ƒ/Calc is a program for photographers that calculates various lens formulæ. Currently, it understands:
The equations ƒ/Calc uses aren’t secret or difficult. You handled more difficult equations in high school math class, and this manual gives you all the equations.
You may therefore be asking, why use ƒ/Calc if you can do without? Simply, because crunching the numbers by hand is tedious and slow compared to using ƒ/Calc. The faster you can work through a problem, the quicker you can get back to shooting. Or, you can learn several things in the same amount of time as it would have taken you to crunch the numbers for a single problem by hand.
ƒ/Calc also takes into account unit conversions and provides advice on calculated results based on its knowledge of lenses, helping you to avoid mistakes.