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.

146925

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]

146926
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.

147029

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?

[alanmcd]

My next attempt to solve this puzzle is that I will place my holders into a black poly bag (at least the hinge end) before I take them out of the change room. I will keep them there and only insert them into the camera when the camera is shrouded in a dark cloth. I'll take the photo and, under the dark cloth, place the holder back into my light trap. I'll only take the holder out of the light trap when I unload them into my MOD54 and tank.
Hopefully I will see at least a minor difference in the overexposed edge.

[ruthbarba]

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

The tape only holds the hinge on.
http://hautavis.net/131/o.png

[alanmcd]

The tape only holds the hinge on.
http://hautavis.net/131/o.png

Correct.
And it has, by nature, pinholes, where the tape filler breaks down over time.
If the hinge was a mason mitre (45deg plus 90deg form) there would be a light trap. But a straight 45deg mitre woudl surely allow light to travel down to the film plane.

[Willie]

Have you tried developing one unexposed sheet of film directly out of the film box? No loading in the holders and no other exposure to any light source?
With all the sheets showing the same problem it is possible the box of film has been exposed to a light source somehow.

[alanmcd]

Have you tried developing one unexposed sheet of film directly out of the film box? No loading in the holders and no other exposure to any light source?
With all the sheets showing the same problem it is possible the box of film has been exposed to a light source somehow.

I did think to do that but I had already started a new box and it's happening with the second box. Exactly the same so it's unlikely to be the film.

[Jim C.]

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.

147029

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?

That 45 deg edge is part of your light trap, if your film is seated properly in the holder, the 45 deg portion of the flap
and the flat that has the number wheels should be flat against the septum of the holder, light is not going to bend past those two angles.

If you did razor the tape and you were to see the edge of the film thru a slit that thin then the film is not loaded properly,
either the film or something else is holding the flap up.

I'll have to check my other film newer holders to see if I have any with dual number wheels, I don't recall that they ever had dual number wheels
if they were customized then the extra wheel could be the culprit.

[alanmcd]

I'll have to check my other film newer holders to see if I have any with dual number wheels, I don't recall that they ever had dual number wheels
if they were customized then the extra wheel could be the culprit.

The extra wheel? They're identical wheels at either end of the holder flap. Why would one of them be the culprit?

[alanmcd]

That 45 deg edge is part of your light trap, if your film is seated properly in the holder, the 45 deg portion of the flap
and the flat that has the number wheels should be flat against the septum of the holder, light is not going to bend past those two angles.

If you did razor the tape and you were to see the edge of the film thru a slit that thin then the film is not loaded properly,
either the film or something else is holding the flap up.

You're right. Hard to believe light getting past that. I've also mentioned elsewhere that if light were passing here, the edge of the film would not be black (unexposed). It is black (unexposed). It has to be happening during exposure of the film. I've sort of ruled out development (strange convection in the tank), I filled the tank even higher with the last batch and it made no difference.

[Jim C.]

The extra wheel? They're identical wheels at either end of the holder flap. Why would one of them be the culprit?

Like I said, I have similar holders that you mentioned in a development issue thread, I only recall there being one in the button lock holders.
I've been shooting 5x7 and 8x10 lately and have to take a look at the 4x5 button lock holders I have to see if there are two number wheels in them.
If there is only one then the second may have been custom installed, it could be the center pin on the wheel is too tall and is holding that end of the flap
up or the flap is warped from the installation.

[alanmcd]

Like I said, I have similar holders that you mentioned in a development issue thread, I only recall there being one in the button lock holders.
I've been shooting 5x7 and 8x10 lately and have to take a look at the 4x5 button lock holders I have to see if there are two number wheels in them.
If there is only one then the second may have been custom installed, it could be the center pin on the wheel is too tall and is holding that end of the flap
up or the flap is warped from the installation.

No - these aren't custom installs. They are manufactured plastic. Fully molded with index wheel notches. The spindle is below the flap surface. Everything sits perfectly.

[alanmcd]

Like I said, I have similar holders that you mentioned in a development issue thread, I only recall there being one in the button lock holders.
I've been shooting 5x7 and 8x10 lately and have to take a look at the 4x5 button lock holders I have to see if there are two number wheels in them.
If there is only one then the second may have been custom installed, it could be the center pin on the wheel is too tall and is holding that end of the flap
up or the flap is warped from the installation.

What about this theory: Since the edge of the film under the flap remains covered and unexposed, it is black. This suggest that the overexposure is occurring during normal exposure and not while I carry the holder around with me. The overexposure is pronounced in the negs where the index wheel corresponds with a position in the sky (above horizon) where the most light is obviously falling.
Could the light during exposure, falling on the transparent index wheel plastic, be subject to magnification and or reflection across the negative at this spot? causing the overexposure? As if the wheel become a little bright light under normal aperture opening...

[Fred L]

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.

146925

But this is typical

Alan


can you post more of the film as I can't see anything wrong with this cropped photo.

[alanmcd]

can you post more of the film as I can't see anything wrong with this cropped photo.

Sure - I placed them in the other post but here are 3 raw scans
147083

147084

147085

they're typical

[Jim C.]

What about this theory: Since the edge of the film under the flap remains covered and unexposed, it is black. This suggest that the overexposure is occurring during normal exposure and not while I carry the holder around with me. The overexposure is pronounced in the negs where the index wheel corresponds with a position in the sky (above horizon) where the most light is obviously falling.
Could the light during exposure, falling on the transparent index wheel plastic, be subject to magnification and or reflection across the negative at this spot? causing the overexposure? As if the wheel become a little bright light under normal aperture opening...

I checked my holders and they do indeed have dual number wheels, the recess also has an little nub that the notch on the wheel engages
to keep it from spinning freely, I tried setting the wheel so that it doesn't engage that nub to see if it would lift the flap but to my eyes
it seemed not to have any effect.

I highly doubt that those number wheels will act as a light pipe.
You could shoot some sheets that do not have the sky in view, to see if that overexposure occurs.
And/ or ink in the wheel so that it's not clear.

[Doremus Scudder]

Alan,

Just looking at the negatives, I can suspect anything from a developing issue to camera back issues. Since you mention that you've flipped the negatives in the developing process and eliminated that aspect, I'd be looking for light leaks at the camera back, filmholder seat, bellows pinholes, or even simple operator error (pulling the back away from the seat when inserting/removing the filmholder). That said, the more I look at the examples you've posted, the more it looks like uneven development. Do double-check that aspect as well.

Of course, I'm assuming that you can see the areas of increased density on the negative. If not, then scanning or printing problems leap to mind...

Since the rebate of the film is not exposed, it's not a holder issue. I think you can safely eliminate the holders as suspect and look elsewhere.

FWIW, be careful when replacing felt strips to assure that you use the same thickness. Even a fraction of an inch thicker and you can throw off the focus. Don't ask me how I know...

Doremus

[alanmcd]

Alan,

Just looking at the negatives, I can suspect anything from a developing issue to camera back issues. Since you mention that you've flipped the negatives in the developing process and eliminated that aspect, I'd be looking for light leaks at the camera back, filmholder seat, bellows pinholes, or even simple operator error (pulling the back away from the seat when inserting/removing the filmholder). That said, the more I look at the examples you've posted, the more it looks like uneven development. Do double-check that aspect as well.

Of course, I'm assuming that you can see the areas of increased density on the negative. If not, then scanning or printing problems leap to mind...

Since the rebate of the film is not exposed, it's not a holder issue. I think you can safely eliminate the holders as suspect and look elsewhere.

FWIW, be careful when replacing felt strips to assure that you use the same thickness. Even a fraction of an inch thicker and you can throw off the focus. Don't ask me how I know...

Doremus

Correct me if I'm wrong, but if it's a leak at the camera back, then it would take effect as soon as the dark slide is removed. No? If the film is left sitting in the camera with dark slide removed, then the longer it sits, the worse the effect. Same as if it's a bellow issue. But this is independent of the time the film is sitting with dark slide removed.
I can wait ten minutes or no minutes to release the shutter - the effect is the same.
Same if it's film holder seating.
The holders have a little release button. I can remove the correct slide very easily once the holder is seated in the back so there's no jumping of the holder while I struggle to remove the slide.
And again, the effect is the same across all film.
Seems to me that it has to be an effect related to the actual exposure process.

[Cor]

You would be surprised what a weird effect a tiny light leak can do to a film. On my Toyo 810M I had brand new bellows installed, I had to send in the frames to which the bellows attach. I had some mysterious overexposure on one of the short side of my 8*10 negatives, but not always !

After extra careful checking with a flash light in the dark there was a ever so tiny light "line" peaking through the bellow standard, very hard to see. The bellows frame was slightly warped, although the frame fell into a U shaped profile, and everything is matt black. I straightened the frame as good as I could, put a piece of black wire in the U shape profile on the camera, and after inserting the bellows put black cloth tape on top of the frame and U profiel: no more mysterious light peeking through.

Took me a long time to nail it down, first blaming the film..

Good luck,

Cor

Ps do you see the same phenomena with a different holder ?

[Huub]

To be honest: this looks much more like a development issue to me, not a light leak. The fact that it is stretchinng along the complete short side of the negative with density increasing slowly makes my mind wander in that direction. Wth light leaks i would expect much more abrubt changes between dark and light and more randomness as well, with differences between the negatives too. Try developing a few sheets in a tray and see if the effect persists...

[Doremus Scudder]

Okay, I'm leaning toward developing issues more and more. Notice that the problem is in a higher-density area or the negative; precisely the area that would be most affected by increased development (just like developing longer to get more contrast doesn't affect the low and mid tones). I'd do this: expose two negatives of a similar scene with bright sky in that offending corner and a dark foreground below it. Then, develop them both in your Mod54 but with one notches up and another notches down. If the problem is reversed on the one with the notches in the not-usual orientation, then you've got a development problem. If not, then post again and we'll take it from there.

Another thing that occurs to me is internal reflections. Usually you see this as a definite line just inside the image area on a negative, but do check your camera and holders for any smooth or shiny surface that might be reflecting light. I have a reflection problem with some holders from time to time and have to sand down the smooth surfaces to remedy the situation.

Good luck, these problems can be hard to track down.

Doremus

[alanmcd]

Thanks everyone for your assistance. I have now ruled out all hardware issues. It's not the camera. It's not the holders. It is definitely development. It's a matter of over development of highlights. I now have a plan to address it.
Alan