I was looking at some negatives yesterday and noticed a slightly lighter streak on the left hand side of some frames. Only certain pictures are affected, near the beginning of the roll, interestingly all taken at the same place. The rest of the negative seems untouched. I scanned the whole thing to get a closer look and it looks like this. What could possibly have gone wrong ? I can't say it's development, the rest of the roll is fine and this was developed in batch with other films that all turned out fine. It has to be exposure, but how ? what could have caused this ?
Light leaks would show up on the long end of the images, not the short. And light leaks show up, in a positive print, as lighter, not darker.
I'm guessing you have a horizontal focal plane shutter in your camera. And the shutter curtains are not travelling across the film plane evenly. Meaning, they (or one of them) speeds up and slows down erratically.
Yes it's 35mm, and well light on the negative, dark on the positive
Yes I have a horizontal focal plane shutter (Leica M type).
So how come this problem doesn't show up elsewhere, on the same negative or even ones shot later with the same camera ?
It was cold that day but nothing like what we usually get here in Montreal and I've subjected this camera to much worse in the past. It was very very foggy and windy that day (not sure how that helps)
I don't see the other artifacts on my light table (that dark spot for example) but I do see a streak on the left side of the frame, it's on the negative for sure
Problems with focal plane shutters can be sporadic. Once a shutter has "warmed up" they may disappear only to re-appear after a rest period. So they may not appear on every frame.
The focal plane shutters are like autos every decade or so they need a routine service.
If you use them on cold days and bring them into warm house you get internal condensation which causes both corrosion and the oil to wax.
You need a zip lock bag and silica gel to get camera from cold outside to indoors.
Firing the shutter 500 times indoors might help or snap a ribbon...