This is a first as far as I know. A 35mm F2 lens in Contax RF mount. This lens was made originally in FASTAX mount, a bizarre 1950s bayonet mount for high-speed movie cameras. I took a J-12 in Contax mount that had some marred glass, took the optics module out, bored out the barrel, and cemented in the Raptar. It looks like it covers a full frame, using the through the lens viewer. I set the optics to agree with the RF of a Contax. I do not know of a Fast 35mm lens in Contax mount, although I shimmed a Nikkor 35/2.5 for a friend for his Contax. At F2: This lens renders much like a Canon 35/2 in Leica Mount. F2 Again: F4: Infinity at F4: Not bad for a Junk lens, total of $25 including the J-12. I tried it on the M8, covered the full frame without vignetting. I'll try it on a Contax IIa next. Unlike a J-12, this lens does not extend past the Mount.