Deardorff Light Leak

[pagestudio]

Hello,
I have had a recurring light leak from my 8x10 deardorff. I am attaching an image here. It seems to only be on horizontal frames and I have recently replaced the bellows and still getting the same light leak shape. Any help would be appreciated. I think I need to do a film holder test with paper to see but I have labeled all my holders before and it showed inconsistent results. Lens is Rodenstock 300mm Apo which could theoretically be too much coverage? But it seems to be happening at the holder/darkslide area. It has been a long and frustrating process. Any help would be appreciated.

Thank you,
Page

[sharktooth]

Have you done the flashlight test?

Mount your camera on a tripod, and insert an empty film holder in the back. Do this at night in a dark room. Remove the lens, and reach into the bellows with a small bright flashlight. Looking at the camera from the outside, see if there's any light peeking out from the spring back area, or around the film holder.

[paulbarden]

Do you hold the ground glass frame tight against the camera body when pulling out/replacing the dark slide? People often have issues with light leaks when not clamping firmly on the rear frame when pulling out the dark slide.

[Alan9940]

Another idea to test your holders is to take the camera out on a bright, sunny day and toss the dark cloth over the rear of the camera covering the holder in the camera. Slip under the cloth ensuring no direct light is hitting the light trap side, hold the ground glass frame as suggested above, pull the dark slide, leave it sit for a minute, slip back under replacing the dark slide, again, holding the ground glass frame. The idea here is to not allow any direct light to hit the light trap side of the holder. If you do this, you'll probably want to use paper to minimize the cost so the "open" time might need to be a little longer.

[jim_jm]

Another thing to be aware of is that it's best to insert the darkslide back in the holder squarely, rather than try to insert one corner first. That way the light trap is completely blocked by the leading edge of the darkslide and no light can leak in. If I am able to, I only pull out the darkslide enough to fully expose the sheet, rather than completely remove it from the holder.

[pagestudio]

Thank you everyone! I am going to try the flashlight test this weekend again to see if there are any leaks.

I have not held the spring back tight when removing the dark slide. That could be the problem and it only happens on the horizontals because I somehow pull it towards me. I’m going to start that routine.

I did shoot a few horizontals yesterday since posting where I kept the dark cloth over the film hold, and no leaks!

I searched for a replacement film back but I guess they are hard to come by these days.

[John Kasaian]

Which brand film holders are you using?
i've had similar problems with a few old Agfas.
Is the problem specific to some of the film holders, or is it with every landscape format shot?
Is the spring back fitting flush into the back?
Has the camera been refinished? Maybe dribbled lacquer is preventing a flush fit.