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.
To video
To video