Hi! all. i read in my NIkon D5000 on a feature call focal plane position. its used to determine the distance between subject & my camera. it also says the distance between the lens mounting flange & the focal plane is 46.5mm (1.83in) but from these info provided, i still don't understand how i can determine the distance while i'm framing the picture with the view finder. is there something i've overlooked? sorry for the question if it sounds stupid but i'm very new to dslr. hope everyone can understand.