We had a drug store recently mess up developing c-41 in a similar fashion. All the sprocket holes had streaks that were much more obvious than the one in the original post. Rolls of film exposed 20 minutes before and after came out fine, and inspection of the camera showed no problems.
I'm not saying it is your problem, but the drug-store in question used the typical machine that is supposed to be fairly fool-proof, so it is possible to get these results with an automated process.
uneven exposure of the negative, but need more information. what kind of camera you using? Focal plane shutter? has it been serviced of late? Was this a fast exposure or slow one?
for example, if you have curtains on a horizontally running focal plane shutter not tracking evenly, and the two curtains are catching up to each other at times, that might give you this sort of banding effect, especially at a high shutter speed where the traveling slit is narrow and variations would show up more starkly.
this is highly unlikely to cause this sort of banding, however -- usually when that happens you get one end of the film unexposed, the other exposed.
you don't make it clear that this is nowhere else on the whole strip of film -- if it is, that might indicate a development problem -- lack of agitation, perhaps? Developer flowing over the film slowly instead of through proper agitation might explain the relatively even spacing of the banding because it flows through/around the sprocket holes.
I agree. The spacing of the bands makes sprocket hole drag unlikely. With a horizontally running focal plane shutter, this banding is much more apt to occur at the highest shutter speeds. Avoiding them may be the quick cheap alternate to a clean-lube-adjust on the camera.
Jim, if it would be the shutter, all my images should be wrong which were taken after this shot. But the next roll had 36 almost perfect exposures.
So the next roll( same camera, same make of film and same lab) was perfect? If the answers to these questions are "Yes" then it would seem to point to something going wrong at that lab on that particular processing session.
If you are a regular customer and it values your business then if they don't think you are about to slap a big compensation claim on them you might get an honest response to the effect that something might have gone wrong.
Worth a try. You could rely on us coming up with the right answer but neither you nor we will ever know if we have got it right.
Referring to my previous post, my theory on the film we had developed, seeing that the drug store developed two rolls and one was fine, is that either the machine jammed to an extent, or perhaps something momentarily happened with the chemical levels/flow. Just a thought.
Also possible that it is a light leak through the light trap on the cassette if you wind the film right in and expose to a bright light source. This will always happen with IR film if you take the cassette out in the daylight, and the banding looks just the same...I know, I've done it!
Realize that this is not IR, but there is a slight chance this could happen?