Light Leaks caused by loosly wound roll

[rick_strome]

I have had my Hasselblad 500C and two 12 backs for over 30 years and

all of a sudden in the last 6 months I have been getting a random

light leak fog on about 5% of the shots I take. I mostly shoot Kodak

400 NC.

The leak fog is a very slight haze that runs horizontally across the

film. It ranges from 1/16" to 1/8" wide and covers from 1/2 to 3/4 of

the width. The fog leak also covers the film border. The density

varies from very slight to noticeable. In all cases the leak is not

a series of streaks that might be caused by a light leak through the

light trap. Also, there is always an image visable where the fog is.

When I first noticed this I had my back serviced and reserviced

finally by Hasselblad to corect a film overlap problem. Hasselblad

thinks the problem is caused by the film not being tightly wound on

the takeup spool. Kodak thinks the same so I am sending some of the

exposed film with the leaks to Kodak.

I know it is not a camera light leak because when I take the dark

slide out, I put a large piece of duct tape over the slot where the

dark slide would go. Still a light fog doing this.

Has anyone experienced this and if yes how do you solve the problem?

Is the problem with the film or the back?

I try to wind the film as tight as possible on the takeup spool to

try to avoid this problem but it still happens about 2 - 3 frames

every 60 shots.

Thanks for any advice on the above situation.

Rick

[art_haykin]

If your dark slide light trap is worn, you COULD be getting aslight leak between the time you pull the slide, and installthe tape. Hard to say.

[peter_rosenthal]

Yo Rick-

Many things can cause a light leak. My bet here is the twisted fiber of mystery material

in the small channel in the back case edge where the magazine mates with it. It may

have become compressed over time and thereby allowing light to strike the film from

between the magazine and the case at the place where it is most vulnerable (where it

reverses itself as it goes around the spools in the magazine) ALL ACROSS THE FILM,

even the edges. Quite common in older backs.

 

Other things to look for...the barn doors on the body may not be closing properly.

Another common problem with older bodies that is often overlooked and rarely

considered. Light can easily strike the film when the shutter is cocked (open) if the

doors are not closing properly. This is easy to see. They should not move when touched

VERY LIGHTLY from the front before the body is cocked. Another very common

problem with older bodies.

 

The tabs that hold the back onto the body may be worn. Check for looseness in the back

while attached to the body. A little movement is normal but outright looseness is not

good as light can reach the film between the body and the back. Also...if the body/back

assembly has ever received any impact, the front plate on the back may not be flat at

the bottom causing some gaps (gaps is bad!!) where there should be none.

 

Finally...it's not likely that the film is not winding tightly. It's the take-up spool that

drags the film across the aperture and through the back. One helluva load. The

backlash prevent mechanism (causing it to loosen AFTER winding) may be defective but

not likely as Hassy shoulda and woulda seen this and fixed it. It would most likely still

be overlapping if this were the problem anyway.

 

I'm assuming the light trap is OK. Even if it weren't, you wouldn't get fog on the edges

of the film. If you e-mail me I can give you a test roll procedure to test for all of

these issues.

 

Peter - PR Camera Repair - Flagstaff, AZ

[william_baguhn1]

If the film isn't winding tightly, that means that when you take out an exposed roll, the paper is bigger in diameter than the 120 spool edge. Usually, it's (about) .125" farther in from the edge.

 

I have encountered this several times with my camera (not Hassy). The fog pattern tends to be a triangular shape, or a heavy band with no visible image.

 

I don't think it's loose film winding.

[arden_howell]

Rick: I recently had a very similar fogging problem with my Hassie and an A12 back. The fog pattern sounds very similar, including the film edge. My local repairman didn't think it was just a light trap problem, but replaced the seals anyway as a starting point. Guess what? Problem solved! If you can borrorow or rent another back, you might quickly rule out anything to do with the body itself. Also in my experience, streaks from loose film usually occur only towards one end of the roll. Good luck.

[derek_simpson]

Perhaps you should sacrifice a roll of B&W or if you're feeling miserly a cut piece - load the magazine remove the dark slide and hold the camera close to a strong lamp at the suspect angles - and perhaps a frame with the lens off and shining in through lens mount to see if the rear curtains are light proof. Quick cheap and either useful or reassuring. Try your hardest to fog the film and see iof you succeed. Very long shot - is the film tightly wound from the packet ? has been known though usually asssociated with import brands

[rick_strome]

Thanks for all the above answers.

 

Comments:

I only get 2 - 3 leaks every 5 rolls of film. Thus if I did a test I might not get any leaks.

 

The leak is a slight fog where there is an image visable where the

light leak fog is.

 

I had the backs serviced by Hasselblad and the light trap foams replaced. It is not a light leak through the area where the dark slide goes. That type of light leak would be sharp streaks of light instead of a slight fog.

 

When finished, I wind the film as tight as I can on the takeup spool to help insure it is tight, but still get a few leaks now and then.

 

I am asking if it is possible for the back to wind the film loosly so light can leak through the loose areas or could the film be wound such that the light could leak through.

 

Thanks, Rick

[peter_rosenthal]

In answer to your question of whether the back can roll the film loosely thereby causing

light leaks...the answer is no. The two issues are not at all related. You can slightly

increase the film tension on the take-up spool by slightly bending the chrome steel

spring plate that rides on the paper of the supply spool and/or take-up spool. This won't

help you with light leaks tho as stray light shouldn't be anywhere near the emulsion

whether the film is loose or not. You should be able to make it fog by setting the back,

attached to the camera or not, in a very light place (not in the direct sun, heat is bad)

for a long time. Try 1/2 hour for starters. Light leaks are always time dependent.

 

PR Camera Repair Flagstaff, AZ

[todd frederick]

I would get light leaks randomly as you are...only when I took out or put in the dark slide and only in bright sun. It IS the light seals in the film backs that are causing your problem. I have read that these should be serviced (changed) about every 2 years if you use your camera a lot. There is no harm in having them checked.

[ken_pargett]

I, too, recently had a loosely wound roll of Kodak 160 Portra film. We were on a family portrait shoot with our 500C/M and A-12 back, and when we finished with roll #1 (to our horror) we realized the film was not tightly stretched as we licked and sticked.

 

We immediately hid the roll in our camera bag and even wrapped it in black plastic after we got home.

 

Our worst fears came true - the last three exposures were hazed to varying degrees on the edges. All threee shots were lost.

 

Luckily, there were enough great pictures for our customer to choose from.

 

Regardless, we are worried about using the Kodak film again and cognizant of the potential for problems with any film brand. Now, when the last frame is exposed, I wind the film magazine like a sailor hauling up an anchor.

 

Ken Pargett

Syracuse, Nebraska.

[raymond_valois]

Hi Ken ...

 

I don't think that the problem is related to the film. I do wedding photography and must have shot at least 200 rolls of PORTRA NC 400, 160 and VC 400 and 160 over the last 3 years or so. I use the Pentax 645N.

 

I have NEVER had any problems with the films, no loose winding, flatness or fogging on the film. I really believe that there must be a problem either with your winder or the sealing of your back(s).

 

Ray

[don_feinberg2]

I have consistently had "roll-light-leak" problems with the TMAX films. I have no problems whatever with any Fuji films, nor any problems with Agfa films -- hundreds of rolls have been wound up just as tight as you like.

 

But with TMAX? There is almost always a problem -- at least in 3 rolls of 4. I can feel (and hear!) some misalignment of the backing paper on the 10th, 11th, 12th exposure, and in winding off the roll. There is clearly some small dimensional difference in the TMAX backing paper (I haven't measured with the necessary precision!).

 

I don't know what the problem is -- but it is clearly real.

[tgofine]

I had a similar problem with one of my A12 backs. The seals

were replaced, but the problem remained episodically. Once I

began to pay extra attention to how I handled the film once it was

rewound and out of the magazine just before I folded the end

and sealed it closed, the problem disappeared. I wouldn't have

believed it, but I have to admit that seemed to be the problem: I

was somehow careless.

Tim Gofine

[victor_randin]

In spite of your experiment of covering the slot with a duct tape, change the light seal. Thirty years, it is just exact time to do it, isn�t it :?)

 

Sounds like light leaks caused by bad light seal, the horizontal lines partly evidence it. However the 12 back might get loosen, and a very small light leaking throw a chink appearing between the body and the back is enough for Kodak 400nc as for a very sensible film.

 

If the film isn�t tightly winded you should get uneven space between frames. It would say that the brakes-spring into the takeup spool spindle is broken. Check this spindle also, it may be turned easily in one direction only with no looseness.