to be bigger than the roundness of your bit (which really does always have a little bit of roundness and usually a chamfer leading to the cutting surface). Otherwise you are just scrubbing the outside of the bit against the aluminum until it wears down or melts/wears away. This is called burnishing. You might as well have loaded the machine up with a slightly roughened carbide rod instead of a proper endmill. A good size for this is 0.004 inches and up on a 1/4" bit. So I tossed together this little chart with the idea that I would be taking out 0.005 inch chips. ipm = inches per minute and all the numbers in white are RPMs for the spindle:<br />
<div style="text-align: center;">
<br /></div>
<br />
<center>
<table border="0" cellpadding="0" cellspacing="0" style="border-collapse: collapse; text-align: center; width: 231px;">
<colgroup><col style="mso-width-alt: 1426; mso-width-source: userset; width: 29pt;" width="39"></col>
<col span="3" style="width: 48pt;" width="64"></col>
</colgroup><tbody>
<tr height="20" style="background-color: #3d85c6; height: 15.0pt;">
<td height="20" style="height: 15pt; text-align: center; width: 29pt;" width="39"></td>
<td style="width: 48pt;" width="64"><div style="text-align: center;">
<b><u><br /></u></b></div>
</td>
<td style="text-align: center; width: 48pt;" width="64"><u><b>flutes</b></u></td>
<td style="text-align: center; width: 48pt;" width="64"></td>
</tr>
<tr height="20" style="background-color: #3d85c6; height: 15.0pt;">
<td height="20" style="height: 15.0pt;"><div style="text-align: center;">
<u><b>ipm</b></u></div>
</td>
<td class="xl63" style="text-align: right;"><div style="text-align: center;">
2</div>
</td>
<td class="xl63" style="text-align: right;"><div style="text-align: center;">
3</div>
</td>
<td class="xl63" style="text-align: right;"><div style="text-align: center;">
4</div>
</td>
</tr>
<tr height="20" style="height: 15.0pt;">
<td class="xl63" height="20" style="background-color: #3d85c6; height: 15pt; text-align: right;"><div style="text-align: center;">
0.25</div>
</td>
<td class="xl64" style="text-align: right;"><div style="text-align: center;">
25</div>
</td>
<td class="xl64" style="border-left-style: none; text-align: right;"><div style="text-align: center;">
17</div>
</td>
<td class="xl64" style="border-left-style: none; text-align: right;"><div style="text-align: center;">
12.5</div>
</td>
</tr>
<tr height="20" style="height: 15.0pt;">
<td class="xl63" height="20" style="background-color: #3d85c6; height: 15pt; text-align: right;"><div style="text-align: center;">
0.5</div>
</td>
<td class="xl64" style="border-top-style: none; text-align: right;"><div style="text-align: center;">
50</div>
</td>
<td class="xl64" style="border-left-style: none; border-top-style: none; text-align: right;"><div style="text-align: center;">
33</div>
</td>
<td class="xl64" style="border-left-style: none; border-top-style: none; text-align: right;"><div style="text-align: center;">
25</div>
</td>
</tr>
<tr height="20" style="height: 15.0pt;">
<td class="xl63" height="20" style="background-color: #3d85c6; height: 15pt; text-align: right;"><div style="text-align: center;">
1</div>
</td>
<td class="xl64" style="border-top-style: none; text-align: right;"><div style="text-align: center;">
100</div>
</td>
<td class="xl64" style="border-left-style: none; border-top-style: none; text-align: right;"><div style="text-align: center;">
67</div>
</td>
<td class="xl64" style="border-left-style: none; border-top-style: none; text-align: right;"><div style="text-align: center;">
50</div>
</td>
</tr>
<tr height="20" style="height: 15.0pt;">
<td class="xl63" height="20" style="background-color: #3d85c6; height: 15pt; text-align: right;"><div style="text-align: center;">
2</div>
</td>
<td class="xl64" style="border-top-style: none; text-align: right;"><div style="text-align: center;">
200</div>
</td>
<td class="xl64" style="border-left-style: none; border-top-style: none; text-align: right;"><div style="text-align: center;">
133</div>
</td>
<td class="xl64" style="border-left-style: none; border-top-style: none; text-align: right;"><div style="text-align: center;">
100</div>
</td>
</tr>
<tr height="20" style="height: 15.0pt;">
<td class="xl63" height="20" style="background-color: #3d85c6; height: 15pt; text-align: right;"><div style="text-align: center;">
3</div>
</td>
<td class="xl64" style="border-top-style: none; text-align: right;"><div style="text-align: center;">
300</div>
</td>
<td class="xl64" style="border-left-style: none; border-top-style: none; text-align: right;"><div style="text-align: center;">
200</div>
</td>
<td class="xl64" style="border-left-style: none; border-top-style: none; text-align: right;"><div style="text-align: center;">
150</div>
</td>
</tr>
<tr height="20" style="height: 15.0pt;">
<td class="xl63" height="20" style="background-color: #3d85c6; height: 15pt; text-align: right;"><div style="text-align: center;">
4</div>
</td>
<td class="xl64" style="border-top-style: none; text-align: right;"><div style="text-align: center;">
400</div>
</td>
<td class="xl64" style="border-left-style: none; border-top-style: none; text-align: right;"><div style="text-align: center;">
266</div>
</td>
<td class="xl64" style="border-left-style: none; border-top-style: none; text-align: right;"><div style="text-align: center;">
200</div>
</td>
</tr>
<tr height="20" style="height: 15.0pt;">
<td class="xl63" height="20" style="background-color: #3d85c6; height: 15pt; text-align: right;"><div style="text-align: center;">
5</div>
</td>
<td class="xl64" style="border-top-style: none; text-align: right;"><div style="text-align: center;">
500</div>
</td>
<td class="xl64" style="border-left-style: none; border-top-style: none; text-align: right;"><div style="text-align: center;">
333</div>
</td><td class="xl64" style="border-left-style: none; border-top-style: none; text-align: right;"><div style="text-align: center;">
250</div>
</td>
</tr>
<tr height="20" style="height: 15.0pt;">
<td class="xl63" height="20" style="background-color: #3d85c6; height: 15pt; text-align: right;"><div style="text-align: center;">
10</div>
</td>
<td class="xl64" style="border-top-style: none; text-align: right;"><div style="text-align: center;">
1000</div>
</td>
<td class="xl64" style="border-left-style: none; border-top-style: none; text-align: right;"><div style="text-align: center;">
666</div>
</td>
<td class="xl64" style="border-left-style: none; border-top-style: none; text-align: right;"><div style="text-align: center;">
500</div>
</td>
</tr>
<tr height="20" style="height: 15.0pt;">
<td class="xl63" height="20" style="background-color: #3d85c6; height: 15pt; text-align: right;"><div style="text-align: center;">
15</div>
</td>
<td class="xl64" style="border-top-style: none; text-align: right;"><div style="text-align: center;">
1500</div>
</td>
<td class="xl64" style="border-left-style: none; border-top-style: none; text-align: right;"><div style="text-align: center;">
1000</div>
</td>
<td class="xl64" style="border-left-style: none; border-top-style: none; text-align: right;"><div style="text-align: center;">
750</div>
</td>
</tr>
<tr height="20" style="height: 15.0pt;">
<td class="xl63" height="20" style="background-color: #3d85c6; text-align: right;"><div style="text-align: center;">
20</div>
</td>
<td class="xl64" style="border-top-style: none; text-align: right;"><div style="text-align: center;">
2000</div>
</td>
<td class="xl64" style="border-left-style: none; border-top-style: none; text-align: right;"><div style="text-align: center;">
1333</div>
</td>
<td class="xl64" style="border-left-style: none; border-top-style: none; text-align: right;"><div style="text-align: center;">
1000</div>
</td>
</tr>
<tr height="20" style="height: 15.0pt;">
<td class="xl63" height="20" style="background-color: #3d85c6; height: 15pt; text-align: right;"><div style="text-align: center;">
50</div>
</td>
<td class="xl64" style="border-top-style: none; text-align: right;"><div style="text-align: center;">
5000</div>
</td>
<td class="xl64" style="border-left-style: none; border-top-style: none; text-align: right;"><div style="text-align: center;">
3333</div>
</td>
<td class="xl64" style="border-left-style: none; border-top-style: none; text-align: right;"><div style="text-align: center;">
2500</div>
</td>
</tr>
<tr height="20" style="height: 15.0pt;">
<td class="xl63" height="20" style="background-color: #3d85c6; height: 15pt; text-align: right;"><div style="text-align: center;">
100</div>
</td>
<td class="xl64" style="border-top-style: none; text-align: right;"><div style="text-align: center;">
10000</div>
</td>
<td class="xl64" style="border-left-style: none; border-top-style: none; text-align: right;"><div style="text-align: center;">
6666</div>
</td>
<td class="xl64" style="border-left-style: none; border-top-style: none; text-align: right;"><div style="text-align: center;">
5000</div>
</td>
</tr>
<tr height="20" style="height: 15.0pt;">
<td class="xl63" height="20" style="background-color: #3d85c6; height: 15pt; text-align: right;"><div style="text-align: center;">
150</div>
</td>
<td class="xl64" style="border-top-style: none; text-align: right;"><div style="text-align: center;">
15000</div>
</td>
<td class="xl64" style="border-left-style: none; border-top-style: none; text-align: right;"><div style="text-align: center;">
10000</div>
</td>
<td class="xl64" style="border-left-style: none; border-top-style: none; text-align: right;"><div style="text-align: center;">
7500</div>
</td>
</tr>
<tr height="20" style="height: 15.0pt;">
<td class="xl63" height="20" style="background-color: #3d85c6; height: 15pt; text-align: right;"><div style="text-align: center;">
200</div>
</td>
<td class="xl64" style="border-top-style: none; text-align: right;"><div style="text-align: center;">
20000</div>
</td>
<td class="xl64" style="border-left-style: none; border-top-style: none; text-align: right;"><div style="text-align: center;">
13333</div>
</td>
<td class="xl64" style="border-left-style: none; border-top-style: none; text-align: right;"><div style="text-align: center;">
10000</div>
</td>
</tr>
</tbody></table>
<br /><div style="text-align: left;">
Now is this some kind of be-all-end-all chart? No, but it's a good place to start and a good place to see if you've really screwed up or not. You can also see some of the trouble of using bits with lots of flutes on aluminum. Aside from troubles clearing chips before the next cutting surface comes around: if your machine isn't very fast it's difficult to move forward fast enough to do more than burnish the aluminum away. </div>
<div style="text-align: left;">
<br /></div>
<div style="text-align: left;">
So there's a really simple "this is the sort of feeds and speeds that make sense for milling aluminum" chart I wish I'd found really early on. I might not have been grinding away with a 4 flute 1/4" bit at 0.5ipm and 1500rpm trying to get the darn machine to settle. Oops.</div>
<div style="text-align: left;">
<br /></div>
<div style="text-align: left;">
Lots of really good in depth stuff is <a href="http://www.cnccookbook.com/CCCNCMillFeedsSpeeds.htm">on here as well</a></div>
</center>Spivhttp://www.blogger.com/profile/10510295596753094109noreply@blogger.com0tag:blogger.com,1999:blog-4756137234324004076.post-665740086732746112012-05-10T12:38:00.000-04:002012-05-10T12:38:00.115-04:00Information that will be useful in the future...<b><u>Typical velocities of some insects:</u></b> <br />
Dragonfly: 15.6 mph<br />
Hornet: 12.8 mph<br />
Horsefly: 8.8 mph<br />
Honeybee: 5.7 mph<br />
Housefly: 4.4 mph<br />
Damselfly: 3.3 mph<br />
Scorpion Fly: 1.1 mph<br />
<br />
So that range is ~700 centimeters per second down to ~50 centimeters per second. So somehow I need a response and trigger time somewhere around 1/700th of a second for the fast guys and 1/50th of a second for the slow guys if I'm going to be predicting just where they will be at... uhm... I've said too much already...<br />
<br />
<br />Spivhttp://www.blogger.com/profile/10510295596753094109noreply@blogger.com0tag:blogger.com,1999:blog-4756137234324004076.post-24521622026105926182012-05-08T16:00:00.000-04:002012-05-08T16:00:05.289-04:00What to do with an extra day?Since both parties had an extra day and never got to meet up, what better way to end a rock climbing trip than with more rock climbing?<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-SqlB3Kt8Hcg/TtLiHr4gU_I/AAAAAAAABRk/biamQU9USiI/s640/_DSC0387.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="640" src="http://1.bp.blogspot.com/-SqlB3Kt8Hcg/TtLiHr4gU_I/AAAAAAAABRk/biamQU9USiI/s640/_DSC0387.jpg" width="424" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Stone Summit Climbing Gym, on the north side of Atlanta</td></tr>
</tbody></table>
<br />This place was excellent. Sixty foot ceilings, excellent equipment, and some great climbers. In fact we even ran in to a few people from Aiguille back home!<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-IJEwhAcXCzo/TtLiSGNhjSI/AAAAAAAABSk/7xcrLBxVYj8/s640/_DSC0440.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="640" src="http://1.bp.blogspot.com/-IJEwhAcXCzo/TtLiSGNhjSI/AAAAAAAABSk/7xcrLBxVYj8/s640/_DSC0440.jpg" width="424" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">We climbed till we couldn't.</td></tr>
</tbody></table>
<br />Spivhttp://www.blogger.com/profile/10510295596753094109noreply@blogger.com0tag:blogger.com,1999:blog-4756137234324004076.post-42492951440630753952012-05-06T11:52:00.000-04:002012-05-06T11:52:00.731-04:00and about that fail part...<blockquote class="tr_bq">
<div class="post-title entry-title" itemprop="name">
<i>"More people drop out of distance races due to stomach issues than do from injury"</i></div>
</blockquote>
<div class="post-title entry-title" itemprop="name">
Asleep, then awake, sick as a dog. The one thing I didn't test out beforehand was the prepackaged freeze dried food, and it did not agree with me at all. This marks the coffin for productive work on the trip itself for me. At most I had a couple short climbs on boulders on the way down the mountain, but it was quite over with. We would spend the next night in a hotel.</div>
<div class="post-title entry-title" itemprop="name">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://2.bp.blogspot.com/-x88XNGOIeZs/TtLh_CW34NI/AAAAAAAABQ8/o7Db8SvLURw/s640/_DSC0376.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="424" src="http://2.bp.blogspot.com/-x88XNGOIeZs/TtLh_CW34NI/AAAAAAAABQ8/o7Db8SvLURw/s640/_DSC0376.jpg" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">The long way down. Mike found a super-banana.</td></tr>
</tbody></table>
<div class="post-title entry-title" itemprop="name">
This turned out to be a lucky break in a way; it ended up raining on the mountain the night after we left (Marcus, no tent, freezing rain might not have been so hot), and the second group we were going to meet up with had to cut short and head out early too.</div>
<br />
<br />
Back to Neel's gap:<br />
<br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/-jaInH534bfs/TtLiGtJ2EFI/AAAAAAAABRc/RZPE7AgqgBI/s640/_DSC0384.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="425" src="http://3.bp.blogspot.com/-jaInH534bfs/TtLiGtJ2EFI/AAAAAAAABRc/RZPE7AgqgBI/s640/_DSC0384.jpg" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Neel's Gap: this place felt eerily similar to a Buddhist Sanga. Shoes hang like prayer flags from the tree outside.</td></tr>
</tbody></table>
<br />
<br />
<br />
We had just a couple more stops to make before the final drive home. <br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/-Fxu7b40qx8Y/TtLiB3BrANI/AAAAAAAABRE/ZQZiOdNeShk/s640/_DSC0385.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="http://4.bp.blogspot.com/-Fxu7b40qx8Y/TtLiB3BrANI/AAAAAAAABRE/ZQZiOdNeShk/s400/_DSC0385.jpg" width="265" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">What remained of Mike's hands when we got to the bottom.</td></tr>
</tbody></table>
<br />Spivhttp://www.blogger.com/profile/10510295596753094109noreply@blogger.com0tag:blogger.com,1999:blog-4756137234324004076.post-80321036521597969882012-05-04T10:12:00.000-04:002012-05-04T10:12:00.226-04:00Night Three: Triumph and failure...Thanksgiving is always a time of mixed thoughts for me anyway, and I should assume the same no matter where I am or how removed I may be from 'real life.' On normal years it's a time when family and friends converge. My brothers, nieces, parents, cousins, etc, as well as often those who are part of my family that I am not related to. It's also a reminder of a friend lost, who died trying to rescue a stranger from a car accident. These things happen, and it's not to us to judge them.<br />
<br />
We gathered in our makeshift camp with our makeshift family for Freeze-Dried Thanksgiving Dinner. It was...not good. But the company was great. As the sky found its stars* I packed the astro-gear up and took another climb to the peak. This time it was clear: still below freezing, but bone dry. <br />
<br />
So I'm sitting up there looking at the stars, trying to get my bearings. Great at knowing which way is north, and normally instantly identify all the reference stars...but I'm used to being at sea level. Even on the clearest of clear nights it's nothing like this. After trying to trace from constellation to decide which one was the north star and actually failing (well there goes my astro-cred!) I went for the simplest idea I could think of: take a long exposure sans-tracking:<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="http://4.bp.blogspot.com/-v-V7yaVSBOQ/T6FPEhV2nDI/AAAAAAAAC_A/T0uTpztXzpc/s1600/_DSC0335.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://4.bp.blogspot.com/-v-V7yaVSBOQ/T6FPEhV2nDI/AAAAAAAAC_A/T0uTpztXzpc/s1600/_DSC0335.jpg" /></a></div>
<br />
Well there she is. And with that we were up and running!<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/-FHRC2vFEuDk/T6FPbmts58I/AAAAAAAAC_Q/tPVH2DxfE2s/s1600/7120624771_538b22f463_o.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="640" src="http://4.bp.blogspot.com/-FHRC2vFEuDk/T6FPbmts58I/AAAAAAAAC_Q/tPVH2DxfE2s/s640/7120624771_538b22f463_o.jpg" width="424" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Milky Way, the off season part. But wow that's a lot of stars.</td></tr>
</tbody></table>
And of course, part of the reason I was up there in the first place:<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/-ljMwOyulIQI/T6FP06pi7CI/AAAAAAAAC_Y/d47gZ8QL_vU/s1600/6974543786_38fcea2110_o.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="424" src="http://3.bp.blogspot.com/-ljMwOyulIQI/T6FP06pi7CI/AAAAAAAAC_Y/d47gZ8QL_vU/s640/6974543786_38fcea2110_o.jpg" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Orion Nebula as seen from 4500ft</td></tr>
</tbody></table>
Once I had decided i was frozen enough I packed it up and stumbled back down to camp. <br />
<br />Spivhttp://www.blogger.com/profile/10510295596753094109noreply@blogger.com0tag:blogger.com,1999:blog-4756137234324004076.post-21702278206134524042012-05-02T10:11:00.000-04:002012-05-09T13:36:20.510-04:00Day 2I really need to come up with some more interesting titles for posts. I'll try and make up for it with pretty pictures.<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="http://4.bp.blogspot.com/-IpRp4rnEZpw/TtLjQQZjONI/AAAAAAAABYg/xEWgirlDPHU/s640/_DSC0306.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="640" src="http://4.bp.blogspot.com/-IpRp4rnEZpw/TtLjQQZjONI/AAAAAAAABYg/xEWgirlDPHU/s640/_DSC0306.jpg" width="424" /> </a></div>
<div class="separator" style="clear: both; text-align: center;">
<br /></div>
<div class="separator" style="clear: both; text-align: left;">
Climbing was excellent. The natural rock in this area (the infamous Blood Mountain Boulder Garden) was sharp, but not terrible. Enough to want to tape up our hands. I'm still waiting on my comrads to </div>
get their video stuff together from the day, because I think there was plenty of nice shots taken. I see a couple of shots have been slipped in to <a href="http://vimeo.com/40542429">Marcus's Documentary Reel</a>, but I think there's something a little more focused to come<br />
<br />Spivhttp://www.blogger.com/profile/10510295596753094109noreply@blogger.com1tag:blogger.com,1999:blog-4756137234324004076.post-64329628596349520962012-02-02T07:19:00.002-05:002012-02-02T07:33:45.524-05:00Night through morning...Either the first night was the coldest by a good margin or I got a little more comfortable with the weather as things went on. Either way I'd say the 30 degree Lufama sleeping bag did not keep me warm. I ended up wearing every item of clothing I had taken with me except my shoes and I still had a miserable night. Admittedly it was probably low 20s, but it shouldn't have been so bad.<br /><br />I woke up in the morning feeling less than refreshed, but after bit basking on the rocks and taking in the view I got some heat back in me and was ready to do some climbing. The view, by the way, was gorgeous:<br /><br /><img src="https://lh6.googleusercontent.com/-GEN_AmWzWdQ/TtLjGYfiB6I/AAAAAAAABXw/mfWWnQRjetA/s640/_DSC0211.jpg" /><br /><br />It was time to set up and climb. After scouting around for route ideas we started to set up. I present to you a mountaintop film crew, complete with cranes and dollies:<br /><br /><img src="https://lh6.googleusercontent.com/-06oKSa2Rx_Q/TtLjNgLlJtI/AAAAAAAABYQ/LFDilIdTA-0/s640/_DSC0280.jpg" />Spivhttp://www.blogger.com/profile/10510295596753094109noreply@blogger.com0tag:blogger.com,1999:blog-4756137234324004076.post-90589568776060788712011-12-17T12:01:00.000-05:002011-12-17T12:01:01.341-05:00Night Two: On The PeakLet's hit on which gear en used so far and what was good and bad about it.<br /><br />First my backpack: this was the wrong thing. It stores a lot and is quite comfy, but in expanded mode it puts a lot of weight at a good fulcrum from your body. This isn't a good way to carry a lot and so my strength was my strength. Better choices, by far, for the volumes we were toting would have been things like the Osprey Mike had or the Gregory Marcus had. They distribute the load over a frame and run it vertically to minimize the cantilevered load. <br /><br />The tarptent sublite: excellent. Effortless setup, very light, very compact, and very space conscious. Plenty of space inside too. <br /><br />Hammock tent: Mike's setup was a little heavier but he said it was the most comfortable he has been for being on a frozen peak. <br /><br />Arc'teryx cap and fleece: yes. Long underwear. Two pairs of socks. This tropical native was doing OK at least until nightfall. <br /><br />Now back to story time. After the sun had given us a sufficient show I figured it was time to test out the astro rig. I packed a case, climbed and started to set up. A freezing mist blew over constantly while I did my best in the dark. Aimed at the north Star and clicked on the first shot<br /><br /><center><img src="https://lh5.googleusercontent.com/-I43stMFJj3Q/TupB5Uo9qfI/AAAAAAAABas/LYBqyofuPwE/%25255BUNSET%25255D.jpg width="320" height="212"/></center><br /><br />What?? Flashlight on. The entire rig and camera, lens included, covered in dew and frost. I tried to clean it off and give a few more tries but it was useless. I was shivering and there was no hope of a payout. I packed up and hiked back down to the camp.Spivhttp://www.blogger.com/profile/10510295596753094109noreply@blogger.com0