Quote Originally Posted by andnowimbroke


I get that high ISO increases noise (especially in black areas). Most people even shoot with an increase in exposure compensation to help avoid shadowy area (rather than just balancing exposure because of what's in the scene) but not too much to blow highlights out really bad. Doesn't raising your exposure comp justchange one of your settings (A/S/ISO speeds)? If your in a dark place where you are already playing with your limits (100mm lens @F4 set to ISO800 with 1/75sec shutter speed, how is adjusting the comp going to keep down high ISO noise in the shadows? The Ex.comp is going to want to make it brighter by adjusting something which might lead to a softer, blurry, or noisy picture. I read this thing twice and it makes more sense in my head than in writing. If you understood it, help me out. I know I'm missing sumthung.


I think a lot of this depends on your approach and objective. If you start from scratch and decide "I want to take this shot at f/4.5 because that gives the DoF I want", a truly regimented photographer might set their camera for Av f/4.5 and ISO100, then take a test shot. At this point, we have two variables we need to adjust: exposure comp and ISO. Theoretically, the initial preview should be sufficient to adjust exposure comp to preserve shadows while not sacrificing important highlight detail. That leaves only one adjustment, ISO, and the ISO will likely be increased until you achieve a non-shaky shutter speed, a stop-action/artistic shutter speed, a combination of both, or a reasonable tradeoff given the realities of physics and what's in your hand.


If you look at it from another angle, although increasing exposure comp might lead to a softer, blurry, and/or noisy picture, it's extending the shutter time (if everything else stays the same and you're in Av), and that's going to decrease noise in the shadows (you're giving the sensor more photons courtesy of more time).