Light leak on a custom built 4x5 with a Schneider 47mm lens.

[Timhop]

Hi fellow 4x5 enthusiasts.

I have a question regarding a 4x5 camera I bought from an old Belgian guy living here in South Africa. After running a film through it I noticed a light leak on each neg, in the same place (I’m using a Horseman 6x12 back on it). After noticing a missing screw at the base of the lens was letting a sliver of light in, I replaced this screw thinking I’d fixed it. But after putting another roll through, it’s still there.

The previous owner had painted the inside all black with silicon, but some of this silicone around the base of the lens has come off, leaving two or three shiny screws exposed. Could this be causing some reflection of the light reflecting in turn off the surface of the film? I’m hoping someone can help me solve this? I’m thinking that because the lens is so wide and sits so close to the film plane, this could be the case. Am I barking up the wrong tree?

Kind regards to all
Tim
221528

[trog]

Can you post a sample negative?

[Timhop]

Can you post a sample negative?
Here is one sample, from my other back, a Graphlex 6x8.
221552

Here is a shot where you can see the shiny screws

221554

[Oslolens]

More pictures of the film, please. And make sure to negate the pictures.
Are the light leaks depending on the time the dark slides are open?
Are they depending on the sun position?
Have you checked the shutter for light leaks through the lens both before and after exposure?

Sent fra min SM-G975F via Tapatalk

[Timhop]

The leaks don’t seem dependent on the time the dark slide is out, as they all seem to be of a similar density on the neg.Thanks for the tip regarding sun position. I will try to ascertain this. I have painted the screws black to eliminate that possibility.

Are the light leaks depending on the time the dark slides are open? More pictures of the film, please. And make sure to negate the pictures.
Are they depending on the sun position?
Have you checked the shutter for light leaks through the lens both before and after exposure?

Sent fra min SM-G975F via Tapatalk

[Gary Beasley]

Do the light leak test with a flashlight inside the bellow from both directions. I wouldnt be surprised you find a pinhole.

[Timhop]

Do the light leak test with a flashlight inside the bellow from both directions. I wouldnt be surprised you find a pinhole.
Thanks for the feedback Gary but this camera (because the lens is of such short focal length) has no bellows

[Jeff Keller]

I'm guessing that you haven't been able to see the light leak when looking at the ground glass.

You might try wrapping the whole camera in a dark cloth preventing any light from hitting the camera. That would identify that the light coming through the lens was the cause (or not the cause) of the problem.

[Gary Beasley]

Thanks for the feedback Gary but this camera (because the lens is of such short focal length) has no bellows

It still might be possible to get a light inside it and observe if any opening are present where they shouldnt be.

[Eric Woodbury]

At low angles, most surfaces reflect.

Have you tried flocked paper inside. Used in telescopes to reduce background 'stuff'.