Everything in photography is math. Except the creativity.
Apertures are fractions of lens opening in relationship to focal lengths. Every change in aperture or shutter speed is a multiple of the previous (1/2 one way, 2x the other). Perspective of lenses is controlled by field of view (in degrees). Flash range is math (distance affects light levels).
* calculating the fees charged to your clients
* calculating bellows comp
* calculating developing times based upon the lighting ratio of the scene you shot (black and white film only)
