Streak running through multiple neg frames

Dave@Toronto · Sep 15, 2020

Hi all, first post on Photrio.. long time reader.

I developed a roll of HP5 last night and there is an underdeveloped (dark) streak running through the middle of a few frames. This does not continue across the entire roll -- only a half dozen or so frames in the middle of the roll are effected. I've never seen anything like this before and wondering if anyone has an idea what could cause this? I'm skeptical that it has anything to do with the camera, and assuming something went wrong during development. All other frames on the roll look perfectly normal.

I've attached a picture so you can see what I mean.

Donald Qualls · Sep 15, 2020

Dark on the negative is not underdeveloped -- that would be light on the film, dark in the print. What you have there looks like light fogging that occurred either in camera or during loading the film into the developing reel.

Slightly possible is it could be a "pressure mark" -- some (most?) emulsions will fog if the film gets sharply bent, whether directly due to pressure or due to triboluminescence of the halide or something else in the emulsion (or of the film base, possibly). A kink during loading the film, either in the camera or into the developing reel, could produce this kind of mark. On medium format they wind up looking like a crescent, because of the way the larger film kinks, but I can see how a longer mark like this could occur with 35mm.

foc · Sep 15, 2020

Look like an erratic light leak of some sort.
How did you load the dev tank reel?
In a dark/changing bag?
The line isn't straight so I would think it's not the camera.
Could be a light leak when loading the film onto the reel.

cmacd123 · Sep 15, 2020

considering the film looks "Bent" near the fogging, I would agree with Mr. Quails on this one. Pressure fogging

Dave@Toronto · Sep 15, 2020

Thanks for your replies. I don't see any bends in the film and I'm pretty gentle when loading the reel. I did pull the film out of the canister, whereas I usually break the canister open and remove the spool... I wonder if that could have caused pressure as you described (although it would be no different than the pressure that is applied when the film is extracted and spooled back up in the camera)..

The light leak is a possibility: I loaded it with a changing bag but did have lights on so I suppose it's possible that some light momentarily slipped through the arm holes, although I've used that same changing bag in the light many times without incident. I'm also pretty sure it's not the camera... the camera is in really good condition and I was out in very bright sun shooting and changing lenses, and most of the roll is fine.

Dave@Toronto · Sep 15, 2020

cmacd123 said:
considering the film looks "Bent" near the fogging, I would agree with Mr. Quails on this one. Pressure fogging

I think that is probably just an illusion because of how the photo was taken, but I'll take another look at it to be sure. Thanks!

MattKing · Sep 15, 2020

Could it be an un-fixed portion of the negative? If so, it will be a different grey and will appear as if on the surface.

Rudeofus · Sep 15, 2020

Just curious: that slightly larger patch which I encircled in red: is this a scanning artifact, or was there a cloud in the original scene, or is this also an image defect?

runswithsizzers · Sep 15, 2020

Test your film loading bag in a dark room with a bright light inside. Look for a pinhole in the fabric. If you don't find anything, can you show/describe what the ends of the streak look like - where it starts and stops?

Dave@Toronto · Sep 16, 2020

Rudeofus said:
View attachment 255110 Just curious: that slightly larger patch which I encircled in red: is this a scanning artifact, or was there a cloud in the original scene, or is this also an image defect?

That is likely a cloud -- photo is of an airplane and it was a partly cloudy day. I haven't printed a contact sheet yet but will be able to confirm once that is done.

Dave@Toronto · Sep 16, 2020

runswithsizzers said:
Test your film loading bag in a dark room with a bright light inside. Look for a pinhole in the fabric. If you don't find anything, can you show/describe what the ends of the streak look like - where it starts and stops?

Good idea! I will do that. I should note that I did develop another roll of film after this roll and it came out fine... Same changing bag. Now that I think of it, same stop and fix mixtures as well so that is probably not the culprit. I always mix fresh developer and used a different tank/spool.

The ends of the line just trail off... e.g. you can see a break in the line in the middle of frame 15 in the photo I posted. It trails off like that at the ends as well.

runswithsizzers · Sep 16, 2020

To me, the most likely explanation is some kind of light leak in the changing bag. Possibly a brief leak from a loose arm sleeve, or a pinhole in the fabric. Hard to say which without testing. I assume you were not wearing your smart watch in the changing bag.

Dave@Toronto · Sep 16, 2020

runswithsizzers said:
To me, the most likely explanation is some kind of light leak in the changing bag. Possibly a brief leak from a loose arm sleeve, or a pinhole in the fabric. Hard to say which without testing. I assume you were not wearing your smart watch in the changing bag.

Lol, no I wasn't wearing a smart watch but that would certainly be an unfortunate mistake I have however certainly ruined more than one print from forgetting to put my phone in my pocket and having it ring and light up the darkroom. Luckily the consequences of that mistake are little.

I'm going to inspect the bag more closely. After hearing everyone's input on this I think that is the most likely culprit. Will follow up if I can arrive at a firm conclusion.

Really appreciate everyone's advice and input here!

Streak running through multiple neg frames

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