It's fun to play with some older weird lenses,

There are lots of strange lenses out there which can easily be adapted to the Sony mirrorless line of cameras with cheap dumb adapters. Here is what looks like a projection lens with an M-42 mount. It doesn't have an iris but, I shoot with these strange lenses wide open anyway to make the most of their optical imperfections.

https://www.ebay.com/itm/F1-7-FAST-8...53.m2749.l2649

The description of the lens is pretty difficult to follow since it appears to be written in Chinglish However, for $40 USD with shipping, it might be fun to play with. I do like my Russian Helios 58mm f/2 and may enjoy playing with this piece of glass.

Being a alternate to the 75mm f.1.5 Biotar is a dream though and anyone purchasing a $40 USD lens with expectations that it will perform like a lens that presently runs over a thousand dollars used, is bound to be disappointed.

The Sony focus peaking makes focusing a manual focus lens a breeze. In fact I will normally use my adapted Canon EF 85mm f/1.8 lens on my A6500 in manual mode...