SX110 IS / SX10 IS ISO <80

YujiSato

2

« on: 28 / September / 2010, 11:31:51 »

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Hello,

I've been using CHDK in my SX110 IS for like 2 months, enjoying all the improvements to my camera and I'm still experimenting with them.

As of last, I've tried doing some daylight long-exposure photography in a beach. Unfortunately, although I could reduce the light a lot through lowering my aperture from 8 to 16, I didn't notice any effect from lowering the ISO to less than 80. I have already tested higher ISOs (1600-8000 for night long-exposure photos), with success.

A friend of mine had a SX10 IS, which I had just installed CHDK into, and he also didn't notice any improvement in the lower ISOs.

However, the CHDK wiki specs(http://chdk.wikia.com/wiki/CameraFeatures) tells that our camera models do make ISO 10 photos.

Does anyone have a light on anything that we could be doing wrong or if our models are capped to ISO 80?

Thanks if anyone can help, I'd really like to have ISO 10 in my camera..

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reyalp

14119

Re: SX110 IS / SX10 IS ISO <80

« Reply #1 on: 28 / September / 2010, 12:23:42 »

ISO significantly lower than the canon factory limit has never been proven to work. The claims of 10 are almost certainly a result of sloppy testing. See http://chdk.setepontos.com/index.php/topic,3373.0.html for an example of proper testing. While I generally try to avoid changing entries a I can't confirm, at this point maybe we should.

Someone should make an override testing script that logs shot_histogram data in a standard format (I suggest CSV), then we could plot the cameras actual behavior with some confidence. The only pre-condition should be fairly constant illumination, and that could be sanity checked with Bv. (edit, well, you'd want a relatively low contrast scene, and illumination in a reasonable range...)

« Last Edit: 28 / September / 2010, 12:27:19 by reyalp »

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Don't forget what the H stands for.

vit40

276

Re: SX110 IS / SX10 IS ISO <80

« Reply #2 on: 28 / September / 2010, 12:36:29 »

About a year ago, I'v been making some testing with girlfriend's SX110 and from my remembering lowest 'working' ISO was about 64. Below that, result is only that camera is fooled that ISO is lower, so it meters longer exposures than needed and images are overexposed (unless you raise negative exposure correction to compensate)

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