REAL WORLD: Put a Xmm lens on your Ymp crop sensor body -- and have the reach -- to achieve [framing] a picture like having a (X * crop factor)mm on your full frame Ymp camera. Both images will having equal framing and image size. Put a Xmm lens on your Ymp crop sensor body -- and have more reach -- to achieve a picture longer/closer/more zoomed in than having the same Xmm lens on your full frame Ymp camera. the crop sensor will have an image with a larger subject while maintaining the same image size. Meaning you would have to physically crop MPs out of the FF image to achieve similar framing.