Exposure calculation
The exposure of a scene is dependent on three main values :-
1. Aperture, increasing or decreasing you aperture will vary your
DOF, depth of field (zone of focus).
2. Shutter speed, increasing or decreasing will determine how
moving objects are perceived in a scene blur or sharp.
3. ISO, increase or decrease will determine how much noise will
be in the captured image.
Secondary to these three values is your EV - exposure
compensation and is measured in stops i.e. -3 -2 -1 0 +1 +2 +3
Here is the exposure triangle to show how the Aperture, shutter speed
ISO ans EV are related to each other.
Below are some of the affects of varying these four values.