Utility of using low ISO (E.g., ISO-16)

cboshuizen

« on: 01 / June / 2010, 21:55:25 »

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Hi guys, my first post here.

So, I am using the development version of CHDK on the G11. It works pretty well! I've noticed that I can set the ISO as low as 16, and it takes a picture. First off, is it really doing ISO-16? If it is, would I expect to see the same improvement in noise that I would in a film camera at the same ISO? What would be a good lighting or compositional arrangement in which to test this for myself?

Thanks!
Chris

« Last Edit: 01 / June / 2010, 22:50:12 by cboshuizen »

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reyalp

14118

Re: Utility of using low ISO (E.g., ISO-16)

« Reply #1 on: 01 / June / 2010, 22:44:18 »

Quote from: cboshuizen on 01 / June / 2010, 21:55:25

So, I am using the development version of CHDK on the G11. It works pretty well! I've noticed that I can set the ISO as low as 16*, and it takes a picture. First off, is it really doing ISO-16?

No, it's most likely not.

I'm not aware of any credible measurement of ISO below the factory lower limit.

See http://chdk.setepontos.com/index.php/topic,3373.0.html for a rigorous test on a570.

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Don't forget what the H stands for.

cboshuizen

Re: Utility of using low ISO (E.g., ISO-16)

« Reply #2 on: 02 / June / 2010, 01:16:16 »

Thanks, that is a great review. I repeated my own limited test, and the photos were essentially identical. The real cue is that the exposure values are identical, which they shouldn't be at lower amplifier gains.

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