Okay, I tried to research this, but did not find a satisfactory answer....perhaps I was asking the wrong question. I understand about the crop factor of 1.5 when using an FX lens (Nikkor 70-200mm AF VR f2.8 G IF-ED)) on a DX (Nikon D90) body. I realize that the sensors are full frame vs APS frame. So why does the exif data say focal length is 400mm instead of 300mm?