Light leak or processing error?

Thefic · Feb 29, 2020

Hello all.

Recently had a few rolls (HP5+, TriX, and Double X) that are all exhibiting the same issues. Only towards the last 10 frames of the roll.

Dark patches on the negatives. Lighter areas along the middle of the frame.

Not sure if this is a camera light leak, a Paterson Tank light leak, or a processing error.

Photos of the negatives attached.

Thanks for all the help.

Truzi · Feb 29, 2020

In one scan you seem to have images of sprocket holes (dark areas of the same shape) between actual sprocket holes, with fairly sharp edges - and it lines up with the fogged part of the image. I'm going to guess that suggests fogging while the film was rolled up - like on the take-up spool in the camera.

Check the back of the camera and see if the light seals are intact.

When I had a similar experience, it was only when I had the camera case off - the case had covered the camera back. In addition to having the case off, i had a longer delay between taking pictures, allowing enough light through a space between the camera back and the body where the light seal had degraded.

Agulliver · Feb 29, 2020

Which camera did you use? Does it have a little window on the back door to enable you to see what film is loaded? I am betting the foam seal around that window is in need of replacement. I've seen this a few times with various cameras of mine and the result is fogging pretty much exactly like you have. You can get the foam very cheaply on eBay and cut it to size or buy a "kit" for many cameras.

Thefic · Feb 29, 2020

I'm using a Canon AE-1. The seal looks pretty good. I checked it after I first noticed the issue.

What is bugging me is it is happening randomly.

I shot a roll of Kentmere 400 at box speed with no issues. Then a roll of tri x pushed to 1600 that only had 3 frames affected. Then a roll of HP5+ pushed to 800 with 9 frames affected. The HP5+ has so far seen the worst.

But the affected frames are not always next to one another. Example from the last roll. 4 good frames. 1 affected frame. Then 5 good frames. 2 affected frames.

Neal · Feb 29, 2020

Dear Thefic,

It is almost certainly a light leak in the camera. When I have similar problems, I load the camera making sure I have several unexposed frames on the take-up reel. Then I expose the one frame and leave the camera out in the sun for ahour with the back facing up. Advance another 5 frames or so and repeat, this time with the camera facing the sky.

Unload the camera and develop normally. The first test will show you how well your light seals are working. The second (far less likely) will test the shutter/mirror system.

Once developed, you can use the exposed frame to show you where the light leak is by aligning it with the shutter. Don't forget that the image will be upside down.

Good luck,

Neal Wydra

Peltigera · Feb 29, 2020

That is clearly a light leak near to the take-up spool. Unprocessed film is rather opaque and the effect of a light leak here depends entirely on the time between shots. Less than a minute between shots probably does not allow enough light to penetrate the film to have a noticeable effect. A couple of hours between shots will produce a more noticeable effect and a few days between shots will produce a very noticeable effect. This will account for the intermittent appearance of the leak.

Agulliver · Feb 29, 2020

It could be that the light leak is tiny and is only affecting the film when sunlight falls on the camera back. You could try putting some processed negatives in the camera and seeing if the fogging lines up with any openings that should be light tight. Foam seals can look good while still letting in tiny amounts of light.

As Peltigera says, if you wind on several shots in fast succession you may notice nothing whereas if you take a shot then leave the camera even in dull light for a few days that could be sufficient to fog a frame, while leaving adjacent frames perfectly fine.

Thefic · Feb 29, 2020

Thank you for the info.

I will test today as stated and leave the camera in the sun face down and then again face up after advancing the film.

I've ordered a seal kit just for good measure.

mrosenlof · Feb 29, 2020

I agree that it's almost certainly a camera light leak. It could well depend on direct sunlight falling on a particular camera part. Your hand on the camera when you're shooting may well cover the spot in question because I kind of suspect the area under your right hand when shooting -- where the exposed film is rolled up on the take-up side.

Vaughn · Feb 29, 2020

One of the factors that determined the amount of fog you got would have been how long you took between winding to the next frame. The longer the film did not move, the longer an area got fogged before the film was advanced.

Light leak or processing error?

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