This lens is quite an old and particular lens, designed in the '80s for 6x7 cm film. I've tested on a full frame Canon 5D using a mechanical converter from Pentax 67 to 42x1 and then a ring from 42x1 to EOS. Vignetting is very good, as expected being this lens designed for medium format cameras. Unfortunately the optical quality at full aperture is not perfect, showing noticeable chromatic aberration. It should be stopped down at f/4 or f/4.8 to get best results. Star sizes are not pinpoints, but this is normal being the lens designed for medium format film.