Topic: Weirdly coincident film problems

[Indofunk]

We've all had those times where we did everything exactly the same ... same camera, same film, same speed, same developer/concentration/time/temperature (even in the same development tank) ... and the 2 films came out differently. This time, I used 2 very different procedures (though the same filmstock & developer) and the 2 films had oddly similar problems.

Film1:
- Cinestill 800 135-36
- Pentax ME Super
- ISO 1600
- C41 4 minutes

Film2:
- Cinestill 800 135-36
- Minolta SR-T102
- ISO 3200
- C41 5 minutes

Rolls processed sequentially in the same batch of C41.

And the results (sorry for cellphone pic):



See how at the very beginning of the rolls (top) there's a couple of "bands" of overexposure? And then about halfway down one film, and 2/3rds of the way down the other, there's a region (about the same length on each) of overexposure/light leak? (The overexposure goes all the way to the sprocket holes, so it's probably not me overexposing the frames)

Anyways, very weird stuff. Is there a simple explanation for this? There must be. Otherwise I'm blaming mischievous pixies trying to drive me insane

Can't say I'm displeased with the results, though

Banding:


Light leaks:








I may post a full photo essay later, but most of the rest of the shots look more "normal"

[Francois]

Looks like a light leak of some sort for the dark bands.

[Indofunk]

I assume so too, but in the same place on 2 different cameras at different times? It's those damn pixies I tell you 

Come to think of it, the light seal on one of the film canisters was slightly loose (the film pulled out quite easily without resistance), maybe 1. both of the canisters had loose seals and 2. there was a tiny sliver of a light leak that penetrated a couple of layers on the film? The first two bands are too close together, but the third band on each roll looks like it might be one full wrap away...

[Francois]

Very well could be. I've seen very variable quality in reloadable cassettes, so that might very well be it. The bands should loose density as you go further into the roll.

This got me wondering how thick the cassette spindles are?
I got my calipers out and measured 11mm diameter for one of my cassettes. That makes a 34.6mm periphery. But since the exterior of the roll is much bigger (the lightproofing flanges on mine are at 22mm), the distance between the bands at the beginning should be greater than at the start (about 69mm apart)... that is if it's the cassette that's at fault.

[hookstrapped]

I like the canister light leak suggestion

[Indofunk]

Ok, so then what about that huge light leak area in the middle (or 2/3rds through that other roll)??

[imagesfrugales]

Ok, so then what about that huge light leak area in the middle (or 2/3rds through that other roll)??

The pattern is very similar , so it is extremely unlikely that 2 different cameras are to blame and also the canisters are out of the picture imo.

Could it have happened during spooling the film into the spiral/tank? Otherwise I would blame the manufacturer. You could contact him wether the problem is already known. The bad canister sealings are also a sign that the production is not top of the line.

You could also sacrifice a film and develop it unexposed directly out of the box. My guessing is that you did nothing wrong, Satish.

[Francois]

As for the middle zone, I have absolutely no idea.
I'm trying to remember but I think other people here had problems with cinestill film....