|
I have pulled apart an old Pentax 67 400 lense which did not quite focus to infinity in the way I expected and had no head room.
I discovered that the lense could be assembled in slightly different ways , depending on the helical thread start, which would achieve slightly different infinity head room and also different near focus.
My thought was that someone had reassembled this lense in error or deliberately to achieve different near focus. It has good infinity focus near the mark now with a little head room after some fiddling. I am sure more modern lenses could not be altered in this way but an old school helical focus lense could have this error.
|