light leaks in film holder or elsewhere

[jonathan smith]

I have been experiencing light leaks with my 4x5 film off and on for about a year. The most aggravating and non-comprehensible problem is after development, when certain negatives will have very obvious solid stripes of exposure (or lack of) running though them. The stipes (usually only one stripe) are parallel to the borders and are consistent in their over or under exposure. They are usually at least one inch wide. When printing, I cannot seem to burn or dodge away this problem. I have tested all my film holders, so the only other variables are-

-the film box I used to store shot film while traveling

-my changing bag

-my camera, but I doubt it

It has only happened with a couple of negatives, which makes diagnosis very hard.

If anyone has run into this problem, please let me know. Also, is film below 800 speed susceptible to X-ray damage in airports? Is paper OK to put through an X-ray machine?

Thanks-Jon

[tim atherton]

what camera?

[Donald Qualls]

We can let out X-ray damage immediately, unless the film was loaded in holders when it got X-rayed. X-rays would damage all the film in a box in the same manner; even in holders, I'd expect all the holders to have similar damage if they were stacked together, and both sheets in a single holder should be effectively identical. And X-ray damage would never produce underexposed strips.

Presumably you've controlled against an obstruction in front of the lens; have you verified you don't have something potentially loose inside the camera? Those would produce underexposed strips, but not overexposed. Are the strips sharp edged, or fuzzy?

If you're using a focal plane shutter (as in a Speed Graphic or Graflex), you could get both if there were problems with the shutter curtains -- a hole would give an overexposed strip, while a trailing flap could cause underexposure, and both could be intermittent. At right angles to those, hangups in the shutter movement could cause over- or under-exposure, even both in the same negative.

[Denis Pleic]

Jonathan, how are you developing the negatives?

It could be the developing....

I've had some problems at the beginning of my 4x5 development in a Jobo processor and 2509N reel. I've had strips of underdeveloped (or "underexposed") negative close to the edge, parallel to the reel guides.
It turned out that the rotation speed on Jobo processor was too slow. Once I started using faster speeds, the problem went away.

Denis

[Eric Biggerstaff]

Jonathan,

I recently had a similiar situation which turned out to be a light leak in one of my cameras. I use a Zone VI 4X5 and the bail springs were not tight enough so the film holder was a little loose. The leak caused a 1/4 inch wide band of over exposure along one end of the film that was parallel to the short side of the film.

I sent the camera to Richard Ritter who fixed it quickly.

[Andrew O'Neill]

Gee whiz, this is a strange one. Bands of over or under exposure...when a band appears, is it right against the edge of the film? Do the underexposed bands appear on the edge of the film? Where do the over exposed bands fall? Do they consistently fall in the same place?

[Brian Ellis]

The first paragraph of your inquiry makes it sound like this happened a lot ("off and on") over the course of a year. Then in the second paragraph you say it's only happened with a couple negatives. Also, you say the stripes are consistent in their under or overexpsoure. What does that mean? As I'm sure you know, light leaks don't create underexposure, they create only overexposure. When you refer to an underexposed stripe and light leaks, are you assuming the underexposed stripe was the correct exposure and the rest of the film was overexpsoed? Obviously I don't exactly understand what you're seeing or how often you're seeing it, which makes it difficult to diagnose the problem, especially if it's only happened a couple times.

However, if it's only happened with a couple negatives in the course of a year, and each time it was a single solid streak or band running parallel to the edge of the holder, it doesn't sound like an equipment problem to me, assuming you used all your holders multiple times during the year and you had this problem only a couple times. That sounds more like operator error to me, e.g. those couple of times you didn't get the holder properly seated in the camera or you left the camera in the sun light too long with the dark slide pulled or any number of other mistakes we all occasionally make. I don't think xrays are the likely culprit unless you put the film in your luggage and even then I believe xray damage shows up as fogging, not a single streak parallel to the edge of the holder but I've never had an xray problem so I could be wrong, I don't know exactly what it would look like.

"We can let out X-ray damage immediately, unless the film was loaded in holders when it got X-rayed."

I routinely run loaded film holders through the carry-on xray with no problem. It never occurred to me that a film holder would provide less protection than a cardboard box.

[Donald Qualls]

"We can let out X-ray damage immediately, unless the film was loaded in holders when it got X-rayed."



I routinely run loaded film holders through the carry-on xray with no problem. It never occurred to me that a film holder would provide less protection than a cardboard box.



What I meant was that, if a whole box got X-rayed, the damage would affect every sheet in the box almost identically. Only if the film was in holders would you get one or two sheets affected and the rest okay. In fact, I'd expect a film holder (especially an older one with metal film sheath and dark slide) to provide more protection than the cardboard film box -- but if you get zapped anyway, you might only lose one or two sheets, not a whole box at once.

[Patrik Roseen]

You are not saying how you develop your film and which equipment you are using. I have experienced the same problem once and that was due to me not filling my combi-plan tank with enough developer (slip of memory) and therefor the developer did not cover the whole sheet while they were resting between agitations. The effect is a very clear stripe since this area only gets developed during agitation and the developer ends up in exactly the same position when agitation stops. Light leaks usually have more fuzzy effects.