Originally posted by UnFstudio I was thinking about Pentax medium format lenses, but the field of view question pops up.
If the lens image circle is made to cover a medium format camera than on super 35mm the crop is going to be even more significant, right?
(Super 35 sensor already gives a crop of 1.7 compare to the full frame, and we are talking medium format lenses)
Yes.
I'm thinking the Pentax lenses made for 35mm full frame will work the best for you.
As for other M42 lenses, the Soviet lenses have some interesting offerings. I have an Industar 61LZ, a 50mm f2.8 thread mount. It does a nice job of rendering, has great bokeh (in the middle of the range it makes 6 pointed stars of highlights), and the aperture ring is clickless. So all it would need is an adapter, and focus and aperture ring mods for cinematography.