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View Full Version : Suspected light leak with my 11x14



Sidney Cammeresi
2-Apr-2004, 09:43
Last weekend, I made some negatives with my Wisner 11x14 camera, a system which I'm just starting to get into. Two of the negatives were very badly overexposed, and one was so bulletproof that I'd say it was totally exposed. Coincidentally, these two were made with a new Nikkor 450/9 I've gotten, but I think that fact is a red herring. The margins of the negatives show halation where the rails of the film holder were, so I know this is something that happened with the film in the film holder. (I use S&S holders for 11x14.)

After much head scratching, I remembered another common fact about these two exposures. For one, I had to wait out some wind, and for the other, I had to wait out rapidly changing light. In both cases, I had the holder in the camera with the darkslide pulled for a long time, on the order of 15-30 minutes. My suspicion, therefore, was that there is a very small light leak either in the light trap of the holder or in the camera back that is insignificant when the exposure is made immediately, but is large enough to matter over the course of 15-30 minutes.

I scratched my head a bit more, and it seems unlikely that both light traps in the same holder would leak light in this way, and additionally, I would think that if the leak were there, that the exposure would be more gradated, with the top of the film being more dramatically overexposed than the bottom. (It wasn't.) I also discount the prospect of a somehow faulty bellows for this same reason. That leaves me with the camera back.

Given that the only thing keeping the light out of a Wisner with S&S holder inserted is a couple pieces of wood coming together, it seems plausible that this may be the culprit, and I suppose I could make things a little better by doing the old trick of draping the darkcloth over the back of the camera after pulling the darkslide. Do any of the geniuses out there have any comments to offer on my analysis?

Kevin Crisp
2-Apr-2004, 10:37
Sidney: In general, it is best to pull the darkslide (slowly so as not to attract dust) just before you take the picture. I would be uncomfortable with any camera leaving the dark slide out for half an hour. In theory you could do that but it is taking an unnecessary risk. That being said, if the negative is uniformly bulletproof and opaque except for the edges in the slots, I would first explore some other mechanical error like cocking the shutter when open, or pulling the slide before you close the shutter, etc. (I sincerely do not mean those as insulting, and all of us occasionally make such mistakes.) If you really want to know if this is a light leak, set up your camera in the darkroom with the same film holder in it, darkslide pulled, same lens on it, shutter closed, and put a bright flashlight in the camera. After your eyes have adjusted to the dark, turn the camera around on the tripod head and look for light leaks from all angles. Even very small leaks can be found this way. I find it particularly effective to do this with one of those little battery powered survival strobes, which can be leaned against the film holder inside the camera to focus the light there, or moved to the fron to test for leaks there. The on-off nature of the light draws your attention to even the smallest leaks. If you aren't finding a light leak in this manner, then some other explanation is probably it. Good luck.

MIke Sherck
2-Apr-2004, 11:21
Hi, Sid! Glad to hear that you're using the beast. We still expect to see you backpacking it this summer. :)

While echoing the previous poster's comments about looking for light leaks, I'm curious about what you mean when you say that two exposures were very badly overexposed. The Nikon is a modern lens with good contrast; if it's an overexposure problem the negative should still exhibit relatively normal local contrast but if non-image forming light has fogged them they should be of very low contrast. Perhaps you can use that to help determine the problem.

Finally, I always hang my focusing cloth over the back of the camera when a film holder is in. Trying to remove one more variable from the process. :)

Mike S.

Todd Wright
2-Apr-2004, 11:30
I had a friend that had the same problem. He started putting his focusing cloth over the camera when he had to leave the film in the camera for long awaited photos. He was also having problems with the bellows coming undone from the camera. Finely after having to do a photo section over twice and costing him a lot of money. He put a new bellows on the camera made by a different bellow company. Hasn't had a problem since. Still puts the dark cloth over the back of the camera not much can be done in that area of the camera. Check the depth of the lock groove that the film holder sits in, his was not the proper depth and that was also giving him problems.

Sidney Cammeresi
2-Apr-2004, 12:04
I really don't think this was a problem of pulling the darkslide with the shutter open or anything like that. I make those mistakes occasionally, but I always immediately know that I've made them, and it's too farfetched to think I would have done that twice and not noticed either time.

I did test the front of the camera for light leaks, as I suspected improper lens mounting might be at fault (I saw no leak), but I did not check the back. I intend to test the back and the film holder's light trap, and I will make a negative with all of the same equipment, but without the half hour delay between pulling the darkslide and making the exposure.

I guess on a windy day like that, I should probably come to my senses and instead get out a small format camera like a 4x5. :(

Michael Kadillak
2-Apr-2004, 14:03
Get in touch with Sandy King. I had the same problem with my 11x14 Wisner / S&S holders and he now paints the inside of the wooden flap and has a better design for the light baffle (black cloth) . I sent him my holders and he got me fixed up. Now all of the new holders have these features incorporated into them. It is always a good idea to drape a cloth over your camera and keep your holders away from any unnecessary light to the degree possible. I have Strebor septums for each of my S&S holders in 11x14 and 12x20.

All is not lost Sidney.........

Cheers!

e
2-Apr-2004, 14:18
Always treat the ULF like it is ultra light sensitive and you will have better luck. Your dark cloth is your best friend in this regard to counteract the light where it can get in. Be especially careful when moving the darkslide in and out. Perhaps grip the back tightly to make sure it doesnt move when you do this.Never leave the darkslide out a second more than the required amount for the process of removal, exposure, and reentry.

George Losse
2-Apr-2004, 14:52
Sidney,

There are a lot of things that can cause light leaks in ULF besides the normal things we think of.

Try taking the filmback off the camera with a holder inserted in the camera. Check to see if the film holder sits perfectly flat in the spring back. There is always a chance that something is in the way and not allowing the holder to sit flat in the spring back.

Also the lock bar on the holder might not be sitting in groove on the springback allowing the holder to raise up from the back. I have also found that some holder (and spring backs) stick and don't put the full pressure on the holder.

Brian Ellis
2-Apr-2004, 17:42
This perhaps isn't the cause of your problem but regardless of that I think that pulling the dark slide and leaving the holder uncovered in the camera for fifteen minutes or longer isn't a good practice. After getting a lot of light leaks when I first started using large format cameras I now make it a practice to toss the dark cloth over the back of the camera to cover the open end of the film holder, no matter what the lighting conditions are or how long the exposure is. I make plenty of mistakes, I don't hold myself out as a paragon of large format perfection, but I haven't had a light leak that I can recall since starting this practice 8 years ago.

Sidney Cammeresi
2-Apr-2004, 19:40
Thanks for the suggestions. I made a test negative tonight being more careful with how long the darkslide was withdrawn, and after development, the negative looked fine, so that's an easy fix.

Kirk Gittings
2-Apr-2004, 21:11
Sidney, Be careful still. You still may have a problem that needs to be addressed. For instance a faster film may fog with the slide drawn only a short time or direct sunlight at just the right angle may produce visable fog. I would be very uncomfortable proceeding with real shooting without determining the exact cause. I've that mistake a couple of times in my long career and had the same problem come back on me at the most inopportune times. Usually on commercial jobs we see the problem on the Polaroid, but we don't proceed until we are absolutely sure that we have found the exact problem. That may involve 40 polaroids, the flashlight trick etc. etc. The view camera that I use for commercial work has been in my service for twenty years, through three bellows and three polaroid backs. We carry an extra bellows and polaroid back just in case, because once in Telluride we had a light leak that we figured was in the polaroid back and continued only to find out when we got the film back that we had a bellows leak that only showed up when the lens standard was raised all the way up! We had to return and reshoot about half the job. Embarrassing and expensive! All of the potential problems mentioned by the contributers above are all good points. Find the problem or it will haunt you. Best of luck!

sanking
3-Apr-2004, 10:55
As Michael suggests we have had some problems with out 11X14 hiolders that resulted in a design change in the baffle. Therefore I do not discount the possibility that one or more of your holders has a light leak, and if so I will be happy to correct the problem even if your period of warranty has expired.

Others have pointed out that it is good field practice to pull the slides for the shortest time possible and to keept a dark cloth over the camera and holder at all time when working in bright light. I agree completely.

But, there may be a probelm. The three most common reasons for fogging are,

1. Light leak in the bellows, not likely in this case since your camera is relatively new.

2. Light leak in from the light baffle of the holder.

3. The holder does not fit correctly in the camera, i.e. the rib-lock on the holder does not fall into the groove in the camera back.

Check for #1 by putting a flash light inside your camera and in the dark inspect the camera from all angles. Put a film holder in the camera and check again, especially at the side where you insert the holders.

To check #2, remove the dark slides from your holders and with your eye at the flap end look back up through the baffles with a stroing light in the back. You will need to adjust the position of the holder to eliminate flare. If there is a leak in the baffle system you will see it with this action.

To check #3 insert your holder into the camera and make sure that the rib-lock falls into the groove on the camera back. If it does not you will definitely get a serioius light leak at this point.

Good luck, but as Kirk advises, please resolve this problem before wasteing a lot of negatives in the field. Nothing is more frustrating than a light leak on an otherwise perfect negative. Been there and done that and it ain't pretty!!

Ed Burlew
3-Apr-2004, 11:18
Last fall I drove three hours to a lakeside jetty to get a cloudy sunrise. I was so beat and had a new type of camera . I managed to put one film holder in from the wrong side. So I got a lot of lightleak. I realised that when I went to put in the second holder. I did the second and third holders correctly and I had all 6 negs developed. Maybe, just maybe, you fell prey to this type of simple error.

jonathan smith
8-Apr-2004, 02:36
You know, I've been having the same problem every time I use my Nikon 450 f/9, but wanted to play with it more before I put up a question. I got thin negs with very low contrast, and some look fogged as well. At first I thought I wasn't compensating the exposure enough for the bellows draw, so last time I overexposed and the negs look thick, but still low contrast. Like the shadow areas are gray rather than clear. I haven't printed them yet so will see how they look. But I get excellent results with all my other lenses. I wonder if the shutter speeds are off. Glad to hear everyone's experiences with that lens are good.

But my real point is to mention a light leak problem I had a while back. Most shots would be fine but every once in a while, a uniform fogging. You could still see the image but with color film there was a brown cast. The guy at the lab said I was putting the film in backwards! Not the case. Anyway, I got a battery powered stick-on flourescent light at the hardware store and put it inside. Everything was fine but a slight leak at the bail due to a warped film holder; and only one side of one film holder. So I got rid of that one, and as a precaution now I take a small bungee cord with me. I hook this to the back of the film holder and to somewhere on the camera, and this pulls the film holder forward so it fits tightly against the frame. After that, no problems. It occurs to me this might be an issue when the film holders are so large. If they are even slightly warped, they would create a light leak.