Edge fog: Oh, those smoky rebates…

We’ve all read the admonitions on the film boxes, the data sheets, and the manuals for our medium format cameras (you did read that, right?): load and unload in subdued light. So you do. And then you get a roll of film back from the lab, or you start to unspool a wet strip from your Paterson tank, and there it is… The dreaded edge fog, smoky little mountains emerging from the very edges of the film and extending well into the rebate, or perhaps even into your image area. In my case, I mutter a few choice words, and start to wonder if it’s just me.

Well, it’s not just me, and regardless, edge fog happens. So let’s explore why, and how you can best avoid it.

What is it, and what does it look like?

For those just coming to medium format film, edge fog is pretty simple to understand: Light has somehow, at some point, leaked between the inside edge of the spool flange (the round parts on the ends of the spool), and the backing paper. That leaked light, in turn, made it to the film, and it’s happily exposed the edges of the emulsion in fun (not), random ways.

With 120 roll film, it’s difficult to completely avoid it, and most of the time, it stays in the rebate area (the edges where the frame numbers and film identification information is found). Occasionally, it might extend slightly into the image area. The good thing about medium format is you have so much real estate, even if it gets into the image, you can easily crop it out in a digital workflow (or in an analogue one for that matter) without losing much image data. But that fact makes it no less annoying.

To put some visual context onto this, here’s an example of a photograph I took on a recent vacation. This photograph was taken with Lomography Color Negative 400. (More on that below.) Look specifically at the right edge. I’ve made this image clickable so you can view the full-size example.

By and large, the image is fine. Viewed at small enough resolution, it’s not that noticeable, and if I’d not pointed it out, I’d wager that some readers wouldn’t actually notice it. But that foggy white edge on the right side is nevertheless annoying, and that’s edge fog sneaking far enough from the edge that it seeped into the image itself.

The problem is a bit easier to see on the negative itself:

See all that dark fog on the right side? This negative is cut and sleeved into PrintFile sheets, and the image in question is on the last strip of images on the roll. The previous strip, just visible above to the left, has some minor edge fog that’s typical of the fogging I often see, and it doesn’t extend into the image area.

Why does it happen?

Knowing that it’s a light leak makes it pretty clear what’s going on, but that doesn’t fully explain it of course, and there are a handful of very specific causes. They include:

  • You didn’t follow the directions. (Subdued light is your friend.)
    Loading and unloading your 120 film in subdued light isn’t just a suggestion, it’s a requirement. The problem is, unless you have a replaceable back camera like a Hasselblad, a Mamiya 645 Super or Pro, or something similar, you’re inevitably going to have to end-up changing film in the field, and putting your back to the sun to shadow your work just doesn’t cut it most of the time — especially with many specific cameras (see below). Always try to load and unload in as dark a setting as you can possibly find in the situation you’re in, while still being able to see what you’re doing.
  • Your camera isn’t necessarily your friend.
    The design of certain cameras doesn’t make the situation any easier. (I’m talking to you, Mamiya C220 and C330.) Part of the equation here is ensuring that the backing paper is nice and taught on the spool — and stays that way — during loading, and during shooting. The problem is, those Mamiya C-series TLRs don’t do a damned thing to help you during loading. On the contrary, the design of my Rolleiflex Automat MX helps in two ways: There’s a tension spring in the film roll cavity, and there’s a bar you have to thread the film under, and both work in concert to ensure that there’s tension on the film. That helps avoid looseness on the feed spool that can let light in during loading, and helps make sure the take-up spool has tension too when it’s time to unload. Hasselblad and Mamiya backs also have a film path that sort of forces a certain amount of tension. But no matter what camera you have, do your best to keep that tension throughout, and if your camera is working against you, it makes low-light loading all the more critical.
  • Poor handling. (Black bags and foil are your friend, too.)
    I’m reasonably convinced that most brands of sealed, unexposed film are wound tightly and accurately enough that you’re unlikely to cause edge fog until you break the factory seal. I bought several rolls of expired Kodak 120 film a few months ago, and all of them were out of their packaging, and totally bare rolls. They were that way in the store’s expired bin, and they’ve been that way in my refrigerator, and they’ve not exhibited any edge fogging after shooting them. This pretty much tells me that edge fog, if it happens, is something happening when I load, unload, or handling the roll after exposing it. As a result, I always, always take the precaution of wrapping the exposed roll in foil, or placing it in a black zipper bag. (I bought a package of them on Amazon for this purpose.) All the care in loading and unloading in the world won’t help if strong light gets to the exposed rolls — especially if your camera doesn’t wind them tightly along the way. (See above.)
  • Maybe it’s the film?
    I am utterly convinced that not all films are created equal. To date, I’ve not experienced edge fog on a single roll of Ilford film, and I’ve had very slight fogging on perhaps a roll or two of Kodak film. Lomography films, on the other hand, have been a pain; I don’t think I’ve shot a single roll of Lomography Color Negative film (100, 400, or 800) that hasn’t had edge fogging, and it’s one reason why my love affair with Lomo has been muted. I still love Lomo CN’s color rendering, and I still shoot their color film (in large part because I bought so much of it). But while my opinion is subjective and empirical, I strongly believe that Lomography’s films have poorer manufacturing tolerances, or something else is going on here that’s unique to their color films. Could it be coincidence? Perhaps, but I’m unconvinced. Regardless, it makes proper care and handling (the stuff above) all the more important.

The bottom line

Edge fogging seems to be a bit of a fact of life in 120 roll film land, and it’s abundantly clear that certain cameras exacerbate the situation with their film path designs. In most cases, it’s nothing that’s going to make it to your images, and taking some basic precautions will go a long way to keep it from being any worse than it has to be.