If I want to focus with my 75mm lens on my Sinar F, with a DB shutter, the rear stand will almost need to touch the shutter in order to focus (inifnity). You see the rear stand tilt a bit because of the lack of space (with a wide angle bellow ofcourse) and therefor some pictures are partly out of focus. Is this a common problem? I see a lot of the sinaron W 75 lensen mounted in DB boards, so I guess it should work?