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Ultra Intervalometer, need some help using

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Offline d4005

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Re: Ultra Intervalometer, need some help using
« Reply #10 on: 11 / August / 2012, 15:59:46 »
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Quote from: peter.pashen on 11 / August / 2012, 14:39:33
if it works i want to see those meteor shower pics :)
All setup and shooting now :)

Got my Ricoh R8 shooting 8 second exposures every 10 seconds on it's built-in intervalometer.

My CHDK'ed Canon S3 iS is shooting 32 second exposures via exposure override. It's using the ultra intervalometer with zero values for intervals, so that it shoots effectively continuously.

I'm disappointed with the Canon's recovery time. After a 32 second exposure, it takes about 30 seconds before it's ready to shoot another. At this point the intervalometer sees it's ready and starts the next shot. It's definitely not the intervalometer's fault, it happens without it.

Anyone know why it takes 30 seconds to process a 32 second exposure? It's not like it's having to merge images, it's just one. It's not like the image is any larger than a 1 second exposure. Whatever processing is being done, I don't understand why it takes any longer depending on how long the shot was. It can't be doing 30 seconds worth of noise processing can it?
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Still around but unused: Canon S3 iS (*CHDK*), Canon G11 (loaned out), Casio EX-FS10
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Offline waterwingz

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Re: Ultra Intervalometer, need some help using
« Reply #11 on: 11 / August / 2012, 16:02:51 »
Quote from: d4005 on 11 / August / 2012, 15:59:46
Anyone know why it takes 30 seconds to process a 32 second exposure? It's not like it's having to merge images, it's just one. It's not like the image is any larger than a 1 second exposure. Whatever processing is being done, I don't understand why it takes any longer depending on how long the shot was. It can't be doing 30 seconds worth of noise processing can it?
Yup - its doing noise reduction (dark frame subtraction). Canon kicks that in automatically when you shoot longer than a couple of seconds.  You can disable it in the CHDK menus - its in the RAW menu (and it happens regardless of whether you are actually shooting RAW or not).


« Last Edit: 11 / August / 2012, 16:06:27 by waterwingz »
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Offline outslider

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Re: Ultra Intervalometer, need some help using
« Reply #12 on: 11 / August / 2012, 16:09:47 »
Yes - and the reason the time of that proces is same as the shoot itself is because camera in fact takes two photos - one that you want and the second with closed shutter - to acquire .the noise.
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Offline d4005

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Re: Ultra Intervalometer, need some help using
« Reply #13 on: 11 / August / 2012, 16:45:37 »
Thanks for the noise tip (raw menu). Lucky I'm only an hour into the shoot. Quick mod to turn the noise off now :)

edit: done! No more big gaps :)

Hoping I don't wake up to a thousand black pictures.
« Last Edit: 11 / August / 2012, 16:54:48 by d4005 »
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Still around but unused: Canon S3 iS (*CHDK*), Canon G11 (loaned out), Casio EX-FS10
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Offline d4005

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Re: Ultra Intervalometer, need some help using
« Reply #14 on: 12 / August / 2012, 03:23:22 »
Well, I learned a lot on my first overnight time-lapse.

I learned that an 8 second exposure isn't worth doing. Luckily this was just a backup (second camera) option that I figured might be worth doing in parallel with my CHDK shoot. It wasn't.

I learned (from this thread) that whatever exposure length you're using, the camera (unless told not to) will do an equal length exposure with the shutter closed for noise difference reduction.

I learned that if you turn off the noise reduction on a 32 second exposure, you get a noisy image :-) Quite a lot of red and blue pixels scattered around (I know they're not stars/planets because they don't move).

I learned that there's no perfect solution for that noise problem. I either miss 50% of the action because I'm busy exposing for noise half the time, or, well there is no or. The noisy images aren't much use at all. I did see something in the RAW options about "first time". Maybe there's a way of taking one reference noise shot and applying it to all subsequent images. Will need to investigate, unless someone here can tell me that's not what that is.

I learned that after an all-night shoot (about 8 hours worth), the uncropped video I made from it using virtual dub was 65 gigabytes. Not exactly youtube friendly. Xvid compression makes the movie not worth looking at, although size wise it's nice. Lots of options here though, change image size in camera, resize, crop [and pan for dolly effect].

I learned that next time I'll use a 64 second exposure. Quite a few of my meteors weren't caught in one single (32 second) image. Plus I think twice the brightness would be nice.

Anyway, here's a 7MB animated GIF of some of the highlights.

This has made me even more impressed by some of those fantastic time lapse sky movies you see on vimeo made in the desert. Those guys really have their techniques sorted (and aren't using a Canon S3 iS either :) ). A nice F1.8 lens would be lovely, but I don't justify buying myself expensive camera equipment, I'm not good enough to deserve it  :(
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Offline reyalp

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Re: Ultra Intervalometer, need some help using
« Reply #15 on: 12 / August / 2012, 04:27:08 »
Quote from: d4005 on 12 / August / 2012, 03:23:22
I did see something in the RAW options about "first time". Maybe there's a way of taking one reference noise shot and applying it to all subsequent images. Will need to investigate, unless someone here can tell me that's not what that is.
It's not. It means only take raw for the first image when shooting in continuous mode.

However, you can make your own dark frame and subtract it from your images later on your PC.
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Offline d4005

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Re: Ultra Intervalometer, need some help using
« Reply #16 on: 12 / August / 2012, 07:34:36 »
Quote from: reyalp on 12 / August / 2012, 04:27:08
Quote from: d4005 on 12 / August / 2012, 03:23:22
I did see something in the RAW options about "first time". Maybe there's a way of taking one reference noise shot and applying it to all subsequent images. Will need to investigate, unless someone here can tell me that's not what that is.
It's not. It means only take raw for the first image when shooting in continuous mode.

However, you can make your own dark frame and subtract it from your images later on your PC.
Good point. I could make my own reference image with the lens cap on. I just discovered the blackframe_NR program. I'll be doing that next time (tonight maybe with 64 second exposures).

Does anyone know how to use the BlackFrame_NR program in batch mode? It does exactly what I want, but it does it image by image one at a time.
« Last Edit: 12 / August / 2012, 09:11:11 by d4005 »
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Still around but unused: Canon S3 iS (*CHDK*), Canon G11 (loaned out), Casio EX-FS10
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Offline waterwingz

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Re: Ultra Intervalometer, need some help using
« Reply #17 on: 12 / August / 2012, 11:22:01 »
Quote from: d4005 on 12 / August / 2012, 07:34:36
Does anyone know how to use the BlackFrame_NR program in batch mode? It does exactly what I want, but it does it image by image one at a time.
I don't think BlackFrame_NR was written with batch processing in mind.  So I did some googling for "dark frame subtraction".  There is a lot of information out there !

Found this - it looks interesting and close to what you want to do :  http://www.startrails.de/html/software.html

also this : http://deepskystacker.free.fr/english/index.html

and finally : http://ufraw.sourceforge.net/Guide.html  (which has a batch mode).
« Last Edit: 12 / August / 2012, 11:26:04 by waterwingz »
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Offline d4005

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Re: Ultra Intervalometer, need some help using
« Reply #18 on: 12 / August / 2012, 12:55:40 »
Thanks WW. I've had good NR results with the BlackFrameNR program. Give it a good darkframe and it really works well. Not batchable though of course.

Using the same darkframe with the startrails program though seemed to have no effect. Bit disappointed with it's NR feature, but the startrails and movie-making features are of course excellent. You just need to feed it pre-NR-processed images and it's great.

The UFRAW only works with raw images unfortunately. Same with the deepskytracker (either monochrome or RAW).

The problem with working with RAW images (for me) is that at the end of all the processing, I'm still going to have a bunch of RAW files. I'll need a further batch process to convert them all to jpegs.
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Offline blackhole

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Re: Ultra Intervalometer, need some help using
« Reply #19 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.
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