I have it mounted on Spotmatic F. The "infinity" on the lens is at about 10 meters when looking through the viewfinder. I have other M42 lenses mounted on the same camera and they focus to infinity or even slightly past it, but this Super Takumar does not reach the infinity. I was mainly shooting at shorter distances (portrait) in the past with this lens, so I did not notice this issue. And at short distances the focus (on negatives) was accurate, but yesterday I tried to take some landscape pictures and noticed this issue. I did not develop the film yet, so not sure how this will look on the negative, nevertheless - what could be an issue?