martindtm
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Re: RaspberryPi Camera for Astrophotography

Sun Oct 01, 2017 12:11 pm

Question for the group:
Does anyone have a list of the best settings for the camera for astrophotography? When I am trying to focus on a target, due to the latency and the automatic cam settings, it wavers so drastically it is very difficult to find the sweet spot.

gordon77
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Re: RaspberryPi Camera for Astrophotography

Wed Nov 15, 2017 2:37 pm

Here's some pictures of the latest housing in the Pi Display case, and Pi Noir camera on HDMI extension.
Attachments
PiAG in Pi Display.jpg
PiAG in Pi Display.jpg (151.8 KiB) Viewed 900 times
Pi Camera housing2.jpg
Pi Camera housing2.jpg (109.87 KiB) Viewed 900 times
Pi Camera housing.jpg
Pi Camera housing.jpg (124.78 KiB) Viewed 900 times

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ab1jx
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Re: RaspberryPi Camera for Astrophotography

Sun Dec 03, 2017 7:15 pm

Enjoyed skimming this, was looking for examples of what the v 1.3 Pi camera could do with different lenses before I start trying to do it myself.

What would happen if you mounted 2 Pi cameras side by side in the telescope eyetube? Would they be far enough apart to give stereo?
Last edited by ab1jx on Sun Dec 03, 2017 10:34 pm, edited 1 time in total.

gordon77
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Re: RaspberryPi Camera for Astrophotography

Sun Dec 03, 2017 7:39 pm

I think you need something like this...

http://www.rothervalleyoptics.co.uk/cel ... r-125.html

And 2 pi cameras

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ab1jx
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Re: RaspberryPi Camera for Astrophotography

Sun Dec 03, 2017 10:54 pm

Oh, OK, I was just curious because the bare cameras are small enough that 2 would probably fit into a 1-1/4" tube. Somewhere I saw stuff about using 2 for stereo. And the old version 1.3 is going for $8 or less each in places like gearbest.com, dx.com, mininthebox.com. I don't know how you'd arrange them, maybe put 2 of the Sunny boards back to back with the cables coming off at a right angle so the cameras are side by side.

I wasn't impressed with the quality but I expect to have 3 of them in another week or so. I'm not sure how much to blame on the lens. This is completely stock with raspicam and defaults.
picam_2017-10-11_15-36_orig_1024.jpg
picam_2017-10-11_15-36_orig_1024.jpg (98.35 KiB) Viewed 777 times
Compared to a Nikon
DSCN8253_lev_cur_shp_960.jpg
DSCN8253_lev_cur_shp_960.jpg (150.5 KiB) Viewed 769 times


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ab1jx
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Re: RaspberryPi Camera for Astrophotography

Fri Dec 08, 2017 6:19 pm

Just got my 3rd v 1.3 camera and I'm wondering if there are variations in quality between individual cameras. This one seems a lot better than the last. Haven't had it outdoors or devised any good tests yet. Like finding a rare sunny day in December and trying it outdoors with a Macbeth chart https://en.wikipedia.org/wiki/ColorChecker

Fer
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Re: RaspberryPi Camera for Astrophotography

Sat Dec 09, 2017 11:26 pm

ab1jx wrote: Just got my 3rd v 1.3 camera and I'm wondering if there are variations in quality between individual cameras. This one seems a lot better than the last
Most probably, what you're seeing is variations in focus.
Raspberry Camera lens is screwed into mount and then semi-locked in place by Loctite (or something like that).
Since focal length is extremely short (3.6mm if I remember well), a tiny difference in how much the lens was screwed into the mount (during assembly) translates in sensible focus error.
Moreover, from tests it looks like the lens is "factory-focused" at about 2m , while you're trying it outdoors (100m +). Depth of field isn't enough to cover the difference.
When correctly focused, the tiny Raspberry Camera is actually quite capable.

gordon77
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Re: RaspberryPi Camera for Astrophotography

Tue Dec 12, 2017 9:49 am

I've been experimenting with cooling the Pi camera to reduce the noise, so far looks promising...

Sadly it didn't prove sucessful, yes reduced the noise BUT made the pictures unusable, maybe condensation ?
Last edited by gordon77 on Mon Jan 08, 2018 2:17 pm, edited 3 times in total.

gordon77
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Re: RaspberryPi Camera for Astrophotography

Tue Dec 12, 2017 1:58 pm

The cooled pi camera... REMOVED
Last edited by gordon77 on Mon Jan 08, 2018 2:17 pm, edited 1 time in total.

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ab1jx
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Re: RaspberryPi Camera for Astrophotography

Tue Dec 12, 2017 3:52 pm

How cool? Dry ice (-79C) and liquid nitrogen (-195C) https://en.wikipedia.org/wiki/Liquid_nitrogen are both widely used in chemistry, biochemistry, physics. And once you're equipped to handle them they can be surprisingly cheap. I left that job in 1990 but I seem to remember something on the order of $0.50/liter for nitrogen. It's mostly made by big compressors, in this case one college owned one and sold off nitrogen to neighboring colleges essentially at cost. Sort of like the origins of the internet.

Liquid helium (-269C) is expensive enough that we had a substantial amount of plumbing to recover the boiloff. If you're really trying to get close to 0 degrees K that's about the best you can do. Google "optical dewar" for ways to use it. We were mostly passing a light beam through a sample at those temperatures and measuring what came out in a straight line. A few instruments that looked at fluorescence also measured what came off at right angles. Mostly we had cuvettes that were 1 cm on side, not that different from the size of a bare Pi camera.

Dangerous? To a point. Both are very cold so they need gloves. Both are gases trying to regain their gaseous state, so don't confine them in all directions. I use to make liquid oxygen by bubbling oxygen from a tank through copper tubing submersed in liquid nitrogen, then it went into a transparent dewar used in lecture demonstrations to show that it was sky-blue. Most of us handled them every day, thought little of it. Some cameras in astronomy are cooled by these methods, Google it, also "dark current". I worked in chemistry, not astronomy.

Think of the bare camera at the bottom of a test tube pointed up. Lower that into liquid nitrogen, you can still angle it to point at the overhead sky. The obvious problem is going to be the focal length of the lens vs. the length/depth of the test tube. If you don't have a dewar a thermos bottle is close (just don't put the cover on) or maybe about 3 styrofoam cups in a nested stack. Less thermal isolation just means having to replace the nitrogen or dry ice more often.
Last edited by ab1jx on Tue Dec 12, 2017 4:42 pm, edited 2 times in total.

gordon77
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Re: RaspberryPi Camera for Astrophotography

Tue Dec 12, 2017 3:59 pm

Nice idea but a peltier is a bit more practical for me for experimenting :D

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ab1jx
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Re: RaspberryPi Camera for Astrophotography

Tue Dec 12, 2017 4:24 pm

Aw, shoot, I used to drop dry ice into my beer to make a fog and look cool. Tasted awful though.

OTOH, I seem to get about 1 clear night every few weeks, without that I can't do anything.

gordon77
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Re: RaspberryPi Camera for Astrophotography

Sat Dec 16, 2017 12:34 pm

M31, 12 x 3mins, processed in Paint Shop Pro. Sony A6000, Canon 400mm 5.6 guided on NEQ6 by PiAG.
(Looks noisy on here due to resizing)..

Also M42, equipment etc as above...
Attachments
M42.jpg
M42.jpg (55.35 KiB) Viewed 80 times
M31_2.jpg
M31_2.jpg (59.57 KiB) Viewed 130 times
M31.jpg
M31.jpg (59.68 KiB) Viewed 362 times

gordon77
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Re: RaspberryPi Camera for Astrophotography

Mon Jan 15, 2018 2:14 pm

DarkHelmet wrote:
Wed Dec 28, 2016 2:12 am
I just downloaded your Autoguider software and got it up and running using a Celestron Digital Microscope. Next I'll fab an interface board and try it with my CGEM.

Q: How do I "train" the autoguider about the orientation and magnitude of movements? Other autoguider systems go through an orientation process since the guide camera could be at some arbitrary rotation angle relative to RA and Dec axes. Is this done manually with your software?

Thanks!
I finally got around to adding some calibration to the script, consider it beta at present until it's proved. Tried it on a target in the garage, hence the square star below, but I don't expect to see any stars this week due to the weather :( . Note you can't test RA with a fixed target.

Set the star to the centre of the screen , try zoom setting around 4 or 5. Click on the star and then click on Esc (will go yellow) and then click on Dec+/Dec- or RA+/RA-. It will go into CALIB DEC or RA mode, where it will move the telescope for 5 seconds (set by Calibration_time).
When complete it will set 'scale DEC+' and 'scale DEC-' or 'scale RA+' and 'scale RA-'. If there is an error in the aligment of the camera > 5 degs it will show you the amount it needs to rotate (just above R3 button).
Attachments
PiAGr10e7x10.zip
(33.21 KiB) Downloaded 2 times
scr1a.jpg
scr1a.jpg (59.75 KiB) Viewed 44 times
scr2.jpg
scr2.jpg (59.62 KiB) Viewed 44 times

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