Compiled by Q.-Tuan Luong for
the Large Format Page
Some photographers (like me) are plagued by these problems, which
are among the worse frustrations of LF. Some have never experienced them.
There are zillions of different sources of light leaks.
Holder: Leaks at light trap for dark slide. Leaks because its
warped. Leaks from defective dark slide or dark slide doesn't fit.
Leak at loading flap.
Camera back: Leaks because its warped. Because the light trap keeps
the holder from seating properly. Leaks because something else keeps
the holder from seating.
Camera body: Leaks from cracks or bad joints. Possible around screws
or rivets holding parts on. Leaks from ill fitting lens boards.
Leaks from holes in lens board.
Bellows: Pin holes at corners or elswhere. Doesn't fit at ends
where its fastened to camera body and front.
Leaks from shutters sticking open, perhaps only a pin hole opening.
Can also be caused by defective shutter leaves. Check both cocked and
after tripping. Some shutters have hard rubber leaves and can have pin
holes in them.
Reflective something inside camera. Light outside of the image area
being reflected onto the film.
Film is getting fogged somewhare other than in the camera.
A few diagnosis remarks
fogging extends past the borders from the rails in the holder it has
to be coming from elsewhere than from the camera.
If many negatives have identical an
identical or nearly identical fog pattern it may come from a leak in
the film box. Richard Knoppow
Pinhole leaks would be more likely to look like
superimposed images than oblong blobs. Paul Butzi
If the "light leaks" do not have sharp edges but they do
have edges, i. e. there is not a bright area which gradually fades
must be not too far from the film.
If the leak were in the bellows or in the front board
then I would expect the bright areas to have foggy edges.
Leaking film holders
Check the condition of the hinges on the loading flap. If they are
worn that could be your leak. Is the slide seating all the way down
into the holder? Maybe you have a small hairline crack at the seam of
the flap possibly?
One place they leak is the place where you pull out the
dark slide. Ever take a holder apart? A friend and I did when we
where building a vacumn 4x5 film holder for our astrogrpah (that's
another story). Inside the "top" of the holder, behind the metal
part, is a peice of light brass - it looks like a curved comb. over
top of this metal is a peice of black felt. What happens over tiem is
the felt wears down, "teeth" on the comb loose thier spring and fail
to hold up the felt in place, or break all together. Normally when
you pull back a darkslide, the curved part of the "comb" springs back
up into place, blocking off light. Older holders, the felt may have
holes in it, allowing small light leaks to escape through. Also, the
felt may be very dirty, so no matter how clean the rest of the holder
is, you continually get scratches and dust marks on your flim, carried
in off the felt onto the emulsion of your film from the darkslide
being pushed in. Joseph O'Neil
check these with a flash light by folding down the loading flap so you
can look straight into the holder and shining the light right into the
slot for the slide. Richard Knoppow
Marking holders for identification
If large format users would use a notch-encoding scheme to number
their holders, it would be MUCH easier to exactly pinpoint a leaky
holder. I (and several other large format people I'm friends with)
take miniature files and notch the flap with the files. For me I use
a v-notch for 1-4, square-notch for 5, and a half-round- notch for 10.
Thus, the holder that I've designated to hold sheets 9 and 10 has a
square-notch and 4 v-notches on the 9-side, and a half-round-notch on
the 10 side. Should either side of that holder ever leak, it'll be
really obvious as to which holder (and side) is the culprit. NOTE:
the notch goes into the side that contacts the film, since light hits
the ends of the holder at an angle, there is no need to notch both
sides of the flap. Be sure to clean off the residue with an X-acto
knife and clean the plastic dust out of the holder when you're done.
To identify leaking holders among a large set
The best that we came up with was to load them with the cheapest
paper that you can get (pre cut to 4x5 will save time) and take them
out into the sun and twist each one so that all surfaces face the sun
(remember paper is a lot
slower than film therefore keep them in the sunlight about 5 times longer
Advnatage: you can load them under a safelight.
If you are really cheap and can spend the time, you can use the same
sheet of paper for more than one holder to narrow in on faulty
ones. [Algorithm to determine the minimum number of light sensitive
sheets to identify all leaky holders left as an exercise for the
reader] Don't forget to number all holders (and matching sheets of
paper before you start). Sandor
How to find a leak
I would take the camera into a darkened room and remove
the lens board. I would shine a light into the camera body to see if
there is a light leak in the bellows or the back. If no light can be
seen, put the lens board back on and take the back off and shine the
light in from that end and inspect for leaks in that direction. More
than likely, you will find the leak and patch it with black tape and be
back on the road in no time. Lee Carmichael
Just to suggest another, more definitive, way of finding those
pesky pinhole leaks: if you are in a university and have access
to a photomultiplier tube (try a physics lab), I would give that
a try using an ordinary flash inside the bellows. This way you
can look at a meter rather than trust your eyes to find even the
smallest pinhole light leak.JohnK
Flare problem due to excessive coverage
Another cause of this sort of problem is flare due to the sun or another
bright light source out of the composed frame, bouncing light off the
bellows and dumping the non-image light on part of the film. Since the
lens reverses the image position on film, the upper right of your photo
would be lower left on the ground glass - the sun, outside the frame to
the upper right could be reflected by the bellows to the lower left area
of the GG/film causing fogging. The solution is to use a lens hood,
compendium bellows, or a card to prevent sources outside the composed
frame from illuminating the lens and reflecting off the interior
of the bellows. Michael Gudzinowicz
Finally, as a reward for those who slogged thru all of that, I have
one last note - this I discovered today. A friend had an image
spoiled by what looked like a light leak - the fogging appeared
as a splash of light from the top of the frame. We examined
the negative, and it seemed that, perhaps, it was caused by
the image of the sun, which was just barely out of the frame.
It looked rather as if the image of the sun fell on the beveled
edge of the readyload film holder - around the frame, the bevel
slopes *in* toward the film. And it looked to me like the image
of the sun fell on this bevel, and reflected off and was splashed
across the film. Ick. I think the moral of the story is that if
the sun is just outside the frame, use a lens hood and adjust it
very carefully. Paul Butzi.
Holder not sitting light-tight against camera
I suggest this: once you insert the holder, try wrapping the darkcloth
around it and the back, leaving just enough to pull the slide. Or
maybe wrap the entire back and holder, clip it shut with clothespins,
and pull the slide inside there. It sounds like the holder is not
seating light-tight against the camera. I think it's occasional
possibly due to moisture changes in the atmosphere causing the wood to
warp slightly. David Meiland
Would it be possible to put some black felt where the cutfilm holder
rests against the back? Robert Peters
I had a problem with light leaks when I first started in 4 x 5. Do not take
the dark slide out until you are ready to shoot. Replace it immediately after
you shoot. I ran into my light leak problem by putting just the corner of the
dark slide in first. You have to put the slide in perfectly straight, or you
get a light leak. Rob
I have old wooden film holders that have been a great deal of trouble with light
leaks for the two years or so that I've been trying to use them. I just came
back from a trip and this time I kept the dark cloth on the camera during
exposures and guess what? No light leaks on any of the film, a first!
I thought that the leaks had ocurred in handling the film holders or even
carrying them around, but this seems to indicate that the leaks ocurr only when
opening and closing the dark slides. Frank Kolwicz
that come to mind are: not getting the holder seated before
pulling the dark slide, shifting the holder when pulling the dark
slide. Basically anything that might pull the holder away from
the camera back. If you routinely shoot straight up, are those
more likely to be fogged? The weight of the holder might be pulling
it away from the back due to weakened springs. Paul Butzi
Leaking preloaded film systems
Many people have reported problems with light leaks using preloaded
systems, especially the kodak readyloads and/or polaroid back. Look at
the diagnosis and tips to avoid
Leaks outside of the camera
How and where do you load
your holders? Do you wear, perhaps, a wristwatch with a luminescent
face? (Yes, I *have* fogged film that way). Paul Butzi
If the fogging happens on the unexposed-but-processed film, try a different
lab. If it still shows up, I'd say you're handling it wrong and you'll have
to look at your environment (Don Nelson's point about fluorescents
being able to fog film after being turned off
is correct, in my experience). Pete Bergstrom
1) is the box you transport your exposed negative to the film lab in
2) Are you sure these "blobs" are not processing failures of some kind.
I had a roll of 35mm E6 butchered on me last year by a "professional" lab,
and some of your blobs look a little like what I had on my roll of film.
Either that, or could there be light leaks in the lab somewhere ?