The same lens produces different results on cameras with different sized sensors. As a result, it can be tough to crossshop Micro FourThirds, APSC, Full Frame, and Medium Format cameras.

Crop Factor is a conversion that makes it simple to determine the exact results you'll get with any given lens, regardless of your camera's sensor size. By multiplying your camera's crop factor by a lens' focal length AND aperture, you can determine the fullframe equivalent angle of view, depthoffield (background blur) and a good estimate of the lowlight noise.

Here are common crop factors:

1X: Fullframe cameras like the Nikon D610, D750, D850, D5, Canon 6D, 5D, and 1D, Sony a7, a9, Pentax K1

1.5X: APSC cameras like the Nikon D7200, D5300, D3400, Sony a6500, and Fuji XT3

1.6X: Canon APSC cameras like the Canon 7D, 80D, 77D

2X: Micro fourthirds (M43) cameras like the Panasonic GH5, G9, and Olympus EM1, EM5, and EM10

For more information and to see the previous crop factor and equivalency videos, see http://sdp.io/crop.

To get an outside opinion, here are articles and videos by other people on the same topic:

https://www.dpreview.com/articles/266...
https://petapixel.com/2017/03/29/disp...