Ultra Intervalometer, need some help using

d4005

Re: Ultra Intervalometer, need some help using

« Reply #20 on: 12 / August / 2012, 13:53:40 »

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Quote from: blackhole on 12 / August / 2012, 13:21:22

With the program DeepSkyStacker you can use JPEG, and works well with most CHDK RAW files, and of course the DNG files.

Thanks. Downloading now, I'll give it a try. Weird they said on their site that you can work with monochrome images or RAW images.

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d4005

Re: Ultra Intervalometer, need some help using

« Reply #21 on: 12 / August / 2012, 14:48:03 »

Quote from: blackhole on 12 / August / 2012, 13:21:22

With the program DeepSkyStacker you can use JPEG, and works well with most CHDK RAW files, and of course the DNG files.

I gave DeepSkyStacker an hour of my time. I don't think it does what I want. It's a stacker, but I want a NR batch program. One that takes X number of images and applies ONE NR image to all of them, to subtract the noise, and output X modified images. That DeepSkyStacker offers registering (

) and stacking to 16 or 32 bit TIFF files. It offers a batch mode, but also just for making stacked TIFF files.

What I like about the StarTrails program is that it will make movies (even though I could already do that with virtualdub) and that it makes stacking really easy (if I ever want to do it). My main goal now though is to make simple non-stacked non-trailed movies. To do that, I need NR-adjusted images, that were batch NR'ed using one single dark frame image.

I think I need to look into batchifying the BlackFrameNR program. It does the best job of dark frame NR adjustments, if I can just make it batch, it'll be perfect.

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reyalp

13624

Re: Ultra Intervalometer, need some help using

« Reply #22 on: 12 / August / 2012, 15:42:42 »

There are probably some command line programs you could use to batch subtract. dcraw http://www.cybercom.net/~dcoffin/dcraw/dcraw.1.html has dark frame support. I expect it could be done with netpbm http://netpbm.sourceforge.net/ imagemagick http://www.imagemagick.org/script/index.php etc too.

Doing subtraction in the raw (or dng) should give significantly better results than doing it on the jpegs, since it will work with the individual photosites, whereas the jpeg process will spread the bad data out in a way that varies depending on the other content in the image. Of course, shooting raw is slower, takes a lot more card space, and requires you to eventually convert to another format, so YMMV. On the other hand, if you set up your entire workflow as a batch process, that may not be a huge deal.

Another note on darkframes: Ideally, you would have a range of darkframes corresponding to different sensor temperatures. If you take your dark frame at the end of the shooting session, that should give you one close to whatever steady state temperature the camera reached. Or you could make your shooting script log the sensor temp and exposure number to a file, and feed that into your workflow for darkframe selection.

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d4005

Re: Ultra Intervalometer, need some help using

« Reply #23 on: 12 / August / 2012, 17:03:38 »

Quote from: reyalp on 12 / August / 2012, 15:42:42

There are probably some command line programs you could use to batch subtract. dcraw http://www.cybercom.net/~dcoffin/dcraw/dcraw.1.html has dark frame support. I expect it could be done with netpbm http://netpbm.sourceforge.net/ imagemagick http://www.imagemagick.org/script/index.php etc too.

Doing subtraction in the raw (or dng) should give significantly better results than doing it on the jpegs, since it will work with the individual photosites, whereas the jpeg process will spread the bad data out in a way that varies depending on the other content in the image. Of course, shooting raw is slower, takes a lot more card space, and requires you to eventually convert to another format, so YMMV. On the other hand, if you set up your entire workflow as a batch process, that may not be a huge deal.

Another note on darkframes: Ideally, you would have a range of darkframes corresponding to different sensor temperatures. If you take your dark frame at the end of the shooting session, that should give you one close to whatever steady state temperature the camera reached. Or you could make your shooting script log the sensor temp and exposure number to a file, and feed that into your workflow for darkframe selection.

Thanks for those links. I'll try them out tomorrow. You've reminded me to take another dark frame when I shut down this session that's currently shooting away. I did one at the start naturally.

I'll look for a batch RAW -> JPG process also. It's clear that shooting in RAW gives me many more options. I'll have to do a few tests to see how much bigger the RAW files are and if I have enough space to accommodate a long (8 hour) shoot.

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reyalp

13624

Re: Ultra Intervalometer, need some help using

« Reply #24 on: 12 / August / 2012, 18:54:05 »

Quote from: d4005 on 12 / August / 2012, 17:03:38

I'll look for a batch RAW -> JPG process also. It's clear that shooting in RAW gives me many more options. I'll have to do a few tests to see how much bigger the RAW files are and if I have enough space to accommodate a long (8 hour) shoot.

Raw size in bytes is <sensor height>*<sensor width>*<sensor bit depth>/8. For old cameras (like S3) sensor bit depth is 10, for newer cameras (SX40 etc) it's 12. Width and height are slightly larger than the largest possible jpeg. On S3, this comes out to ~7.7MB. DNGs are slightly larger.

For the s3, dcraw should be able to do both the dark frame subtraction and conversion to jpeg. It should be pretty easy to make a batch file or something that does this over all your images.

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d4005

Re: Ultra Intervalometer, need some help using

« Reply #25 on: 13 / August / 2012, 09:40:15 »

Quote from: reyalp on 12 / August / 2012, 15:42:42

There are probably some command line programs you could use to batch subtract. dcraw http://www.cybercom.net/~dcoffin/dcraw/dcraw.1.html has dark frame support. I expect it could be done with netpbm http://netpbm.sourceforge.net/ imagemagick http://www.imagemagick.org/script/index.php etc too.

I didn't like the look of dcraw or netpbm so much, but imagemagick looks amazing. I think I can do many good things with that. Not only the NR, but also pseudo dolly pans with batch crops, and various other batch effects that I would otherwise never have dreamed of. So many times over the last decade or so I've wished I could batchify certain operations. PhotoShop and PhotoPaint (Corel) never really wanted to make that easy. I understand that GIMP is supposed to make it slightly easier, but this imagemagick looks perfect (so far).

Well, I've got my new and improved meteor shower movie made (but still not NR'ed yet). I think I'll wait for the NR processing before I think about uploading it to youtube.

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d4005

Re: Ultra Intervalometer, need some help using

« Reply #26 on: 14 / August / 2012, 04:51:29 »

Got my finished movie uploaded to youtube. Due to my poor bandwidth right now, I could only upload it in 720p HD. It's as good as I expected I'd be able to do with the crappy old S3 iS providing the images. I haven't hacked my SX40HS or S100 yet. Maybe this image quality will motivate me to do so, although I don't think the CHDK versions for those cameras are finished yet anyway. This is at 10FPS (so it's effectively 5 minutes of actual time per second of video).

Here it is: My Meteor Video on Youtube

« Last Edit: 14 / August / 2012, 05:34:21 by d4005 »

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blackhole

856
A590IS 101b

Re: Ultra Intervalometer, need some help using

« Reply #27 on: 14 / August / 2012, 06:22:27 »

Looks good, the exposure is a bit too long, so the stars are elongated. For wide-angle lens, 20 second exposure is the maximum without tracing.
The camera would do better subtract dark frame
You should set up a "Dark frame subtraction" to "ON"

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d4005

Re: Ultra Intervalometer, need some help using

« Reply #28 on: 14 / August / 2012, 07:56:32 »

Quote from: blackhole on 14 / August / 2012, 06:22:27

Looks good, the exposure is a bit too long, so the stars are elongated. For wide-angle lens, 20 second exposure is the maximum without tracing.
The camera would do better subtract dark frame
You should set up a "Dark frame subtraction" to "ON"

Thanks for the suggestions. The first night I was on ISO100 at 32second exposures and I thought it was a bit dark, so the second night I went for ISO400 and that was probably a step too far.

As for setting dark frame subtraction on in the camera, it leads to missing half of the action (and for a meteor shower, potentially half of the meteors). I noticed that after my first attempt. One frame would have part of the meteor trail, and the next frame would have it starting further across (because the middle part of the travel wasn't captured, because it was busy recording it's dark frame).

So I don't think having the camera doing the dark frames for this kind of thing really works. It's fine for a basic star trails type video or lightning, you wouldn't notice the 50% missing action, but for slow moving meteors you definitely do.

I'm gonna remember that 20 second tip though, for non meteor shower videos. I plan to setup during the next night time thunderstorm, and I'll make sure I go for a regular 15 second exposure maximum.

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lapser

1093

Re: Ultra Intervalometer, need some help using

« Reply #29 on: 24 / August / 2012, 22:04:51 »

That was a great video for the light conditions, and using CHDK! It's hard to tell the meteors from satellites and airplanes in a long exposure, though. Airplanes make dotted lines. Satellites are only visible until 2 hours or so after sunset. Meteors are really fast, so they only appear in 1 frame. If it appears in 2 frames, it's not a meteor. I'm not sure any of the streaks on your video were meteors, but it's still pretty cool!

Perseid meteors all project back to the constellation Perseus, hence the name. The peak was on Sunday morning around 2 a.m. because Perseus was well above the horizon, so you could see more meteors going in all directions from Perseus.

I took this video with a Panasonic FZ150 and external timer. I processed the RAW files with Photoshop Lightroom, which does batch processing with a single click. I used an external timer set to 70 seconds, with 30 second exposure time, 30 second dark frame (can't turn off), and 10 second save time.

I took the camera and tripod up to Moraine Lake Friday and started it shooting when I went to sleep. It lasted 2 hours Friday, and I didn't get any definite meteors. After climbing South Sister on Saturday, I had just enough energy left to set up the camera Saturday night with a totally fresh battery. It lasted 4.5 hours and I got lots of true Perseid meteors in the last hour. The camera died right at the peak of the shower, but the moon was rising and washing things out any way. This is in a wilderness area, so the dimmer stars and Milky Way are visible.

Anyway, here's the video I made:

Perseid Meteor Shower - August 10-11, 2012

And here's the brightest definite Perseid meteor I captured. Note that the tail of the meteor is greenish colored as the outer layers of rock start burning off minerals. Then it turns white as it burns up completely.

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