If you love quirky/oddball lenses, the Zenitar 50mm f/2 is something you should check out. It comes in M42 screw mount, but can be used with almost any mounting system through the use of an adapter. And, in true TightCamera tradition, it weighs in at about $50. An added bonus is that it is made in Russia, which folks of a certain age will associate with cold war nostalgia of the 1970s and 1980s.
You’ll have to go full manual on your camera, as this lens has no electronic connections to the body. This one won’t be a hit for action shooting, but it’s fine for portraiture and still life compositions. It’s also very light, making it a nice option for a smaller gear bag that might go on a camping or hiking excursion.
A few stops down from f/2 yields surprisingly sharp images in the center. The edges maintain sharpness at f/4 and higher, and falloff is minimal on a full-frame body (and totally gone on crop sensors).
Build quality is a mix of plastic and metal, and quality control is hit and miss. My copy overall seems to be pretty tight, with the exception of the aperture blades, which appear to be slightly skewed. When stopping down, the 6 blades form an oblong (rather than symmetric) hexagon. This makes for interesting/unique bokeh shapes at f/5.6 and above, but I can’t help but wonder if another copy would have had some kind of unfavorable flaw. I would suggest buying from a retailer that offers a generous return policy, just in case.
It’s pretty hard to beat the Zenitar for the price, but the manual focusing and exposure, along with the necessity of having to use an M42 screw mount adapter to attach to a modern SRL may put some people off. Additionally, the 46mm filter thread size is somewhat odd and will require the use of step-up adapters to make sharing filters with other lenses possible. I found the resulting photos to be quite pleasing. I could have had the same general results with more technologically advanced (if not more expensive) lenses, but that smooth bokeh with interestingly oblong artifacts is difficult to replicate.