The specs from the D5100 have an actual setting for an ISO value of 100, while the D5000 obtains this in an extended ISO range. Is there any difference in the image quality of these two settings, or is the extended value ISO noisier?
Greg, Nikon has done this for awhile... Olympus just started... using ISO 200 as BASE ISO. What I have seen (and many comments from users) is that the 200 ISO provides the best balance of noise and dynamic range. 100 ISO will give you less noise (whether "extended" ISO or not) but at a very slight loss of dynamic range.
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