Spot patterns on negatives. Film defect?

Laci Toth · Mar 15, 2020

Hi all,

I thought that they were fingerprints when I developed the first and the second. But then I realized that they are the same pattern and they are on all the rest of the negatives. The right side and in the middle and also a lot of black spots everywhere.
As it is a handmade obscura, is it possible that these are lightleaks?
Could it be that the film has some fault? Though I just don’t think that it would produce the same patterns.
Yes, the negs are not the best exposed and developed negs ever but I just started pinhole and to develop in trays so still trying to get the hang of it.
It’s Fomapan 400 in Rodinal 1:50.

bdial · Mar 15, 2020

Most light leaks don't show up as small spots like that, but a leak is certainly a possibility.
Try processing an unexposed sheet, if there are no spots, then the problem is in the camera. Otherwise, the spots could be a film defect or a darkroom problem.

Laci Toth · Mar 16, 2020

So the film seems fine.
What could be wrong then?
The camera? Probably but what?

grain elevator · Mar 16, 2020

What is that home made camera made of? If the back is thin wood or cardboard, there could be pores that let light leak in at the same spots in every negative. A layer or two of black paint should remedy it.

Peltigera · Mar 16, 2020

Laci Toth said:
Thanks for your response! Since then I was thinking about light leaks but it should be white on the neg not black, right? Because in case of a lightleak too much light would get in so it’d be burned. It’s more like no light affected those areas. I was also thinking about a darkroom problem, but the exact same patterns on all of them?
Will process a blank one and get back to you.

No, a light leak will always be black on a negative - it is a negative! The more light that reaches the film, the darker the negative. Still does not look like a light leak but if you are making your own cameras it could well be.

Ian C · Mar 16, 2020

See page 18 of the following Kodak document “Pepper Fog Spots”. It covers Kodak Printed Circuit Board film, but is the same phenomenon seen on occasion on photo films and papers. This can be especially a problem in the development of “lith prints”. Read the comments to get some ideas as to what might be happening.

https://www.kodak.com/uploadedFiles/Corporate/Industrial_Materials_Group/EN_pcb-artifacts-guide.pdf

This might not be the problem, but should be considered as a possibility.

Jim Jones · Mar 16, 2020

I agree with grain elevator. You could back a sheet of fresh film with a known opaque sheet such as tinfoil and leave the camera out in sunlight a while for a quick check for this.

Laci Toth · Mar 16, 2020

I put two layers of black tape on the camera and took two test shots.
All the spots are gone.
Thanks everyone for your input.

Spot patterns on negatives. Film defect?

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