[LargeFormat] Light Leaks around Lens Boards

[Richard Knoppow]

    Recently I aquired a Packard flash synch shutter mounted
on a 6x6 inch lensboard of the type used on several cameras.
My intention was to use it on my Agfa/Ansco 8x10 Universal
View camera. I have a military  model, which has a 6x6
lensboard rather than the larger ones used on standard Agfa
cameras of the time. The air gland for the shutter was
mounted at the bottom edge of the lensboard, a common
location for it. What I discovered is that it would not fit
the camera. The reason was that my camera had an additional
built-up section inside the front window of the lens board
opening. This conssited of four pieces of wood about 3/16ths
square and covered with thin velvet. A very effective light
trap but not original Since it was not glued in and could be
replaced, I removed it. I found that the lensboard with
shutter fitted fine. From photos of other similar cameras
its obvious that the extra section was an add-on. I found
out why. There is a slight light leak around the edges of
the lensboard. Mostly at the sides since the metal strips
which hold the lensboard at top and bottom block any light
from entering there. The leak is slight but present.
  I then checked my 5x7 Agfa/Ansco Universal view camera and
it turns out to have the same slight leak. I had never been
aware of it before.
  I may replace the light trap in the 8x10 but I am going to
try a simple felt trap first because it will allow clearance
of the lensboard with Packard shutter. I will also try the
same thing on the 5x7 camera.
  Since several other makes of cameras have very similar
arrangements for the lensboard it may be worth seeing if
they have a similar leak. Cameras like the Kodak 2D and
Burke & James cameras are similar although I am not sure
they don't have more light trapping than the Agfa/Ansco
which has simply a stepped hole for the board to fit into.
since my other view cameras are much newer Calumets I can't
compare them. The 8x10 Calumet has a felt gasket.
  I tested for the leak by taking the back off the camera
and shining a flashlight around the front of the lens board
while looking at it from the back. I suggest others with
similar cameras do the same. I would be interested in
hearing from others who discover similiar problems. Also, if
you have a Kodak 2D or other camera, does it have any
further light trapping in it.

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Richard Knoppow
Los Angeles, CA, USA
dickburk@ix.netcom.com