View Full Version : Help diagnosing 7x17 light leaks (not a newbie, but still)

G Benaim
5-Nov-2018, 11:22
So, I finally got my 717 going and just developed some negs, and about half had some sort of light leak. The holders are s&s and the camera is a folger and schwing w a back tailor made by Ritter to match these holders. In the more severe leaks the back was uncovered but in shade, on the others the back was covered by the dark cloth but in full sun. All the leaks occur on the flap side fwiw. I'm guessing it's my technique when pulling the ds, though I made it a point to hold the back down as well as keep it covered, so not sure what's going on.

Fred L
5-Nov-2018, 11:29
do you feel the rib locks engage with the back when inserting the holders ? second photo looks like holder not inserted all the way maybe ?

fwiw, I have original holders and newer AWB for my Korona 7x17 and haven't experienced leaks like this.

Good luck sleuthing the cause ;)

G Benaim
5-Nov-2018, 11:34
The holders lock down really well, as I said, the back was made for them. But that's one of the shots where the back was uncovered, so either the fit isn't quite as tight as it shld be or I did something wrong when pulling the slide or replacing it.
I should also mention that I tested the holders w paper and had no leaks in full sun for 20 minutes, but this is 400 Asa film.

Fred L
5-Nov-2018, 11:42
Just checking to make sure the back is actually locking onto the ribs. If I don't feel the snap, I usually tug the holder to see if it moves. Will look at my camera later to see if I can see what might be the cause, but sounds like light is sneaking in between the back and holder somehow.

5-Nov-2018, 12:01
What has your test in a pitch-dark room and a flashlight inside the camera shown you?

Lachlan 717
5-Nov-2018, 12:31
Have you checked that the back itself is bedded properly into the main body?

G Benaim
5-Nov-2018, 12:45
Yes, I checked the back w a holder in it in the dark w a flashlight and no leaks. I'm starting to think it's when I pull the ds, that maybe the back doesn't stay flush when applying pressure. What else can it be?

5-Nov-2018, 12:56
Do the test again; set the light in the camera pointed towards the back, put the lens back on, and (in the dark, of course) pull the darkslide in and out a few times.

But frankly, the worse of your fogging seems to be out-of-camera, since the rebate is heavily fogged.

Jim Noel
5-Nov-2018, 13:14
Get a wide point black felt pen. Use it on all surfaces on the flap and the area where the flap seats. I had the same problem with these holders, and this solved it.

G Benaim
5-Nov-2018, 13:27
Vaughn, that's a good point about the rebate being fogged in the second one, so that would mean the film was fogged prior to being loaded? Or at least not while in the holder?

5-Nov-2018, 14:10
Perhaps; the other two show fogging along the outer edge of the rebate. The only way I can figure that could happen is out of the holder. I doubt light can pipe that far under the film rail.

If you have a collection of negatives that show a progression in the degree of fogging (all at the same end), then the worst was on the top of the stack and the least at the bottom when they got light-struck. The anti-halation layer provides some protection for the lower sheets of film.

5-Nov-2018, 14:48
How many holders do you have? Are they double sided? If double sided do you get leaks on both sides or just one?

My money is on the holder(s). Light can travel pretty darn far into a holder if the light trap is trashed for some reason.

William Whitaker
5-Nov-2018, 15:57
I don't understand how a back can be made for a Folmer & Schwing 7x17 because the Folmer & Schwing banquet camera have an integral back which is not removable. What exactly did Mr. Ritter make?
I'm just trying to visualize the camera itself. For now Vaughn's suggestion seems to make a lot of sense.

Thom Bennett
5-Nov-2018, 16:14
Even once you diagnose the problem I would suggest ALWAYS have the dark cloth over the back when you put a holder in, pull the dark slide, and remove the holder from the camera. These old cameras are so damn finicky.

5-Nov-2018, 16:18
Image number two is bellow vintage.

G Benaim
5-Nov-2018, 20:12
Ok, obviously more testing is needed. The holders are fairly new and in good shape, and the other negs I developed from a different box have no fog, so will dev some more and report back. Thanks everyone for the help so far.

G Benaim
5-Nov-2018, 20:15
He replaced the original w a bail back and changed the rib in the back into a channel so it could accept korona style holders, but he can obviously explain the procedure in more detail if he's reading.

G Benaim
6-Nov-2018, 02:01
Well it looks like Vaughn was right, the film is the problem, so that's an easy fix. I deved another batch, half from the problem box and half from a different one, and the ones from the problem box show the same kind of fogging along the flap end and somewhat along the rebate, while the other film has none, as before. Given that all were shot in similar conditions w exactly the same equipment, the only variable is the film. Thanks all for your help.

Lachlan 717
6-Nov-2018, 02:27
Good outcome!

Now, go forth, shoot and post the results.

6-Nov-2018, 07:37
Glad it was not the camera or holder. Those are expensive. Were these new boxes of film?

G Benaim
6-Nov-2018, 09:16
The problem film was a box I got w the camera and holders, about half full.

6-Nov-2018, 11:32
Glad we could narrow it down to the film. Have fun with the camera!

I modified an 11x14 darkslide to make two 5x14s on an 11x14 sheet of film. Mixed luck so far, mostly due to having several types of holders and not covering the camera sufficiently with the darkcloth.

Michael Kadillak
8-Nov-2018, 09:00
Just to be safe I used matt black paint and painted the side channels, the flap area and unscrewed the light trap and painted that matt / flat black. Remember, taking the holders out of the light tight septum and getting them under the dark cloth and into the camera back is another risk for a light seep event. I also put a piece of hinge tape over each of the side hinge cuts on the bottom of the holder. Film is expensive.

G Benaim
8-Nov-2018, 10:05
Thanks, Michael, good advice. I am being much more careful w 717 but as I said the problem seems to be limited to a film box I received w the camera and not the gear or technique.

Michael Kadillak
8-Nov-2018, 11:16
Thanks, Michael, good advice. I am being much more careful w 717 but as I said the problem seems to be limited to a film box I received w the camera and not the gear or technique.

I fought light leaks for months with ULF. Finally I decided to stop playing games and went after the issue with a vengeance. Also sent the rear GG camera housing back to Ritter to take excessive play between my S&S holders and the camera back. Only after these multiple iterations then did I get past the rapids to the smooth water. I would not want to jump to the conclusion that all ULF has commonality with these issues but retrospectively, now that things are "fixed" life is good.

G Benaim
8-Nov-2018, 12:21
I hear you, light leaks can drive you nuts.

8-Nov-2018, 14:56
The problem film was a box I got w the camera and holders, about half full.

Maybe someone opened it to count how many were there. :cool: