Originally Posted by Edensmimi
My husband has a Nikon d40x and a man is trying to sell him a Sigma 70-300MM lens, the man states that it says 70-300mmd on the lens itself, what does MMD mean? Please help I forot to tell you the man has a nikon D1
What he perhaps means is 70-300mm D. The D is for Nikon D mount.
As I pehaps mentioned in an earlier post by you - the focal lengths are 35mm equivalent. Your D40x has an imaging sensor size of 23.7x15mm. So the effective focal length that you will get is 105x450mm (multiply by 1.5 conversion factor)
Also the D lens does not have a focusing motor. The auto focusing is done by the focusing motor on the camera body
WHICH THE D1 has. But the D40x does not have a focusing motor, the auto focusing is achieved by lenses with an inbuilt motor. So the AF-I or AF-S lenses should be used with the D40x for auto focus. The 70-300mm D lens will not auto focus on the D40x