There’s a camera setting called “ISO” which determines how sensitive your camera is to light. The higher the ISO, the less light you need to take a picture. The downside is you get more “noise”, which is a grainy look to the picture. This isn’t always a bad thing, if you are trying to simulate an old-style film look. Modern software can reduce much of this noise. I use Adobe Lightroom (this is not a paid plug, it’s just what I use).
On a Canon (also not a paid plug, its just what I use), the lowest ISO (i.e. the least noise) is typically 100, although newer cameras go down to 50. Generally speaking, the lower the ISO the better to get the cleanest possible image. The technology on current cameras has gotten so good that you can get reasonable images with higher ISOs which were impossible to achieve 10 years ago.
While I was meditating yesterday, I wanted to capture this image using only the light from the candle. I loved the shadow it was producing on the buddha. I had to shoot this at ISO 25,600, which is a ridiculously high ISO. Check out the results: not bad at all!
