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Message:: [QUOTE="-jeffB, post: 2362821, member: 27832"]A few pictures might be worth a lot of words here. Here's a pretty well-exposed shot, with its histogram:[ATTACH=full]482219[/ATTACH] That big spike corresponds to the cardboard of the 2x2 -- in the full image, it occupies most of the pixels, and it's all mostly the same brightness. There's a tiny spike off at the right, because a very few pixels are overexposed, but they don't really detract from the image. There's also a spike to the left, representing the gap between the coin and the 2x2; I don't care about that gap, so I don't mind that it's underexposed. Here's an underexposed image:[ATTACH=full]482220[/ATTACH] Note that most of the area under the histogram is pushed off to the left. It's not actually clipped off the left -- the pixels haven't gone all the way to zero -- but it looks dark, and it's harder to see detail. Here's an overexposed image:[ATTACH=full]482223[/ATTACH] See the spike to the right? Much of that is the 2x2, which we don't care about, but we're also starting to lose detail in the highlights -- they're getting clipped to the maximum possible value. Here's a badly overexposed image:[ATTACH=full]482224[/ATTACH] Here, most of the histogram's area is shoved over against the right edge. We're losing a great deal of detail in the coin. To maximize visible detail when you're adjusting exposure, you want to see a histogram that's well-distributed, without leaving a lot of empty area to the left or to the right. Keep in mind, though, that there may be areas of the image you don't care about, and pushing them off to the left (if they're dark) or the right (if they're bright) is fine.[/QUOTE]

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