The same lens produces different results on cameras with different sized sensors. As a result, it can be tough to cross-shop Micro Four-Thirds, APS-C, 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 full-frame equivalent angle of view, depth-of-field (background blur) and a good estimate of the low-light noise. Here are common crop factors: 1X: Full-frame cameras like the Nikon D610, D750, D850, D5, Canon 6D, 5D, and 1D, Sony a7, a9, Pentax K1 1.5X: APS-C cameras like the Nikon D7200, D5300, D3400, Sony a6500, and Fuji X-T3 1.6X: Canon APS-C cameras like the Canon 7D, 80D, 77D 2X: Micro four-thirds (M43) cameras like the Panasonic GH5, G9, and Olympus E-M1, E-M5, and E-M10 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/2666934640/what-is-equivalence-and-why-should-i-care https://petapixel.com/2017/03/29/dispelling-myths-around-depth-field-crop-factor/
