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Anonymous
>>72778 Sure.
First of all, see Wikipedia excerpt from article "Film speed" - "Film speed is found by referencing the Hurter–Driffield curve, or D–logE curve, for the film. This is a plot of optical density vs. log of exposure (lux-s). There are typically five regions in the curve: the base + fog, the toe, the linear region, the shoulder, and the overexposed region. Following the curve to the point where density exceeds the base + fog by 0.1, find the corresponding exposure. Dividing 0.8 by that exposure yields the linear ISO speed rating."
In layman's terms, this is a fancy guideline for figuring out at which exposure a very small difference in light (0.1) can be measured.
Nikon's guideline is to set the default ISO (sensitivity) to the one that gives the best measurement in terms of signal to noise. For the D300, Nikon's experiments probably showed that the best signal-to-noise ratio happened at ISO 200 sensitivity. They set this as default and rename ISO 100 to "LO 1" to reduce the confusion from people who do not understand how it works and assume that ISO 100 will always give them the smoothest possible picture from the camera.
Unfortunately it also turns away people who assume that it's inability to do ISO 100 is a flaw. It's a tough thing to explain this kind of stuff to most consumers, it's like trying to explain how Intel's new 2.8 Ghz processor is better than their older generation 3.0 Ghz processor.
Then there's other people who think it's awesome because you're getting the best possible performance out of the camera at higher ISOs. Also a fallacy.
So keep in mind, it's neither a flaw nor a feature yet. We'll only know for sure after we see good samples from the D300.
As far as Lo 1 and Hi 1: They get these by modifying the signal AFTER exposure. The disadvantage is that a Lo 1 (ISO 100) picture is not going to be any smoother than an ISO 200 picture on the D300 (it may even be slightly degraded in comparison).
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