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[OM] OM40 light leak

Subject: [OM] OM40 light leak
From: mike blayney <mikeblayney@xxxxxxxxx>
Date: Wed, 15 Nov 2000 02:10:41 -0800 (PST)
I have conducted some tests on my OM40 for light leaks and these are my, as
yet, not entirely definitive conclusions. They may be of help to others. Rather
a long post, so hit delete now if not interested.

First the symptons (all also present on the negatives):

1. A red/pink fogging, always on the left of the print. Soft blurred effect
(i.e. no hard edges to fogging). Sometimes just observable, sometimes ruinous.
2. Strongest at the edge although not always entirely to the edge.
3. Sometimes uniform top to bottom, sometimes more at the bottom or top.
4. Very erratic, only occurs about 1 in 30 shots.
5. Always during bright sulight.
6. Fogging is within the 35mm frame.

Lots of help from the list which suggested:

1. Shutter dragging and other shutter defects.
2. Film window on the back of the camera.
3. The LED battery warning window on the front of the camera.

Had the shutter checked at my helpful local camera shop. It's OK. Very slight
"wedging" (if I understand it correctly, uneven exposure across film) - would
not be visually detectable. No pinholes etc. So, ruled out 1.

Always have body half of never ready case on, so ruled 2 for now (although will
need to check).

I then spent some time in a dark room with a torch and a piece of transulent
plastic where the film would be. Could not detect ANY light when shining the
torch into the various camera orifices. Interesting in view of subsequent
tests! There were, however, reflections off the stop tab for the fresnel device
(which sits behind the mirror) and off the tab on the fresnel device which
rests on the stop tab. Both these appeared to be bare metal. These were treated
very carefully with matt black enamel. Whether this has had any effect is not
known but clearly it is a potential source of flare.

With a film in, the camera was placed facing the early morning sun shining into
my sitting room for 5 minutes with lens (no cap) in place. It was wriggled for
2 of these minutes and static for 3. The shutter was then fired in manual at
1/1000th with lens cap on and in deep shade. Film wound on. lens removed and
wriggled facing the sun for 1 minute followed as before with a blank 1/1000th
shot.

The results were dramatic and distressing. The first showed extensive fogging
mainly towards the left hand side with a couple of pointish highlights. The
overall effect was blurred and soft. There also appeared to be two faint
vertical white (on print) streaks on the preceding (normal picture) shot.
Fogging was confined to within the picture frame as far as could be judged. The
second  showed very strong, vertical and slightly arced streaks about third in
from the left. These extended beyond the frame top and bottom. Fogging on the
remainder of the negative was not as strong as the first.

Now, I don't go around pointing the lens at the sun all the time but it's
impossible not to do so occasionally when shooting and the effects above would
clearly produce foggong in these circumstances. Neither do I change lenses into
the sun although again it's not possible to occasionally let this happen.

One evening (no sun!) I conducted further more selective tests pointing a T32
flash at orifices. I should have thought this through - although a flash is
bright, there is a very small quantity of light, far too small for an effective
test. All test negatives were clear.

Clearly there's a serious leak within the mirror box (could be the LED but then
the second test shouldn't have changed the fogging). Now I could do more tests
but the camera is under warranty from a dealer so IT'S GOING BACK. Either they
fix it or, as my confidence in the OM40 is waning rapidly, I try and do a deal
for another body  (Thinks with a gleam in his eye -  "The budget might stretch
to an OM2S so maybe I can come out of this on top and with a better body - at
least a camera body, the other one's falling to bits").

I  realize now that I must be under the influence of Zuikolism as despite all
these problems I don't want to part with the camera (it leaks like a
sieve!!!!!!!!!!!!!!!). The thought of the next few days without a shutter
button to press is already creating mild panic and withdrawal symptons. Oh well
one more "ism" to add to the others. I'm sure with the help of the list and
"one day at a time" I'll get through it.

Mike Blayney, Devon, UK 


=====
Mike Blayney, Devon, UK.

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