View Full Version : Lens problem?

A. Mouton
16-Nov-2001, 00:47
A friend of mine bought a used Fuji SWD 5,6 / 90mm lens ( serial n? 570...) and mounted it on either a Sinar F1 or an Arca Discovery. The images made with the t wo cameras at f:22 and infinity are sharp on the 4/5 part of the film but are un sharp along a linear vertical strip at the left side. This problem can be seen o n the ground glass of both cameras, so I do not think it comes from the camera i tself nor from the fidelity holders ( the Arca is new and so the Fidelity's). Co uld this problem come from the lens? There is no washer between the two parts of the lens but the front part of the lens is mounted on the lensboard with two th in washers in between. Is it a proper way of mounting this lens? Can someone exp lain?

16-Nov-2001, 03:35
Have you tried rotating the lens to see if the problem rotates with it?

John H. Henderson
19-Nov-2001, 07:45
That's bizarre.

I was going to suggest that it is the film holder, but since you see it on the ground glass, that rules that out.

That seems to be kind of a weird problem for a lens.

I'm not familiar with the Fujis. Do they have a little anti-rotation mounting screw on the mounting surface of the front element like my Schneider has? This screw is meant to go through a small hole in the lens board to keep the lens from rotating. Many people just take it out. If you have a screw like that sandwiched between the front element and lens board, your lens axis might not be normal to the film plane.

Go in a dark room, but a light bulb in the back, and see if any light is leaking around the lens/lens board interface.

Are you able to adjust focus and get a sharp image along the normally fuzzy part?

I think using two different camera would rule this out, too, but are you sure that everything is zeroed correctly? Sounds like you might have a tiny bit of lens swing.