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fixedint.lua: Astrophotography oriented script for long exposure + timelapse

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Offline reyalp

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Posting a script I've been developing and using for a while for satellite passes and astrophotography.

This script shoots one or more shots at a constant exposure. It is primarily intended for astrophotography, either single long exposure shorts, sequences for "stacking", or timelapse. It is distantly related to Meteor Intervalometer, but is optimized for my particular workflow.

Wiki page with details and download link:
http://chdk.wikia.com/wiki/Lua/Scripts:_Fixed_Exposure_Intervalometer

Please post bug reports, suggestions and questions here.

If you do something cool with it, posting in creative uses of CHDK section is encouraged.

Update history
May 6 2018 - v1.3
  • Added options to start at a particular clock time
  • Added options for zoom and focus distance
  • Fixed problems with long intervals
Jan 5 2016 - v1.2
  • re-uploaded 1.2 with the correct files  :-[
Jan 3 2016 - v1.2
  • Fixed the interval setting being ignored and "sleep" log column not being logged
« Last Edit: 07 / May / 2018, 01:50:48 by reyalp »
Don't forget what the H stands for.

I just downloaded your script and tried it out. I'm trying to get it to take 30 second exposures about 5 seconds apart for a star movement time lapse.

Which settings do I set in the script menu once I load the script? Do I also need to set the override Tv to long exposures in enhanced photo settings? Where in the script menu do I set the # of seconds?

I'm using an A495 camera, and I've not used CHDK for anything other than simple intervalometer daytime shots before, letting the camera pick the settings.   


thanks

update - I found the setting to set the # of seconds exposure, I initially set the Tv setting to 32 and I would get one long exposure then each after that would be short. I finally figured out I needed to set the canon setting to continuous AND have the continuous set in the script menu to get continuous long exposures.
« Last Edit: 04 / January / 2016, 00:33:49 by Glenstr »

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Offline reyalp

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I just downloaded your script and tried it out. I'm trying to get it to take 30 second exposures about 5 seconds apart for a star movement time lapse.

Which settings do I set in the script menu once I load the script? Do I also need to set the override Tv to long exposures in enhanced photo settings? Where in the script menu do I set the # of seconds?
You should set shutter speed in the script menu.

Set Tv to 32 (or Tv to 0 and Tv + sec to 30 if you want exactly 30)

Set the interval to something like 350 (30 sec exposure, 5 sections in between). If you are shooting raw, saving / processing time may be close to 5 sec.

If you want 5 sec between exposures, you'll need to turn "Disable Canon Dark frame on", otherwise a 30 sec exposure will take 60+ seconds.
Don't forget what the H stands for.

I just downloaded your script and tried it out. I'm trying to get it to take 30 second exposures about 5 seconds apart for a star movement time lapse.

Which settings do I set in the script menu once I load the script? Do I also need to set the override Tv to long exposures in enhanced photo settings? Where in the script menu do I set the # of seconds?
You should set shutter speed in the script menu.

Set Tv to 32 (or Tv to 0 and Tv + sec to 30 if you want exactly 30)

Set the interval to something like 350 (30 sec exposure, 5 sections in between). If you are shooting raw, saving / processing time may be close to 5 sec.

If you want 5 sec between exposures, you'll need to turn "Disable Canon Dark frame on", otherwise a 30 sec exposure will take 60+ seconds.

Thanks, I didn't see your reply before I edited my OP.  As I write this I've got it shooting the stars at 32 second exposures - it took me awhile to figure out that I needed to set the Canon setting to continuous as well, before I did that I was getting one long exposure, then all exposures after that were short. Once I set the continuous on and checked it in the script menu it seemed to work ok.

I'm assuming I don't need to set the override Tv to long exposures in the CHDK enhanced photo features now.


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Offline reyalp

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Thanks, I didn't see your reply before I edited my OP.  As I write this I've got it shooting the stars at 32 second exposures - it took me awhile to figure out that I needed to set the Canon setting to continuous as well, before I did that I was getting one long exposure, then all exposures after that were short. Once I set the continuous on and checked it in the script menu it seemed to work ok.
That's odd. It should work without continuous set in the Canon firmware, normally it would just be a bit slower.

If you can post the log file from a run with this problem, that might help me understand the issue. It's saved in fixedint.csv in the root of the SD card.
Don't forget what the H stands for.

I tried it a couple of times and I could not get it to do continuous long exposures until I set the canon setting. Perhaps it's unique to the A495? I have a couple of A490's too I can try it in.  I'm using 1.4.1-4319 CHDK.

Anyway, here is the log file attached to this message. I just made a short movie from the short session I did, I'm getting a lot of amp glow from this camera, so I may experiment with the dark frame settings some more, and I'm also just shooting jpg in this trial.

Also attached the short timelapse I just did - looking forward to doing some more when I get more time - it's late now and I'm calling it a night for now.

thanks for your help.

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Offline reyalp

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I tried it a couple of times and I could not get it to do continuous long exposures until I set the canon setting. Perhaps it's unique to the A495? I have a couple of A490's too I can try it in.  I'm using 1.4.1-4319 CHDK.
It could be a camera specific bug. A quick test on my d10 worked in both continuous and non-continuous mode. If the camera is not in continuous mode, the script should fall back to the regular mode even if the option is checked.

I do see a bug in my logging code, the "sleep" value isn't logged.
edit:
This bug actually made it ignore the interval completely. I don't think this would have caused your problem, but I've fixed it updated the wiki page to point at the new version.

Quote
I just made a short movie from the short session I did, I'm getting a lot of amp glow from this camera, so I may experiment with the dark frame settings some more, and I'm also just shooting jpg in this trial.
Yeah, on an older camera like this you will want dark frames for anything more than a few seconds.

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Also attached the short timelapse I just did - looking forward to doing some more when I get more time - it's late now and I'm calling it a night for now.
Aside from the amp glow that looks good :)
« Last Edit: 04 / January / 2016, 01:49:55 by reyalp »
Don't forget what the H stands for.

Thanks - I may look at getting a better model that'll take CHDK at some point - I picked up the A490 and A495 because they were dirt cheap, have no IS and work great for aerial photography, especially on multirotors. I just thought I'd try them for night time lapses since I already have the CHDK with them. 

I'll try it with dark frames enabled - but unless I'm mistaken, aren't dark frames more for use with long exposures stacked for one clear image, not so much with time lapses?

I've also  got a NEX-5N with the Tempus/Astrus remote as well for time lapses, and my wife has an A5100 Sony that I think I can get a time lapse app for -  but it's fun playing with the CHDK capabilities on these Canons.

When you say the bug you found made it ignore the interval - exactly how?  And on your D10 it doesn't matter what you set the continuous option (on Canon firmware) to it will still take continuous long exposures?   


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Offline reyalp

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Thanks - I may look at getting a better model that'll take CHDK at some point - I picked up the A490 and A495 because they were dirt cheap, have no IS and work great for aerial photography, especially on multirotors. I just thought I'd try them for night time lapses since I already have the CHDK with them. 
FWIW, in this case it's more a matter of newer than cheaper. I don't know where the exact cut-off is, but neither my elph130 or sx160 suffer from amp glow much.
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I'll try it with dark frames enabled - but unless I'm mistaken, aren't dark frames more for use with long exposures stacked for one clear image, not so much with time lapses?
Dark frames are good for reducing the effects of amp glow and hot pixels, regardless of how you will use the final image.

If you enable canon dark frame subtraction on the camera, there will be a big gap between each shot, because the canon firmware will do a dark frame of equal length after each exposure.

To avoid this, you need a way to do the subtraction on each frame before making the video. I have done this using raw therapee batch processing (this clip https://app.box.com/files/0/f/3350614644/1/f_46635641505 for example). For best results, you will want to use RAW, but I believe raw therapee will let you dark frame jpegs. Shooting raw will also cause some gap between frames, because it takes several seconds to save on cameras like this.

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When you say the bug you found made it ignore the interval - exactly how?
It would just shoot the next shot as soon as the previous one was finished. So if you set a 4 second exposure and a ten second interval, it would still shoot once every 4 seconds (+ processing / saving time). I reorganized some stuff before posting that version and didn't test thoroughly :-[

This doesn't affect the exposure length though. If I've understood your problem correctly, you set a 32 second exposure, but after the first shot, the actual exposure is shorter?
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And on your D10 it doesn't matter what you set the continuous option (on Canon firmware) to it will still take continuous long exposures?   
Yes.
Don't forget what the H stands for.

Thanks - you've given me some homework.  One thing I'm wondering about is if I enable dark frames then I'm going to get a bigger gap between exposures, resulting in a less smooth movie for the time lapse, unless what you said about the raw therapee program addresses this.

And do I need to uncheck the "disable canon dark frame" and check the "make dark frames" in the script options?  I don't think the Canon firmware on this camera has dark frame subtraction as an option. 

I'm still using your unfixed script - I was sure the 5 second interval was working, but I'll check when I use it again.

I'll try with some raw files next time, and maybe a lower ISO than 1600 to see if I can get the noise down a bit.

I just ran out my batteries trying it out again (with the old script), same settings as last night. Pretty pleased with the results, even caught a satellite (or plane) this time. I got just over an hour this time, batteries don't last long outside now as it's -15C out right now.

 

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