RB67 Light Leak?

SodaAnt · Aug 3, 2023

I recently received an RB67 from KEH and exposed a roll of film to test it. In some of the images on the roll (all of the same scene) it looks like what may be a light leak.

In the image, there's a lighter area that looks like a vertical bar about 1/4 of the way into the frame from the left hand edge. Of the ten negatives about 1/3 have this line and it's always in the same place. The only difference in the images is that they all were exposed at different shutter speeds (with the aperture changed to keep the exposure the same)--is it possible that the light leak is more visible on frames that had a longer exposure time?

I'm wondering if I should discuss this with KEH?

ags2mikon · Aug 3, 2023

Check the foam in the back, the revolving adapter and the rear of the camera. I have had to replace mine in the past. Also the dark slide may be leaking. I haven't had that happen yet.

SodaAnt · Aug 3, 2023

ags2mikon said:
Check the foam in the back, the revolving adapter and the rear of the camera. I have had to replace mine in the past. Also the dark slide may be leaking. I haven't had that happen yet.

This is an RB67 Pro-SD with a Pro-SD film back. Don't this use a different kind of light trap that doesn't use foam?

reddesert · Aug 3, 2023

Post a picture of the full film strip including the rebate (area outside the image) so we can see if the leak extends beyond the frame.

SodaAnt · Aug 3, 2023

reddesert said:
Post a picture of the full film strip including the rebate (area outside the image) so we can see if the leak extends beyond the frame.

Unfortunately, I cut the strip up into two exposure pieces to fit in the scanner. I checked the images on a light table with a loupe and for all but one image with the line there is no increased density in the rebate.

The one exception looks like below. The line goes across the image starting at exactly the point where the edge is dinged (physically damaged). I did have problems loading the reel when I developed this roll (due to not having done it in many years!) Can these lines be due to the film being loaded on the reel incorrectly? I'd think that if the film was touching itself at some point that would result in lower negative density at that point due to less developer reaching the film.

Sirius Glass · Aug 3, 2023

Let KEH fix the problem for you. No risk to you.

reddesert · Aug 3, 2023

The attached picture with the dark marks - I assume those are dark on the negative - is weirdly sized, but assuming those are small crescent dark marks (sort of like a fingernail clipping), yes those can come from buckling the film as you load it on the reel. I don't think the straight line across the frame as in your first photo has anything to do with them.

I didn't mean that you should scan the rebate, but that often a picture as simple as a phone picture of the filmstrip against a light table, white monitor screen, etc is revealing. If the light leak stops at the edge of the image area, that means it is coming from in front of the film gate. So you can check the seating of the roll holder to the back, light seals of the back frame, etc, but you can probably rule out light seals in the back door /hinge of the roll holder. That kind of reasoning.

SodaAnt · Aug 4, 2023

reddesert said:
The attached picture with the dark marks - I assume those are dark on the negative - is weirdly sized, but assuming those are small crescent dark marks (sort of like a fingernail clipping), yes those can come from buckling the film as you load it on the reel. I don't think the straight line across the frame as in your first photo has anything to do with them.

The attached picture with the dark marks are dark on the negative and it undoubtedly is the result of the film buckling during loading the developing reel. There is a white line in this frame through the picture area and it lines up exactly with the buckle mark on the edge of the film. The other two frames with definitive white lines through the picture area do not have this type of mark at the film edge, but I'm thinking the film jumped the track on the reel and the film was touching in one or two places. Unfortunately, I didn't check for this while the film was still on the reel after development was complete.

One puzzler is the fact that two of the frames that have the white line have them in different places in the frame. Both are landscape oriented frames and the first one has a vertical white line 1/4 of the way into the frame from the left edge and the second frame has a vertical white line almost dead center in the frame. If this was a light leak, wouldn't the position of the white line be consistent?

If the light leak stops at the edge of the image area, that means it is coming from in front of the film gate. So you can check the seating of the roll holder to the back, light seals of the back frame, etc, but you can probably rule out light seals in the back door /hinge of the roll holder. That kind of reasoning.

That makes sense. I looked closely at the seating of the roll holder and of the back itself and didn't see anything obvious. This RB67 and the back are both PRO-SD and I've been told it doesn't use foam light seals like earlier models did.

Could another possibility be not a leak per se but a shiny reflective area inside the camera body that reflects light onto the film when the shutter is open?

Donald Qualls · Aug 4, 2023

Straight lines in a vertical (right angles to the film length) orientation on an RB67 are most likely leaks in the film back hinge line, though possibly bad felt in the dark slide slot (this would usually be more spread out) or a leak at the latch (this would also usually be more spread and you'd be able to see that the latch wasn't closing correctly). The ones that are worse are probably an inch or so AFTER the frame that was in the gate when the film stood a little longer than the others.

As a test, put a piece of gaffer tape over the hinge after loading the back and before advancing to frame 1, then shoot a roll slowly with direct sun shining on the back hinge. If there is now no leak, a hinge leak is confirmed.

FWIW, all my RB67 backs have tape on the hinge, and my Graphic 22 and 23 backs are about to get some.

SodaAnt · Aug 4, 2023

Donald Qualls said:
As a test, put a piece of gaffer tape over the hinge after loading the back and before advancing to frame 1, then shoot a roll slowly with direct sun shining on the back hinge. If there is now no leak, a hinge leak is confirmed.

I'll give that a try. I plan to expose another roll this afternoon and develop it over the weekend. Last time I did this the camera was in complete shade while exposing the film. This time I'll put the camera in direct sun and see if that makes the issue, if it exists, more obvious.

Depending on the results of this test I'll speak with KEH on Monday and see if I can return the camera to them for repair or replacement. I purposely chose a camera from KEH in Ex+ condition rather than Ex or Bargain or Ugly condition on the hopes that what I got would not have functional issues, but it appears that KEH's rating system only covers cosmetic condition, not functional condition. To have caught this issue, they would have had to do a test with film, and I doubt they do that. I suppose buying any camera used is a crapshoot and this time I came up craps.

Donald Qualls · Aug 4, 2023

SodaAnt said:
it appears that KEH's rating system only covers cosmetic condition, not functional condition.

I'd disagree with that, but their testing does not extend to film testing, so they aren't likely to catch light leaks (other than bellows pinholes, perhaps).

Otherwise, if you read their descriptions of their ratings, all of them above BGN include something along the lines of "fully functional" -- they check for shutters and mirrors working and speeds that are at least close, film advance mechanisms that at least show correct mechanical operation without film, etc., features that in general serve as proxies for previous owner(s) having take some care with the camera. This combined with their return policy makes KEH one of the few where you can actually trust their condition rating.

SodaAnt · Aug 4, 2023

Donald Qualls said:
I'd disagree with that, but their testing does not extend to film testing, so they aren't likely to catch light leaks (other than bellows pinholes, perhaps).

That's good to know. Thanks.

Regarding RB67 film backs, how consistent should the frame spacing be? The spacing between frames on my back seems to be wider at the beginning of the roll and narrower towards the end. The difference is perhaps 25%. Is this within the bounds of normal? My Hasselblad backs have very consistent frame spacing and I'd have to measure it with a caliper to see any deviation.

Donald Qualls · Aug 4, 2023

SodaAnt said:
That's good to know. Thanks.

Regarding RB67 film backs, how consistent should the frame spacing be? The spacing between frames on my back seems to be wider at the beginning of the roll and narrower towards the end. The difference is perhaps 25%. Is this within the bounds of normal? My Hasselblad backs have very consistent frame spacing and I'd have to measure it with a caliper to see any deviation.

This doesn't match my experience with RB67 backs, but all of mine are Pro or ProS models, not ProSD. The ones I have use a drive roller to count length rather than turns of the takeup like Graphic roll backs (the latter requires a cam to adjust how many turns per frame as thickness builds up, and had to be adjusted when film got thinner in the 1980s-1990s). This friction drive length counting is why RB67 backs will give correct spacing with 35 mm film (assuming the actual drive wheel has been locked to the roller in some way).

SodaAnt · Aug 4, 2023

I shot another roll of film today, alternating having the camera exposed to full sunlight and covered up to shield it from light.

To eliminate yet another variable, I’m having the local lab process the film. Then I can be sure that any strange lines on the negative are due to light leaks and not me bungling up the development.

Donald Qualls · Aug 7, 2023

SodaAnt said:
I shot another roll of film today, alternating having the camera exposed to full sunlight and covered up to shield it from light.

To eliminate yet another variable, I’m having the local lab process the film. Then I can be sure that any strange lines on the negative are due to light leaks and not me bungling up the development.

Seems reasonable for a one-off, though in practice, these days, I'd have to send my film away to be processed (nearest actual lab vs. send-out service is more than two hours drive away in Charlotte).

SodaAnt · Aug 16, 2023

Got the roll I had the local lab process back and the light leak, if it's there at all, isn't obvious. Looking at the negatives, and the JPG scans the lab provided, I don't see any smoking gun.

Here's an image I scanned from the negatives. This is probably the worse-case as far as showing any light leaks because the camera was in direct sun and the shutter was open the longest out of all of the exposures (f32 @1/8 second). Film, once again, is Ilford PanF Plus, this time unexpired (expiration date: 05/2024). I shot the roll the day before it was dropped off at the lab. They say they developed the film in Ilford ID-11.

The first roll I developed myself had no frame markings, but this one did. I suspect this is the infamous PanF Plus issue of the latent image disappearing if the film is not developed soon after manufacture.

Any comments? The sky doesn't has very little, if any, of the mottling the first roll had. I'm surprised that lab-processed film has as much dust and other gunk on it. I thoroughly cleaned the negative carrier glass and bed of the scanner and blew dust off the negative before scanning.

Anyone see any sign of a light leak?

SodaAnt · Aug 16, 2023

Here's a frame that was shot at the shortest shutter speed: f8 @1/125 sec.

Donald Qualls · Aug 17, 2023

I surely don't see any leaks. Rebates look good? If so, it may just have been age damage to the first roll.

My experience is that only the door hinges are really prone to leaks on the RB67 and its film backs, but I haven't used them that long.

MCB18 · Aug 17, 2023

It looks like in your last few posts you may not have had an actual light leak, but I’ll give my $0.02 anyways.

If it is a Pro-SD back, then all but one of the light seals on the back itself should be mechanical, so no foam to degrade.

The darkslide has a thick piece of rubberized foam that prevents light leaks, which doesn’t degrade nearly at all from what I’ve heard, so that’s probably not an issue.

The revolving back adapter does have foam, and if you do have a leak, that almost certainly the culprit. Check to be sure all of that foam is still fluffy and not degraded. If it is, it’s not too hard to replace yourself.

Finally, the spacing issue. No, the back should have equal spacing between all frames, or, as close as practical. I’ve attached a photo of some 220 hanging up, showing that spacing is pretty much identical throughout the entire roll.

Arthurwg · Aug 17, 2023

Donald Qualls said:
As a test, put a piece of gaffer tape over the hinge after loading the back and before advancing to frame 1, then shoot a roll slowly with direct sun shining on the back hinge. If there is now no leak, a hinge leak is confirmed.

Why gaffer tape? Much too sticky. I used back masking tape.

Donald Qualls · Aug 17, 2023

Arthurwg said:
Why gaffer tape? Much too sticky. I used back masking tape.

If you have that handy, so much the better. Gaffer is a bit more opaque, but black masking tape should be adequate. Mine have black electrical tape, because I had it.

SodaAnt · Aug 17, 2023

MCB18 said:
Finally, the spacing issue. No, the back should have equal spacing between all frames, or, as close as practical. I’ve attached a photo of some 220 hanging up, showing that spacing is pretty much identical throughout the entire roll.

Here's a photo showing frame spacing. Definitely not equally spaced.

MCB18 · Aug 17, 2023

SodaAnt said:
Here's a photo showing frame spacing. Definitely not equally spaced.

Ahhh, yeah, that’s still fairly consistent and normal. I thought you meant you were getting something more along the lines of what some Kievs do.

Donald Qualls · Aug 17, 2023

With that level of unevenness, at worst your advance system and counter may need cleaning. If it run smoothly and doesn't make crunchy noises, I wouldn't worry about it.

Alan Edward Klein · Aug 17, 2023

SodaAnt said:
Here's a photo showing frame spacing. Definitely not equally spaced.

I get unevenness like that with my RB67. Maybe it depends how fast or slow you move the film advance lever. Wouldn't the thickness of the film have an effect as well? Thinner film might slip more.

RB67 Light Leak?

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