dark strip on processed films

[Yan Preston]

some of my processed films have a slight darker strip running vertically about 1cm away from the edge opposite to the notch edge. It's irregular and hard to predict. It doesn't even seem to be consist with certain dark slides. It happens with whatever film... Has anybody seen similar problems at all and figured out what went wrong? Thanks

[Gem Singer]

A darker strip on a negative is a lighter strip on a print. More likely than not, indicates a light leak somewhere.

Could be the film holder. Possibly the camera. If you can post a picture, it would be easier to help to make a diagnosis.

[ic-racer]

Light leak close to the film. Perhaps a leak at the camera back.

[Diane Maher]

I have a few thoughts. Sorry for the long post.

Have you checked to make sure that your bellows is secured to your camera?

When your holder is in the back, is it securely in place and does it rest flat against the camera?

It could also be your bellows intruding into the shot. I have seen this before and determined that the holders were fine, but for some reason, either too much movement, or merely the shape of my bellows caused me to see such a line.

Take an empty holder, insert it into the camera as usual, pull the darkslide like normal. Remove any lens board and shine a flashlight into the camera. What you are looking for is whether you can see the entire edge of the film holder on the inside of a camera.

I had this happen on my Century whole plate camera when I was trying to take landscape shots using a modern Chamonix holder. I don't recall seeing it happen with the old Kodak holders I got with the camera. However, in landscape orientation, the bellows covered the end of the Chamonix film holder opposite the flaps by about 1/4 inch and when I developed the negative, there was a line across that edge of the negative.

Hope you get it sorted out.

[Gem Singer]

Diane,

If the bellows were intruding into the shot and blocking the light, wouldn't it show up as a lighter area on the negative?

Yan's problem is a darker strip on the negative.

Could also be a light leak during the processing procedure.

[Diane Maher]

True. :o I noticed that just before I hit send, but then was having trouble visualizing it and sent the reply anyway. All I could see in my mind was the dark strip on the print... Oops. :o Mind you, checking the fit of the holder in the camera back couldn't hurt either.

[percepts]

Could be reflection from inside of bellows, particularly with longer focal length lenses.
Could be light leak from around lens board so do the torch shinning on camera front whilst looking inside bellows from back test.
Does the dark strip go the other way across the film when you expose in portrait mode rather than landscape? If it does, then it is definitely an in camera light problem. If not, then it may be a developer tank filling problem. Which dev tank do you use and how do you fill it? Slow fill can sometimes leave streaks down a negative.

[Filmnut]

Sounds like a camera fit with to the holder problem. If the dark slide is pulled out for a longer time, does it get worse? Is it worse in high light (ie., bright sun) and gone in dim light? If so, it's likely some kind of a light leak.
Keith

[Yan Preston]

Hi everybody, thanks for all the replies. To make things clearer: the darker strip on the film always appears on the side without the notch. It happens with both landscape and portrait format; it happens with my two lenses: 150mm and 80mm; it happens on both B&W and colour which I process in different ways; recently I set the camera up and took 17 shots without any alternation of the camera between the shots (same shutter speed and aperture), about half of them have the problem. I did one test while I pulled the dark slide out but didn't open the shutter in order to see if there's light leak on the bellow, the processed film was clean without anything on it. I've checked the bellow again tonight it doesn't seem to be leaking, although I'm not sure if it intrudes into the shot or not. Somebody said it might be the reflection from the flap, I'm not sure. The trick thing is I can't predict when it happens or which dark slide will have it, so it's a bit strange. I've scanned one photo for you to have a look. Let me work out how to upload the image.

[Yan Preston]

Hi please have a look at this photo, the lighter strip was the darker bit on the film. Look forward to some clues!

[percepts]

well if its always on the long side of the film regardless of portrait and landscape orientation, then I would suggest its not a bellows or lensboard light leak. So it sounds like your film holder is not locating in the back properly. Is the line always on the same side of film, i.e. always left or always right of the film notch side? That should tell you whether its top or bottom side or both which are not locating properly. Could be worn out light seal depending on camera design. Mine has a black velvet which the film holder rests against.
What are you developing film in, Jobo tanks or something else?

[Yan Preston]

Hi, I agree that it's probably not the bellow or lens board. As you can see on the attached photo it's always on that side (the side without the notch), regardless landscape or portrait format. I need to check the light seal again. I develop B&W in a big tank which can hold upto 20 sheets in one go.

[percepts]

now I've seen pic I'd say it could be light seal on its way out. But since problem is intermittent I suspect there's a bit of operator error thrown in too. i.e. you aren't always locating the film holder properly or maybe not being careful enough pulling and replacing darkslide.

p.s. spring on back could be weak which leads to movement when removing and replacing darkside if care isn't taken.

[Louie Powell]

You may have already addressed this - but is this always happening with the same film holder, or are you experiencing the same problem with multiple film holders.

The problem appears to be consistently at the end of the holder that the darkslide goes into. It's not right at the end, so I would tend to rule out failure of the light seal.

[Yan Preston]

The problem keeps appearing on different holders. The same holder that had the problem before could be fine next time. Although I'm going to do a bit more test on this to make sure. I now think it's properly got some operating error plus the spring being weak?

[Louie Powell]

A weak spring could be the explanation,

I have had a similar problem with a Polaroid 405 holder where the darkslide handle is very short and difficult to grasp, making it all too easy to inadvertently pull the holder away from the back of the camera.

[Yan Preston]

If it's the spring, is there any way to make it a bit stronger?

[percepts]

dare I say it, bend springs if you can get at them. Depends on your camera back or get replacements if available.

[Yan Preston]

Oh well...I'll try and let you know what happens...

[Michael Rosenberg]

Van,

The problem may be not with the camera, but in the manufacturing of the film. I (ans some of my friends) have seen this with some batches of readyloads but not loaded sheet film. Arguing against this being a manufacturing problem is the fact that you also see it with your color film.

Is it of uniform density across the film, or is it less intense going to the center? If it is the latter then it sounds like a pinhole leak in the holder. Is it on both sides of a loaded holder - or just one side? It does not sound like fogging from the bellows or lens board. Does it vary with the length of exposure?

Mike

[Preston]

Just curious, but how are you developing your film? Do you develop all your film yourself? If so, you might want to check your system and workflow to see if there may be a glitch that is causing this. The reason I ask is the less dense strip on the negs could be caused by over development, or possibly a light leak, causing a reduction in density there.

-Preston

[Yan Preston]

Hi Preston,

I do develop the films by myself but recently I sent some films to a lab, they came back and had the same problem. So I don't really think there's a problem in the processing, unless we are all doing it wrong?

[Yan Preston]

Hi Mike, the darker strip is only on one side of the film (the side without the notch, as you can see from a photo I attached with a previous post). I think it is uniform density across the film, rather than less intense going to the corner. It doesn't vary with the length of exposure, sometimes it happens but more than half of the time it doesn't happen. Hope this helps?

[sgelb]

to me it looks like its inside your holders. a light leak of some kind.

[Paul Metcalf]

This is definitely an interesting problem. If it were a film holder seating problem, I'd expect to see the band extend to the edge of the film, instead it clearly shows up well within the frame, so I don't think it's a holder problem (also, it's random and varies with and without various holders inconsistently from what you've told us). How do you process, in a tank? Is there something at this depth in the tank that might allow for the film to attach (sometimes, sometimes not) so you don't get full development? Strike that, you said you got this same result from a commercial lab.

Do you have access to another camera in which you can use the same film and holders, and possibly use someone else's holders and film in your camera?

[Michael Rosenberg]

It really does look like a pin hole leak that is causing it to fog in one small area and direction. How are you storing your film? To me it looks less dense as the streak goes to the center of the film in the example you have shown. Do you have any other examples? Do you have any where it appears on a high light area of the film, e.g. sky?
Mike

[Yan Preston]

hi Michael, I used to store the loaded films in normal room light. When the problem appeared I stored the next lot of loaded dark slides in a dark bag until they were taken out and put into the camera. After the exposure they were then put back in a dark bag, although they were exposed into normal light area for a short period of time. Then these films were developed by a commercial lab, they came back with the same problem. As mentioned before I've got good and bad results from the same holder so I don't think light leak on folder would be the first priority. Although I'll check my camera again.

[Yan Preston]

Hi Paul, I'm going to do more test, hopefully with another camera too. I'll let everybody know what's happening. Here's another photo with the same problem.

[Paul Metcalf]

Good luck Yan. That last picture seems to show that most of the film is getting fogged to some extent, only the outside 1/8 or so isn't. If you haven't done so already, set up the camera outside in bright light, take the back off, and cover it and yourself as best you can with your darkcloth or even a large blanket. Let your eyes adjust for long time (minutes) to assess any leaks in the bellows/front standard. Repeat doing the same from the front with the back on and no lensboard. One reason this could be intermittant is that at different bellows extensions you might be getting a pinhole leak while at others (when the bellows is more collapsed) the pinhole is closed up.

[Gem Singer]

This one definitely looks like a light leak in the camera.

[Nathan Potter]

It's hard to invoke camera light leak cause that would produce such a uniform exposed line across the film at that specific location. I'd have to look at the seating of the holder within the back as being intermittent (human error?) since the phenomena is intermittent.

A thin line of light is reaching the film at a consistent point across the film plane. The shading off of the exposure laterally indicates a diffraction pattern exposure. Can't see how that could occur during development. Look for any other possible light leaks in the back assembly. It appears that they might be minor, but present. As another poster has suggested the effect is digital (it's there or it isn't) suggesting human error.

Nate Potter, Washington DC.

[Gem Singer]

Nathan,

I did not invoke anything.

Perhaps i should have worded my suggestion--from the appearance the last picture, the light leak doesn't look like it's coming from a faulty film holder. It's probably coming from the camera.

Look for a bellows leak or a poor fit between the film holder and the back of the camera.

[Preston]

After taking a close look at the color shot, I agree. Paul's test should show if there are any light leaks.

Not long after I got my used Tachihara I experienced some fogging. I waited until I had very dark night, extended the bellows, and, using a small maglite from inside camera I was greeted with what looked like a starry night!

-Preston

[Yan Preston]

The gentleman from the commercial lab that I used (Peak Imaging in Sheffield, England) suggested 'light reflection from the dark slide'. I've ordered a lot of films and will start doing a lot of tests soon. Will keep you all posted. Thanks.

[Yan Preston]

Tests results:
I took the camera in the darkroom, put a head torch in the bellows and confirmed that there's no leak from the lens board or the bellows. However, I noticed that the flexible metal piece on the camera back was quite weak (this is a China made Shenhao, it doesn't have a spring system on the back). When I put the dark slide in and out, if I'm not careful enough, the back will be accidently open a little bit and create a light leak. The solution to this is to squeeze the back and camera body together with my left hand, while the right hand carefully take the dark slide in and out. With this solution I did another 8 sheets of tests. With 4 out of these 8 I applied the new technique, the result had no problem. With the other 4 I did how I usually operate the camera, 2 out of these were fine. The other 2, I purposely created a very obvious gap so the sheets had a vague line and part of the film was fogged.

Somebody else suggested that the gap on the film holder where the dark slide goes in and out might be leaking, I'm unable to confirm on this one yet.

So far, I guess the weak spring and slightly rough operation might be the reason of the leak. However, given the fact that it wasn't consistent before, I can not guarantee this as the absolute cause. I'm going to start shooting normally using the new 'squeezing' technique, if the problem never happens again, I'll say it's cured. Otherwise I may have to change the system. I'll keep you posted.

[Louie Powell]

Well, damn! I've been processing film from a recent trip to California, and one of the negatives has a defect just like you described.

I reloaded and reused that same holder several times during the course of the trip. And the curious thing is that, for some strange reason, I opted to make two negatives of the first two scenes I photographed that morning, and only one of the negatives is flawed.

So it has to be the #1 problem facing LF photographers - dumb, human error.