The focal length of the lens never changes. A 50mm lens is a 50mm lens regardless of sensor size. The D1 and D2 series bodies have DX sensors. Since the DX sensor is smaller than a "full frame" (FX) sensor, a 50mm lens on the D1 will have the Equivalent Field of View as a 75mm lens on an FX or 35mm Film body. Good Luck and Enjoy your Nikons!