Flare or light leak problem

[Mills]

Hi,

I have been having a flare problem with one specific lens and am struggling to figure out where it is coming from. Any thoughts or suggestions would be greatly appreciated.

It ranges from really severe as in the posted black and white to barely there as in the posted provia image. Maybe 25% of the time its almost invisible or not there at all. The film is developed by a lab so its definately an issue while taking the picture as they get a box of film from a variety of lenses and the artifact only appears on the wide angle shots.

It happens with all my film holders with my schneider 75mm lens and no other lenses. It seems to happen with or without a square filter holder attached and seems to happen regardless of shading the lens with a darkslide while taking the shot.

I have tried a light inside and outside the bellows in a dark room to look for leaks and dont see any, and I have tried covering anything on the camera that is even sort of reflective with no luck.

It is on a recessed board on an intrepid camera that has a minimal focal length of 75mm. Is it possible the issue comes from lack of correct belows extension for the lens somehow? The lens is in beautiful condition cosmetically and if it was a glass issue I wouldn't have thought I'd get clean, focused images occasionally.

Thanks for reading and for any suggestions. Please forgive the cel phone quality image of the film. I didnt want to spend a ton of time getting a nice scan of what is basically garbage.

[Doremus Scudder]

Since it only happens with one lens, the first place to check would be the lens mount, the lensboard and the way the lensboard mounts to the camera. One of these likely is the culprit. The next thing to check is bellows/camera back when the lens is mounted and focused, i.e., when the bellows are squeezed together to get the lens to focus. The compressing of the bellows might cause something to separate that shouldn't. Check those and report back and we'll see what else we can come up with.

Best,

Doremus

[Mills]

Thanks for the reply.

My first thought was the lens mounting to the board, but I double checked that yesterday and cant see any light coming through even as I move the front standard.

I also re-tried the bellows at minimum and maximum extension as well as with the lens focused and still don't see any obvious leak.

Thanks again for taking the time to read and reply!

[Maris Rusis]

Since the flare or light leak doesn't intrude on the rebate edges of the film it must be a in-camera problem. Two ways I've got results like this is in the past:

Failing to insert the film holder properly into the camera and have it seated securely ...or
Opening the camera back momentarily when pulling the dark slide or putting it back in.

Now I firmly pinch all four corners of the camera back to test that the film holder is set correctly ... and
Grip together the camera back plus film holder (the "claw" hold) to make sure nothing moves when pulling the dark slide or putting it back in.

[Mills]

Thanks for the thoughts. I will definately adopt the pinvh while replacing the dark slide.

Looking at it more Im thinking its related to a leak i am not finding and the round recessed lens board reflecting it since there is such a prominant round portion to the flare.


I taped the front standard where the bellows is glued inside and out and will try a test shot this morning. If that doesnt work i might just leave the lens cap on and leave the dark slide out. Rule out an issue from the lens itself and be sure theres a leak i just cant find.

[Kevin Crisp]

Long shot....but is this one of those shutters with the microscopic screw that sticks out and is supposed to mate with a hole in the lens board? The lens isn't really flat if you leave the screw in place and don't have a matching hole in the lens board.

[Mills]

I hadn't heard of that but will check. It looks like a pretty standard copal shutter.

Thanks!

[Kevin Crisp]

Some shutters have them and some don't. I'll bet there are 15 historical threads with people baffled by that little screw preventing them from getting the shutter completely flat on the lens board.

[chris kleihege]

I offer suggestions so rarely because I know so little. Given that, I would check that the lens board is mounting properly to the front standard.

[Mark Sampson]

Whatever the problem is, it will be small. Bigger light leaks will fog the entire sheet of film. So look closely and carefully!