The Meopta Meostigmat 35mm f/1.3 is an extreme fast projection lens.
No filter mount, no aperture and no helicoid. This lens was used in 16mm film projectors with 52.5mm mount (Meopta Meoclub 16).
It can be used with modern DSLMs after modification (cutting the lens barrel), but can only cover APS-C sensors or smaler. Use without modification, but with restrictions, is also possible on DSLRs. Because of the very short flange focal distance of this lens it´s not possible to focus to infinity with DSLRs.
This lens is ideal for cameras with a short flange focal distance (for example the Sony E-mount system or Canon EOS-M) and artistic photography.