Currently the industry uses the old 35mm film standard as the baseline for measuring sensor sizes, most colloquially known as full-frame. Some calculations are straight forward, like converting a 4/3 sensor to 35mm-equivalent (multiply the focal length by 2) or APS-C sensors like those found in a Fujifilm X-mount camera (multiply by 1.5) but what if you’re trying to convert from a 1-inch sensor or a larger-than-full-frame medium format 6×9 camera? What if you really let your freak flag fly and shoot APS-H? The point is that it’s not always easy to determine the crop factor and mmCalc understands this so they made it simple.
Using mmCalc is as easy as plugging in a few numbers and getting the desired result. Simply select your sensor size, enter the focal length of the lens you’ll be using or is attached to the camera, and select the maximum aperture of the lens, and you’re set! Clicking the “Calculate Crop Factor” button will generate the information you need along with an explanation of how mmCalc calculated the crop factor as well as how the conversion of depth of field is calculated and affected.
mmCalc is a fun tool for the beginner photographer and an asset for the more advance photographer trying to explain crop factors in a simple way. If you’re looking for a fun way to kill some time or if you’re looking for an easy to digest primer on crop factors, check out the mmCalc Crop Factor Calculator.