Re: fogging on negatives

About this list Date view Thread view Subject view Author view

From: Sandy King (sanking@clemson.edu)
Date: 03/01/03-10:20:35 AM Z


Shannon,

There are dozens of things that can result in fogging. Since the
edges of your film are clear I think it is safe to say that the
fogging is taking place in *the holder when it is in the camera and
the dark slide is removed.* The clear edges suggest that the fogging
is not taking place in the film box, and it is probably not the
result of just carrying the film around outside in the holder. Since
the problem also appears to be happening with more than one holder I
would suggest that the light leak is probably not being caused by a
failure of the light baffle in the holders, since it is highly
unlikely that all of your holders are bad.

The most likely reasons for the fogging, in my opinion, and in
descending order of probability based on your description, are:

1. The film holder is not seating correctly in the camera. The
light-baffle mechanism for most film holders is that there is a ridge
on the holder that drops into a groove on the camera back when the
holder is fully inserted into the camera. If for some reason the
ridge does not drop into the groove there will almost certainly be a
light leak, and it could be anywhere on the film. Check for this by
inserting a film holder in the camera but do not remove the dark
slide. Then, in total darkness, put a light in the camera from the
front and then baffle off the opening. Now look all around the edge
of the back where the film holders meets the back, with very close
attention to leading edge on the right side where the baffle is
located.

2. The back of the camera or of the holder is warped.

3. There is a pinhole somewhere in the bellows. It takes only a very
small pinhole to cause a lot of fog, and sometimes, for example when
the pinhole is close to the crease of the bellows, it will only
manifest itself when the bellows is fully extended, so be sure to
test the bellows for light leaks with the bellows racked out all the
way.

4. Light leak where the frame of the bellows attaches to the camera,
either at front or rear.

5. Light leak where the lens board attaches to the camera, or where
the lens is fitted to the board.

6. Light from the holder itself. The most likely cause is a bad
baffle. To check remove the dark slides and look back up through the
baffle from the bottom of the holder, with the baffle held against a
strong light.

Good luck, but don't leave home again without solving this problem.
There is nothing more frustrating than to fog a lot of large format
film when a short inspection could have detected the problem.

Sandy

>I have been processing some 8x10 negatives that I made in December
>and January on a trip to TN, and a lot of the images have fogging
>around the bottom of the image, the bottom sides I should say.
>Sometimes I think this is caused by the film holder not being seated
>correctly in the camera back, so that the top of it protrudes a
>little. I need to be more careful about that. But, how can I test
>to see if any of the film holders are leaking?
>
>Also, I never seemed to have this problem with the 4x5 camera. The
>8x10 seems to have a tighter spring on the back so that it's harder
>to push the film holder all the way down. Is this just because the
>film holders are heavier so the spring has to be tighter? Also, the
>fogging begins about 1/4" into the image. The very edges of the
>image are ok.
>
>--shannon


About this list Date view Thread view Subject view Author view

This archive was generated by hypermail 2.1.5 : 04/22/03-02:37:24 PM Z CST