Strange light marks on negatives

[lassethomas]

I'm trying out my new 4x10 for my 45H-1 and has come across some artifacts on my negatives that I can't explain
There are areas of light exposure that goes parallel to the long side of the film holder perhaps 5 mm in from the border.

https://scatteredlightblog.files.wordpress.com/2021/04/sheet0305.jpg

https://scatteredlightblog.files.wordpress.com/2021/04/sheet0307-1.jpg


Camera is Chamonix 45-H1 with 4x10 back and chamonix film holder and Fujinon 125mm SW
Of each subject I did two exposures and the artifacts are identical of both. To me this rules out light leaks in the holder or when loading and unloading film or holder.
The two exposures were also were developed separately, ruling out the development process as the culprit.
Film is cut up 8x10 Fomapan 100

So it has to be something happening in the camera I guess. Bellow, internal reflections.
Thing is that two other subjects from the same day was unaffected.

Anyone seen anything like it or has som idea or suggestion?

[ic-racer]

Is the 4x10 bellows secured down here?
214918

[Eric Woodbury]

A straight line. Makes me wonder if you are getting a reflection from the camera back just before the film. With that straight line, it is something close to the film. Some edge in there. You may need to put a baffle in front or add some flocking. A lens shade would help, but I find them a hassle, even tho I know their benefits.

[lassethomas]

A straight line. Makes me wonder if you are getting a reflection from the camera back just before the film. With that straight line, it is something close to the film. Some edge in there. You may need to put a baffle in front or add some flocking. A lens shade would help, but I find them a hassle, even tho I know their benefits.

That's a good line of reasoning. The edge being that straight and sharp it has to be close to the film to be "in focus". Everything is painted matted black inside, but I guess reflections can still happen



Is the 4x10 bellows secured down here?
214918

I'll have a look tomorrow and double check

[robphoto]

That's a very common defect to show in a negative, and I think the advice to check for reflections from the frame around the back of the camera is correct. The solutions as well: minimize the reflectivity of the frame near the back of the camera, and shade the lens as close to the edge of the view area as you can. I often see this when there's something bright just outside the view, like a lightbulb just out of frame, or in this case, a bright sky.