Try the Asahi Pentax Takumar 50mm f/1.4, m42 mount plus cheap adapter, less than $100 shipped from ebay.
There's a lens element that's radioactive, as it decays the lens goes yellowish, you can fix it by sticking it in the sun for a few days (UV fixes it, a UV tube would be better). Or just leave it a bit yellowish. Best colours and contrast of any of my lenses (past f/2, f/1.4 is a bit washy and there's no stop in between). Sharpness @ f/2 beats my niftyfifty @ f/4 too.
A radioactive lens? Just what are they doing with it O.O
I'd assume you'd need to take off your UV filter when you leave it out though?
I love the contrast on my 135. Then again its the main prime I use, but thats just me I guess...
Apparently lens coating wasn't very advanced back then and they had to use thorium, a radioactive element to coat the lens.
I was in a tight budget (teenager here
) and I wanted a fast 50mm lens. I already own MF lenses so I didn't mind getting a film era lens, stumbled across the Nikkor 50/1.4 and the Takumar, ultimately ended up with the latter because of the beautiful golden tint, caused by the decay of Thorium.
For half the price and sharper results than the EF counterpart, I have zero complaints on this lens.