What causes fine vertical lines on a C-41 negative?
Asked 9/1/2018
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I’m home-developing C-41 film with a Tetenal Colortec kit in a Paterson tank, using stick agitation and a controlled water bath. I can see fine vertical lines on the actual negative, so it doesn’t seem to be a scanner problem. The film was shot on a Hasselblad 500 C/M, so a focal-plane shutter issue seems unlikely. Could this be caused by uneven agitation or another processing problem, or should I also be looking for camera-related causes such as film transport stress or a light leak?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
7y ago
2 Answers
1
I think there are three plausible possibilities in general:
- shutter problem with a focal-plane shutter;
- scanning problem;
- development problem, probably agitation;
- light leak in the camera or around the edges of the roll, or keeping the roll somewhere there is very bright light.
From what you have said (1) and (2) can be ruled out: the camera has a leaf shutter, and the lines are on the neg.
I don't think it's (4) because the lines look too closely-spaced to me: whenever I've had light-related problems with 120 (due to the exposed roll seeing strong sunlight) it's been clear that light is getting in around the ends of the roll, and also through the backing paper in a broad band. So I don't think it's this.
So I think it must be (3): agitation or some other processing issue. And as you're processing it yourself & colour is fussy about agitation as it's designed for continuous agitation I think this is very plausible. The glib answer is 'buy a Jobo', although they're terribly expensive (and the one I had was not electrically safe).
Originally by user82065. Source · Licensed CC BY-SA 4.0
user82065
6y ago
0
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If the lines are visible on the negative itself, it’s not a scan artifact. And with a Hasselblad 500 C/M’s leaf shutter, a shutter-banding issue is very unlikely. Based on the answers, the most likely cause is processing—especially uneven agitation or another development issue. Fine, closely spaced lines are less consistent with the usual 120 light-leak pattern, which tends to appear broader and often near the roll edges. Another possibility mentioned is mechanical stress during film transport, though that would usually come with signs that the film was being pulled or advanced roughly. It’s also worth confirming you used enough chemistry to fully cover the film in the tank. So the best first place to troubleshoot is your developing method: verify proper chemical volume, consistent agitation, and stable process control. If the problem persists across rolls, then test with another camera or another lab/process to rule out transport stress or a camera issue.
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AI7y ago
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