dazedgonebye
Veteran
I'm trying to get infinity focus with a 75mm Super Angulon f5.6 on a gran view hand held camera.
With the helical set to infinity, the camera has an adjustable flange distance of 70-78mm.
I am unable to get infinity with this set up. It looks like the lens must be CLOSER than 70mm for infinity focus.
Removing the helical and just holding the lens, I have to hold it about 10-15mm closer to the focal plane to get any focus at all. Flanged distance of about 55-65mm. This makes no sense to me at all and I am at a complete loss.
Why would a 75mm lens need to be so close to the film plane?
I'm at a complete loss....
With the helical set to infinity, the camera has an adjustable flange distance of 70-78mm.
I am unable to get infinity with this set up. It looks like the lens must be CLOSER than 70mm for infinity focus.
Removing the helical and just holding the lens, I have to hold it about 10-15mm closer to the focal plane to get any focus at all. Flanged distance of about 55-65mm. This makes no sense to me at all and I am at a complete loss.
Why would a 75mm lens need to be so close to the film plane?
I'm at a complete loss....
dazedgonebye
Veteran
Additional information.
I contacted the seller to see if he had any history with this lens. He's telling me that it's possible that he mixed the rear element with one of two other lenses when the shutter was getting a CLA.
He's sending the other elements so I can try to match things up.
I'm thinking that could explain things. Let's hope.
I contacted the seller to see if he had any history with this lens. He's telling me that it's possible that he mixed the rear element with one of two other lenses when the shutter was getting a CLA.
He's sending the other elements so I can try to match things up.
I'm thinking that could explain things. Let's hope.
Al Kaplan
Veteran
The lens to film plane measurement is from the optical center (actually the "rear nodal point") of the lens to the film plane. On a view camera it would be normal practice to mount the lens on a recessed lensboard to bring the lens closer to the film plane and still allow for some swings and tilts.
delft
Established
At the .com- schneider-site, the flange focal distance is given as 82.4 or 84.8 mm, depending on if the lens is multicoated or not. I also see a 'back focal length' mentioned of 51.2 resp. 50.7 mm. This would be the distance between the most rearward part of the lens and the film-plane, according to the diagram at the german site . Hope you get this sorted out.
Dirk
Dirk
john_s
Well-known
You will obviously check that infinity focus is possible when the bit(s) arrive. You should also check the sharpness because who knows what might have happened in the "mix-up"?