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12-30-2010, 11:18 AM   #16
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With Ira, I'm assuming that lower ISO is almost always preferred, but my question goes back to Erik's response above where he states that 640ISO is potentially nosier than 800ISO because of the way it is amplified.
So in my example, would 2500ISO be potentially nosier than 3200ISO?
(I'm not understanding why this should be so in the digital realm... It's just a bunch of math!)

12-30-2010, 11:25 AM   #17
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I never heard of a lower ISO being noisier than a high one, but I seldom shoot in the high range, so I'll profess ignorance about that particular claim.
01-02-2011, 02:39 AM   #18
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QuoteOriginally posted by mgvh Quote
Yes, I was using Program mode which I have found helpful as I am learning how to use my K-x. But, even if I was to work full manual, is it really better to use, for example, 2500ISO instead of 3200ISO if hand shake will not be an issue?
Use the lowest possible ISO. It doesn't matter what mode you are shooting, the lowest acceptable ISO results in the best image quality. Personally I always use Av and set the ISO myself - it's how I learnt back in 35mm days.

You must be shooting in a coal hole to need something as high as 3200. Rule of thumb for a fast enough shutter speed is the reciprecol of the focal length, so if the focal length is 100mm then you need a shutter speed of at least 1/100 to hand-hold a shot. IS reduces this a bit but I stick to the old-school values.
01-02-2011, 03:07 AM   #19
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QuoteOriginally posted by mgvh Quote
With Ira, I'm assuming that lower ISO is almost always preferred, but my question goes back to Erik's response above where he states that 640ISO is potentially nosier than 800ISO because of the way it is amplified.
So in my example, would 2500ISO be potentially nosier than 3200ISO?
(I'm not understanding why this should be so in the digital realm... It's just a bunch of math!)
According to Erik, the reason why the lower ISO setting might be noiser is because of the '"digital pushing" to achieve the speeds in between the full stops.' ISO 640 is a half stop, so it may actually be 400 pushed a half stop, as opposed to 800, which is a native full stop.

Though this is the first time I've heard of this. And as Marc Sabatella later points out above your first post, "this sort of thing doesn't matter in practice."

Instead of worrying about noise, let's be concerned more with composition, timing, the subject and light.

01-02-2011, 11:47 AM   #20
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QuoteOriginally posted by mgvh Quote
So in my example, would 2500ISO be potentially nosier than 3200ISO?
My understanding of the theory says no. ISO 2500 will be shot at ISO 1600, and so should start with less noise than ISO 3200. The digital amplification will spread out the pixel values, leaving gaps which may be apparent when looking at a RAW histogram, but won't introduce new noise.

In fact, I don't see how digital pushing can increase noise. It's digital. At most it can amplify the noise that was already there, but it will remain in proportion. Surely?

Last edited by Brangdon; 01-02-2011 at 11:54 AM.
01-03-2011, 07:51 AM   #21
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@catsfive, weatherproof, brangdon: I think you all are right!
Ultimately, what this means is that in the menu, Custom 1, #2, the "Sensitivity Steps" really should be changed from the default (1: EV Step) to 2: As EV Steps.
From my experiments, that setting will regularly allow slightly lower ISOs (eg, 2500 instead of 3200).
Still, I suppose the bottom line is as Marc Sabatella points out above, "this sort of thing doesn't matter in practice."
Now, back to composition, timing, subject, and light....
Thanks all.
01-03-2011, 08:51 AM   #22
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QuoteOriginally posted by mgvh Quote
<snip>Now, back to composition, timing, subject, and light....
Thanks all.
If you need ISO3200 there is previous little light round where you are..
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