View Full Version : unexplained dark areas on film - any ideas?

Brett Deacon
19-Apr-2005, 23:11
I need some advice on an irritating problem regarding my exposed film. For the second consecutive time I received a batch of slides back from the lab with dark, unexposed areas on the top and bottom of *some* of the slides. To see an example, go to http://www.photo.net/photodb/photo?photo_id=3295174. I am at a loss to explain the source of this problem and I'm hoping someone might be able to offer some insights.

This problem only occurs with images taken with the Schneider 110 XL - not my 75mm or 240mm lenses. It also seems to occur mostly, but not exclusively, on vertical images. The dark areas are always on the very top and bottom - never on the sides - and appear at different places on different images. The dark areas do not show up on the ground glass, at least not when the lens is wide open. There is nothing in front of the lens (e.g., part of the darkcloth, my hand, cable release) that would seem to account for these areas. The shape of the dark areas is inconsistent with the effects of exceeding the lens image circle, and given the huge image circle of the Schneider 110 XL an image circle explanation seems very unlikely. I've been using the same equipment for the past year (including a newer Ebony 45S), as well as the same lab, and this problem developed only recently.

I'd appreciate any ideas about what might be causing this problem and what to do about it. Thanks!

Paul Fitzgerald
20-Apr-2005, 00:20
Hi there,

Is it a new box of film or is it across several boxes? How large is the rear element for that lens? All the obvious answers are too obvious.

Just a thought.

Will Strain
20-Apr-2005, 00:22
It seems to be fairly well defined, which makes me think it's close to the film plane. Could it be something bunching up the bellows?

Eric Leppanen
20-Apr-2005, 01:26
This looks like bellows vignetting to me. The SS110XL has a relatively small rear element, so if the bellows isn't folding properly when compressed it may bunch into the image circle. When focusing with this lens, make sure the bellows is folding properly (rather than collapsing inwards upon itself). I'll bet the problem will then disappear.

Bellows vignetting normally occurs with wide-angle lenses, where the bellows is compressed. I'll bet your 75mm lens has a larger rear element compared to the SS110XL, which more effectively blocks the bellows away from the image circle. That would explain why the 75 doesn't exhibit the problem.

I had this problem with my Ebony RSW45. Due to its fairly thick material the pleats would tend to lose definition when compressed, causing the bellows to fold improperly and bunch into the image area. I mostly experienced this with my SS80XL, but the 45S has a longer bellows so I can understand how it might affect a longer lens.

20-Apr-2005, 05:08
How old are the filmholders. Maybe worth wile a check...

Brett Deacon
20-Apr-2005, 11:07
Will and Eric, I think you guys may be onto something with the bellows. I will check the bellows next time to make sure it is not bunched up. The bellows material is extremely supple and the pleats do tend to lose their definition from time to time. Eric, the fact that you have experienced this before with a similar camera/lens combination makes me think you've hit the nail on the head. Thanks very much for your help!

Kirk Keyes
20-Apr-2005, 13:14
Are you using a bag bellows? It certainly looks like the shadow of the bellows.