8x10 film back light leak

[jvuokko]

Hi,


I have some 8x10 film backs with similar light leaks.
But I can't reliable identify the source. The brightest area seems to be on the film's notched edge, which is far off the dark slide.
Obvious suspect is dark slide's sealings as the it's the side that points towards the bright sky. But how the brightest leaking marks are on the other edge of the film?

[Vaughn]

My first impression is that it might not be the film holder, but the camera back. Try a 'bellows test'. Insert a holder in the camera, remove the lens, and in a completely darkened room, insert a torch (flashlight) into the camera by the way of the front standard. What you will be looking for is any light working its way past the film holder -- especially near the hinge end of the holder.

Once you have either confirmed or eliminated the camera as the problem, then you can take a closer look at your film holders if needed.

Vaughn

[Jody_S]

If it were the film holder's light seal, the light leak would extend all the way to the edge of the film. Your culprit is somewhere else. I've had similar problems when I didn't properly latch my back to all 4 pins, 1 corner was raised a little.

[Jim C.]

I assume they are plastic film holders, are the to halves of the holders ( where the glue seam is ) split ?
It also looks like the film is fogged with something on top of the sheets, a light leak in your changing bag
if you use one ?

[Vaughn]

I think what you are seeing, Jim, is the shadow thrown by the edge of the holder as light sneaks in.

[Daniel Stone]

test your bellows too, I have a feeling you might have a pinhole(or more) somewhere close to the back....

-Dan

[C. D. Keth]

Is the focus on the leaky side any different than it should be, any softer or deeper than you remember setting?

I had a similar leak when a small twig went unnoticed between my holder and the back. It held the holder about 1/16" out from the back and caused a leak that included a shadow of the holder's inner edge, like yours appears to, and it also threw off the focus on that side a little bit. You might also check the holder used for this frame and the inside of your camera back with a straightedge to see if it is warped any.

[jvuokko]

Thank you!

Vaughn was right. The rear end of bellows was not installed properly (my mistake). It fitted tightly, but there was small gap from which light can enter in certain situations. Especially when rear rise was used.

Things that should inspected regurarly but often forgot...

[C. D. Keth]

Glad it was a simple find'n'fix. Sometimes light leaks can really be a bear to find.