The legendary Helios 44-2 mounted on a Pentax Spotmatic. Swipe to the right for a photo taken with this Helios and Sony a7.
I borrowed this lens from a friend to experiment with it. Wide open the rendering is really characteristic. The swirly bokeh is caused by field curvature and mechanical vignetting. The lens also flares like hell and loses contrast when there is a bright source in (and outside😅) the frame, so you have to use that for creative purposes. One thing I observed, is that the lens is way better corrected for axial chromatic aberration than the fast 50mm lenses from the 70s or 80s.