Bracketing for use in HDR/Fusion

Aphid

2

« on: 06 / June / 2009, 23:22:59 »

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Firstly let me say that CHDK is absolutely brilliant! A huge thank you to everyone who has contributed to this project! Also my apologies for posting newbie questions.

Anyhow could anyone give me some basic pointers for settings to use in order to get bracketing working for use in HDR/Fusion? I'm using a IXUS55/SD450. At the moment I have gone into custom timer and set a 0sec delay with 3 frames. In CHDK I have set TV bracketing to 2EV and type to +/-. I think that's the right way to do it. Basically I have two questions.

Question 1. Most of the time I am going to be shooting multiple exposures without a tripod and I am going to want to have as short a shutter time as possible and as short a delay between frames as possible. So for the short shutter time I think it would be preferable to use "AV bracketing" rather than "TV bracketing". But for some reason my camera doesn't seem to have the "AV bracketing" function showing. Does anyone know why?

Question 2. From what I can tell bracketing requires a static subject and as such photographing people probably won't deliver good results even if they are sitting in a still pose. Is that right?

I have however heard of some people taking one frame and on the computer artificially creating extra "bracketed" pictures from it and then combining them.

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Microfunguy

4037

Re: Bracketing for use in HDR/Fusion

« Reply #1 on: 07 / June / 2009, 04:50:07 »

Quote from: Aphid on 06 / June / 2009, 23:22:59

for some reason my camera doesn't seem to have the "AV bracketing" function showing. Does anyone know why?

Your camera does not have an aperture diaphragm, just a swing-in/out neutral-density filter.

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From what I can tell bracketing requires a static subject and as such photographing people probably won't deliver good results even if they are sitting in a still pose. Is that right?

Even the tiniest movement of leaves or foliage means that the combined images produce a slightly blurred result.

Quote

I have however heard of some people taking one frame and on the computer artificially creating extra "bracketed" pictures from it and then combining them.

That is with 'proper' raw files as produced by digital SLR cameras.
They can capture a wider dynamic range than the CHDK so-called RAW files.
A single image can be separately 'developed' so that highlights and shadows are nicely exposed and the resulting images then combined.

David

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Aphid

2

Re: Bracketing for use in HDR/Fusion

« Reply #2 on: 08 / June / 2009, 05:51:19 »

Thanks very much for your answer.

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PhyrePhoX

2254
make RAW not WAR

Re: Bracketing for use in HDR/Fusion

« Reply #3 on: 17 / June / 2009, 07:49:44 »

Quote from: Microfunguy on 07 / June / 2009, 04:50:07

That is with 'proper' raw files as produced by digital SLR cameras.
They can capture a wider dynamic range than the CHDK so-called RAW files.
A single image can be separately 'developed' so that highlights and shadows are nicely exposed and the resulting images then combined.

David

i think we had this discussion before. there is no "proper" raw. there is just raw or not raw. the raw pictures chdk produces are raw in it's truest sense. and they also capture a wider dynamic range than the jpgs - and you know that. true, they arent as huge as the dslr counterparts, but still they contain much more information than the jpgs.

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minichanic

7
Maybe 6 feet ain't so far down

Re: Bracketing for use in HDR/Fusion

« Reply #4 on: 18 / June / 2009, 02:17:31 »

If you are shooting handheld- I would definitely recommend shooting raw and processing it at 3 separate exposures (I usually set one that is best for the sky, one for the midground and one for the foreground) using a raw processor.

You can feed the resulting images into photomatix or the free QTPFSGUI, and you know all the photos will be aligned.

Unless you have rock steady arms like the terminator it will be difficult to align them properly. Using this method you can also shoot moving objects.

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