I am attempting to attach a digital SLR to a medical retina fundus camera. The fundus camera will accept the direct mounting of most any Nikon F mount camera body and was designed for the attachment of 35mm film camera backs (no lenses needed as the fundus camera delivers focued light directly to the film). When attaching a digital SLR, the images are what you would expect (around 1.5x magnification due to the smaller CCD size). Is there any sort of Nikon mount focal length reducing lens that would get me closer to 1x images like that of film?