Lisco Film Holder Light Leak

[alanmcd]

I have some Lisco Mark II 4x5 film holders. They are in very good condition, just looking at them. But I've noticed an exposure problem on the notch side of the film. I thought initially it could be the developling since the film is notch side up in my mod54 in the tank and may not be covered by developer or something. But I can now see a light leak of tiny pin holes when I open the flap of the holder. The tiny holes are in the tape which creates the hinge for the flap. So the light is leaking from the time I pull the holders out of my tent. Obviously not much happens in the fridge so I suppose it mostly happens when I pull the holder out or my camera bag, load the holder and wait for the frame. the presence of the dark slide or not makes no difference since the light is coming in through the mitre of the flap and therefore under the dark slide anyway.

Has anyone had this issue? and fixed it by pulling what looks like a very good taping job off the holder and replacing with trusty old black fibre tape? Will my tape be good enough?
If I tape over the existing tape, I'm concerned the extra thickness of the tape will cause the film to be higher on the hinge side, or maybe even create a tapered leak down the long side of the holder while it rests on the camera.
Alan

[vinny]

The tape only holds the hinge on. It doesn't need to be opaque to work properly.

[Jim C.]

I've never had such a issue yet with my various holders, the pin holes in the tape hinge might not be the culprit,
the end flap has a built in light trap so if the end flap is warped or has grit that may be preventing the
flap to close flush those pin holes could cause a light leak.

The tape sits in a recess so over taping it is probably not a great idea since as you said it could lift the holder
on that end and create more problems, best to remove and replace.

[alanmcd]

I've never had such a issue yet with my various holders, the pin holes in the tape hinge might not be the culprit,
the end flap has a built in light trap so if the end flap is warped or has grit that may be preventing the
flap to close flush those pin holes could cause a light leak.

The tape sits in a recess so over taping it is probably not a great idea since as you said it could lift the holder
on that end and create more problems, best to remove and replace.

OK - that might rule that out.
Actually I see the unexposed edge of the film is not exposed at all. This would have to be exposed if my theory were correct.
So it must be something else.
I'll try developing with the notches down in the tank
Alan

[LabRat]

Like Jim said, the hinge material usually sits in the recess… But there is usually a little space there to put some thin tape over the material… And Vinny's right about that the hinge material can leak a little because most holders have a baffle step light trap there to minimize leakage… But if the end flap can wiggle around with the old hinge material, that can expose leaks…

Most leakage there is from the gaps on the flap ends, that usually get covered when the slide is fully inserted, but sometimes the slides get switched from another holder that can be just a little shorter, and don't extend enough for proper sealing… And check to make sure the flap sits flush when closed… If it sits a little lower than the rest of the holder, you can shim the flap from underneath with thin photo tape to raise it a little...

On wood holders, sometimes the flap shrinks a little, and can open the gap… I apply a drop of superglue there to slightly swell and expand the ends… Check for warpage...

And check to see if the holders might not be sitting flat on the back, or other possible back issues…

Good Luck!!!!


Steve K

[alanmcd]

It's not the lens, it happens on both my 65mm and 180mm lens
It's not the way the holder sits against the back because the lightest part is right up against the unexposed edge of the film and the holder has a lip which would cause a shadow.



But this is typical

Alan

[Jim C.]

I don't see what you're talking about, other than a double set of sheet film numbers ( which is odd to me, I thought holders only had one number wheel )
it looks like a natural progression of light sky to darker water.

[alanmcd]

Maybe this is it... a small gap in the corner of the felt light trap
Alan

[alanmcd]

I don't see what you're talking about, other than a double set of sheet film numbers ( which is odd to me, I thought holders only had one number wheel )
it looks like a natural progression of light sky to darker water.

If you saw a full set, you'd see what I mean. It's actually not, in fact, all the way along the edge, it's always brightest in the corner. There's no gap in the felt at the bottom corner. I'll try to plug it up and see.
Alan

PS. I have 2 number wheels which helps when the background of one is so dark you can't read it. I have 5 holders, so 0-9 is perfect for my logs.

[alanmcd]

I've never had such a issue yet with my various holders, the pin holes in the tape hinge might not be the culprit,
the end flap has a built in light trap so if the end flap is warped or has grit that may be preventing the
flap to close flush those pin holes could cause a light leak.

The tape sits in a recess so over taping it is probably not a great idea since as you said it could lift the holder
on that end and create more problems, best to remove and replace.

Jim,
You say the end flap has a light trap. Mine doesn't have a light trap. It's not even a mason mitre. It's a straight mitre join. So when the flap is closed, and the dark slide is in place, if you cut the hinge with a razor blade, you could microscope a view at the notched film edge inside.
If it had a mason mitre hinge, there wouldn't be a straight line view to the edge of the film.



This is what I have. If light could get past the hinge, it would go straight down the film plane at roughly 45 degrees. It may then get reflected under the dark slide to the edge of the film.
Are your holder the same design?