The ABC of Photography – Crop factor
Sensors of several different sizes are used in D-SLRs, and this size affects the angle of view offered by a particular lens. The smaller the sensor, the narrower the angle of view. The ‘crop factor’ is to convert the actual focal length of a lens to the effective focal length (EFL – see below). The crop factor for Four Thirds and Micro Four Thirds models is 2x; the crop factor for most popular D-SLRs is 1.5x or 1.6x. Full-frame D-SLRs need no focal length conversion, so they have a crop factor of 1x.
Sources: Pixabay, Wikipedia, Susan Wingfield Lamar High School