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Old May 4, 2006, 5:06 PM   #1
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I just got the S2 IS and am gradually getting used to it. With the help of the manual and lots of experimenting I've answered most of my own questions, but ISO setting still has me stumped.

1) In P, Tv, Av, and M modes, ISO speed can be set. What does the camera do with ISO speed in all the other modes?

2) The P, Tv, and Av modes also have an "auto" ISO speed. What does this do? (In my experiments it doesn't seem to do anything but set the ISO speed to ISO 50.)

Thanks in advance for any help you can give me.
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Old May 4, 2006, 7:55 PM   #2
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For 1 and 2 the camera makes a choice based on the trade off between shutter-speed, possible shake, and quality (and possibly also based on the mode you've selected).

If it is dark, the camera will move toward ISO 400 which is very noisy. I tend to leave in on manual and choose ISO 50 or 100 depending on how dark it is. If I'm desperate I'll move to ISO 200. I've put ISO on the short-cut button. I'll underexpose using exposure compensation before I'll resort to moving to ISO 200.

dunhill wrote:
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I just got the S2 IS and am gradually getting used to it. With the help of the manual and lots of experimenting I've answered most of my own questions, but ISO setting still has me stumped.

1) In P, Tv, Av, and M modes, ISO speed can be set. What does the camera do with ISO speed in all the other modes?

2) The P, Tv, and Av modes also have an "auto" ISO speed. What does this do? (In my experiments it doesn't seem to do anything but set the ISO speed to ISO 50.)

Thanks in advance for any help you can give me.
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Old May 4, 2006, 8:37 PM   #3
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mchnz wrote:
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For 1 and 2 the camera makes a choice based on the trade off between shutter-speed, possible shake, and quality (and possibly also based on the mode you've selected).

If it is dark, the camera will move toward ISO 400 which is very noisy. I tend to leave in on manual and choose ISO 50 or 100 depending on how dark it is. If I'm desperate I'll move to ISO 200. I've put ISO on the short-cut button. I'll underexpose using exposure compensation before I'll resort to moving to ISO 200.

Thanks.

That's what I expected the camera to do but mine seems to do nothing, at least in Tv and Av mode. Perhaps my camera isn't working properly, but no matter... I don't want it setting the ISO speed anyway.

BTW: I've only had limited time for testing, but it appears that some images shot at ISO 400 clean up extremely well. Some of my cleaned ISO 400 images are awfully close to the quality of ISO 50 at 8 X 10 or less, although uncleaned they are awful.
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Old May 5, 2006, 1:02 AM   #4
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If the ISO is on auto, the numeric value isn't reported in the Zoom Browser (the value is just reported as "auto"). So apart from the difference in quality, it is hard to tell what was selected. I suspect the setting might be in the other Canon specific EXIF values somewhere, but I haven't identified it.

p.93 of the manual talks about ISO settings.

What software are you using to cleanup noise?



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Old May 5, 2006, 8:20 AM   #5
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mchnz wrote:
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What software are you using to cleanup noise?



I've only used Noiseware on a handfull of test shots.
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