Help identifying light leak (images included)

[Rhemz]

Hey guys,

I'll start off by saying i'm very new to large format photography. I've shot digital for about 7 years and decided to give LF a go a few months ago. I assembled a modest setup consisting of a Tachihara 4x5, a Rodenstock 90mm 6.8 & a Schneider 150mm 5.6. I took went on vacation to Cape Cod a few weeks back and took it as an opportunity to spend some serious time getting acquainted with the view camera.

I took 12 exposures (velvia 50) while I was there, and got them developed last week at a local shop. Unfortunately, it appears i've got a serious light-leak somewhere and every exposure came out with similar burn marks. The guy at the shop seemed knowledgeable and said it looked like a leak in the bellows, probably towards the back of the camera; I found that peculiar as the Tachi is new, and i've spent the better part of an hour checking it in my dark room with a flashlight to no avail. I'm using Fidelity Elite and Fidelity Custom film holders, and the burns are of similar shape and location regardless of which holder I used, which makes me think it's not a leak in the holder.

This, combined with the consistent shape/position of the burn mark(s) makes me think the leak may be coming from either
A) where the back attaches to the camera body, or
B) the contact between the film holder and the camera back.
I'm currently leaning towards B, as it's contact between a ridged plastic surface and glossy cherrywood.

I've noticed that while the camera back & body fit snugly and the contact strips are painted matte black, there is one thin strip where it is unpainted. I plan on picking up some black paint today & painting over it just to make sure. As far as the film holder->camera back issue, I was thinking of picking up a sheet of black velvet & gluing it to the camera back as a light-proof buffer between the holder and the glossy wood, but before I started gluing and painting my camera I thought it would be prudent to get some opinions from the seasoned pros (you guys ).

Here are the images:





Following my assumption of B: These are both horizontal images, with the burn marks showing most prominently in the bottom-left of the image, meaning the leak is worst at the top-right of the camera back. I load my holders in from the right (darkslide comes out on the right side).

In this vertical image, the film holder was loaded from the top (darkslide pulled up & out):



I would very much appreciate some expert opinions, as I'm very new to this and don't want to start gluing and painting my camera unduly.

Thanks very much guys. I really hope I can resolve this issue without too much headache -- I thoroughly enjoyed my time with the view camera so far.

-Russ

[pablo batt]

what is your film loading and removal process?

[Rhemz]

The film was loaded & unloaded in complete darkness. It was done in a small, sealed room inside another sealed, windowless room. I don't think the leak was happening at this point. There is a correlation between the intensity of the leak marks and how bright it was when I took each shot.

[pablo batt]

could also be the position of your film holder in the back,

most important to get the film holder located into the small slot on the camera or it will be allowing light to slip in under and at one end of the film holder

[Rhemz]

I just took some shots of the camera back & film holder. Please tell me if I'm loading it improperly:



When the holder is fully inserted, the flat edge of the left side fits snugly against the recessed plane on the left side of the back.

[Mike1234]

Could also be holes in the bellows or at its mounts. Take the camera into a dark room and shine a flashight throught he lensboard opening to look for leaks. Are all of your film holders the modern plastic variety?

EDIT: Or you could have a light leak at the lens board too... or around the lens.

EDIT #2: The shape and location of the fog is a bit perplexing... looks like it's shaded (blocked) on all four sides by the holder. This leads me to assume the leak is at or very near the back of the camera.

[Rhemz]

Could also be holes in the bellows or at its mounts. Take the camera into a dark room and shine a flashight throught he lensboard opening to look for leaks. Are all of your film holders the modern plastic variety?

The bellows have been tested thoroughly & i've found nothing. I've tried with and without lensboards/lenses. Half the film holders are plastic, half are metal. The burn marks are the same regardless.

Also, if it were in fact the bellows or lensboard, I don't think the position of the marks would change along with the orientation of the camera back. Correct me if i'm wrong.

[Mike1234]

Check my edit #2... suspect the leak is at the back of the camera.

EDIT: Check the fitting of the back to the camera.

[Ari]

Mike,
Have you considered your film? Is it possible that you got a bad batch, or that it somehow got partially exposed?
If you haven't already done so, I suggest opening a fresh box of film and trying that.
These things are never pretty.
Good luck.

[Rhemz]

Ari, I had not actually considered that. I'm not sure how likely it is, as the shots were spread out over 2 different boxes of film & the results are the same regardless.


-Russ