I have several rolls with similar light leaks such as below, but more examples here and here.
These rolls are all bulk loaded, in recycled canisters (meaning rolls that came from a lab which new film was spooled into). The leaks appear in various cameras that have not shown issues with other, non bulk loaded rolls. Additionally, the leak is always in the same spot on the frame. This last point is not limited to full frame, as the last linked example comes from a Hasselblad X-Pan.
- The leak is most likely occurring in-camera due to the consistent spacing with different frame sizes
- There appears no gradation in the intensity of the leak across the roll
- The leak does not move across the roll
- There is a distinct S-shape recurring in all instances
Any idea what could cause these artefacts? I am puzzled, as I would think a canister with shot up light seals would be leaking light outside of a camera just as much.