Here's some interesting trivia: back in the day, Mamiya built the Nikkorex F for Nikon, and they also built the original Singlex for Ricoh- both with an F mount, weirdly enough. And while the Ricoh Singlex can take Nikon lenses, the Singlex F mount lenses- like this Ricoh Auto Rikenon 55mm f1.4- can't be used directly on a Nikon camera without modification: one of the bayonet lugs is a touch too long to fit. Nevertheless, flange distance is the same as an F, and if you're feeling crafty, it's a pretty simple modification to make. It works on a Singlex too, of course! This lens is in good cosmetic condition, with some paint and finish wear; optics have a touch of dust. Smooth focusing, good diaphragm. A rare one in very good condition.

REMEMBER: this lens will not fit on a Nikon camera or adapter without modification.