Q) When I bump up the ISO setting in my camera, am I changing its sensitivity? If it does, couldn’t I just leave it there and adjust my aperture or shutter speed?
S.P., Via the Internet
A) If it were only that easy… Adjusting your camera’s ISO amplifies the small voltages coming from the image sensor. When you amplify a signal, you also amplify the noise that’s inherent in any electrical signal.
The lower the ISO setting, the lower the noise in your image. That’s not to say there aren’t great images captured with a high ISO setting, because there are. But if you have the choice to use a low ISO or a high one, choose the lower one.