Light leak after a brand new seal set?

[connor_roelke]

I was sorely dissapointed to see some streaks of light on three images. I have just replaced the light seals, too.

500c, 80/2.8 C, A12 back (pre 12-release).

 

Can anyone identify what could be wrong? Keep in mind, this was pretty badly overexposed. I would say 2 or 3

stops. But it appeared in the same place in two other images.<div></div>

[paul_gardener]

There are two ways to check a film back for light leaks.

The easiest way is to remove the darkslide, hold the frame part of the back under a desk lamp while you let the side of the back that is near the opening for the darkslide touch the lamp.

Any leaks should appear now.

 

The other way that can be used without a lamp is to remove the darkslide, let it rest at the side of the back as a shield for day light and watch for any leaks.

I wish I had pictures to show it. They would be easier to explain.

 

If the darkslide canbe inserted and removed without noicable friction it may be necessary to curl the

metal strip some more to improve the sealing.

This is done most of the time before the new seal is fitted and sometimes neglected.

[q.g._de_bakker]

Connor,<br><br>At first glance, it's not clear what caused this. But it is not a faulty dark slide slot light seal.<br><br>Looks more like some internal reflection. You mention it was badly overexposed, which might explain the blotch extending above and below the actual image, over the bit that is covered by the rollers in the film gate. The 'shadow' of the right hand side (you are showing the image left-right reversed!) is a puzzler.<br><br>Something to look at and think about for a bit longer!

[leicaglow]

The other thing I noticed about your image is the weird edges. Could it be that your film isn't winding correctly? It looks like it is warped, especially along the bottom edge.

[connor_roelke]

Yes, sorry about the flipped image. I forgot to change it before I posted it.

 

It should be noted that this leak stopped completely after the 4th frame. It should also be noted that on a long exposure (10 seconds I beleive) I had a strange problem. The edges of the film were curled greatly and it had a line where a small portion was correctly exposed and the other part fogged. What could be wrong?

[john_layton]

There are some possible variables here that you did not mention: how long is the camera idle between exposures? Is the filmback itself being held tightly enough to the camera? And is it in proper alighnment with the camera? Is the secondary shutter (two black flaps) closing fully between exposures? Is the mirror rising up fully - or is there perhaps a space left between the upper body casting and the edge of the mirror during some (or all) exposures?

 

Looking at the pattern of extraneous light (and resultant shadows) across the frame in your example, my gut tells me that light is leaking in from the side - and that possibly the lightseal job was not done properly (what were your exposures like before this?) or there is some attachment and/or alighnment problem between camera and back.

[q.g._de_bakker]

Curled edges??? Could they have been melted, burned up by the heat projecting an image of the sun on the film for a

longer time? Hmm...<br>Was that on the same film?<br><br>I ask, because the light over the bits where the rollers

would have protected the film agains a leak makes one think about light piping: strong enough light will bounce back

and forth inside the layers of the film, travelling quite a distance that way. "Strong enough", because the film contains

pigments to absorb light that tries to do so. But if the light of the sun, concentrated by the lens in one small spot, is

burning the film for 10 seconds...?<br><br>Internal reflections in lens and camera could also cause effects, not

unsimilar to the ones your picture shows. Here's one i made earlier:<br><br><img

src="http://home.tiscali.nl/qnu/PN/Reflection.jpg"><br><br>The sun was just out of the frame, to the right. Needless

to say, the sunshade used was woefully inadequate.<br><br>Anyway, i do not believe it is a light leak through the

slot you have just gotten a new seal installed in. That looks completely different.

[connor_roelke]

I'll try and provide a few more details.

 

This was the third exposure that I shot in relatively rapid succession. No more than 4 minutes in between them. After every exposure, the dark slide was put back in and removed immediately before the next exposure then put back immediately. A light shade was not used.

 

The only reason that I don't think it's any of the things that you mentioned Q.G. is that it was only visible in the first four exposures. Is there any chance that I could have produced this in developing afterward? I do my own developing.

 

I appreciate all your help everyone. I think I'll try to finish this roll today and take a look.

[savagesax]

How new is your dark slide? If it's bent at all a dark slide can wreck your new light traps. REplace the traps and perhaps buy a few new dark slides.

[q.g._de_bakker]

I'm rather sure that it is not due to a dark slide slot seal. So before spending money on slides and seals, better look

for what <i>is</i> causing this.<br><br>It only being visible in the first four (so not just the third?!) exposures may

suggest a film handling error during loading too. Which could also explain the fact that the fogging runs across the

bits that are protected by the frame edges in the magazine.<br>But on the other hand: the first four... that's perhaps

a bit much to fog during loading.<br><br>What do the first three exposures look like? Is there a pattern in the fog

running continuing across all four, i.e. larger than the individual frames? Or do all individual frames show the same

pattern (more or less)?<br><br>And have your films been (recent, or in a more distant past) on a trip on board of a

commercial airliner?