this is actually incorrect. 200mm is equivalent to 200mm no matter what type of camera. you will see people say that 200mm is equivalent to 300mm on a DX, APS-C or crop sensor. that is due to the smaller sensor only being able to capture an image 1.5x smaller than full frame or film. so if you take that same picture with a full frame camera w/200mm lens and crop the picture down 1.5x and then scale the image back to its native resolution, you've basically digitally zoomed in to 300mm.

