The Importance of Light Seals

Let me begin by admitting that I’m sick and tired of film photographers telling other film photographers not to worry about their light seals because they’re not necessary.  This is complete and total bullshit and the inspiration for this post.  There’s nothing more infuriating in the world of film, for me, than the spread of misinformation.  Don’t be an anti-vaxxer!  I’m going to set the record straight!

Regardless of if you don’t use high speed film or view light leaks as art, you need to replace your decaying old light seals.  Don’t scoff, read on!

Perhaps the most beautiful light leak, ever.  This frame came from an Agfa Optima Sensor Flash in 2008.  This is a bizarre camera that opens both from the back and bottom and is therefore capable of some very thought-provoking leaks.

In the early 2000’s when I started shooting and knew little about film photography or maintaining classic cameras, the foam rubber light seals common in 1970’s SLR’s were often times still good enough to shoot with at 400 ISO or lower.  I could shoot all day and night and not even know what a damn light seal was!

But it only took a few years before I began using higher ISO films and picking up bodies whose light seals were crumbling or smooshy.  Today, in 2019, I promise you, that ANY vintage SLR which has not been properly serviced in the last few decades, NEEDS NEW LIGHT SEALS.  And hey, replacing light seals is cheap and easy so let’s not keep avoiding it, okay?

There’s no such thing as a Pentax Spotmatic that either hasn’t been serviced in recent memory or does not need fresh light seals!

What cameras have and need light seals?  Here’s a general list.

–Most 35mm SLR’s (pre-1970’s German ones sometimes use black string or felt instead of foam rubber)

–Most 60’s and newer Japanese fixed lens 35mm rangefinders

–Most medium format SLR’s

Light Leak in a Nikkormat FT2 using 400 ISO film indoors after just coming in from outside with the film wound, the next shot was clean!

If you’ve recently discovered one of these cameras and would like to use it, at minimum, you should replace its light seals.  Ideally, all vintage cameras should also be Cleaned Lubed and Adjusted (CLA’d) by a professional repair person too.  The days of finding a vintage classic camera in your parents closet and then loading it with film and a battery before going off and shooting up the world, are over.  This is just a sad fact.  And we need to be clear about this, else we’ll destroy our cameras.

And here’s why:

As foam rubber light seals age, they either crumble into little bits or they get mushy, gummy and misshapen.  So when you find something like a Pentax K1000 or Nikon FM, simply remove the lens and GENTLY press your finger onto the black foam rubber strip above the flipping mirror.  If that strip breaks apart or it squishes instead of bouncing back into shape when you remove your finger, your light seals are bad.  All of them.

GOOD mirror bumper light seal in a Pentax K1000 SE.  If your mirror bumper does not look like this, replace ALL the seals in your camera!  Do it!

Same thing in the case of something like a Canonet or Yashica Electro rangefinder.  But since you cannot remove the lens, you’ll have to check the foam inside the perimeter of the film compartment.  This may require pressing it with a small wooden stick for example.  It’s a little difficult to see but what you’re inspecting is the same.

Light Leak in an Olympus XA using 400 ISO film in overcast light

So what’s the big deal, right?  What if you only shoot 50 ISO indoors or you LIKE light leaks?

The problem is that the foam will continue to fall apart with use anyway.  Every mirror slap, every film door close, will cause this foam to deteriorate further, delivering tiny bits of sticky old rubber into the camera and screwing things up.

There are some folks out there who are very vocal in various film photography forums who advocate being cheap and not addressing foam light seal decay.  I guess they think they know better than camera manufacturers.  They probably also believe that the earth is flat.  Don’t listen to these people.  They are not real photographers.  They are camera hoarders who don’t take care of their many cameras and shoot on them even less yet seem to talk a lot in internet forums.

Here’s what not only CAN, but WILL happen if you keep using a camera with decayed light seals:

–Bits of foam can stick to the view screen in SLR’s.  These screens are merely a plastic fresnel panel imprinted with very fine concentric circles.  It is nearly impossible to remove decayed light seal foam from these when it becomes embedded.

–Another common problem is the frame counter reset tab.  Inside the perimeter of the film compartment of most 35mm and 120 cameras is a small metal tab.  When it is pressed by a corresponding tab on the film door, the frame counter is reset back to 0.  Because light seals are in the same channel as this tab, the foam can get into the camera body here, and jam the frame counter mechanism.

–Regardless of if your camera has a fresnel screen or frame counter reset, the foam bits can get on your film, ruining your photos.  And in all reality, decaying foam bits can probably cause other issues too but these are the just the most obvious, factual threats.

Light Leak in an Olympus OM-1 with 400 ISO film indoors, a result of opening the film door mid-roll.

If you enjoy light leaks, you can achieve them in a more controlled way by occasionally opening the film door mid-roll.  Fresh seals will prevent metal on metal, and sometimes glass to metal wear on your camera.

The good news is that most repair shops only charge something like $30 to replace light seals.  And if you’re strapped for cash, don’t have a local shop or just prefer tinkering and learning camera repair, it’s very easy to replace ones own light seals.

Light Leak from the film reminder window of a Fujica AX-3 using 3200 ISO film indoors at night

Some newer 35mm cameras have a film reminder window, like a Fujica AX-3, Voigtlander Bessa R or Nikon FM10.  The foam rubber strip around this window will also have to be replaced.

Speaking of the Fujica AX-3, some SLR’s, some Leica R’s, will have thin panels of foam rubber or felt encasing the entire inside of the mirrorbox.  This is unusual and poses a bit of a service issue.  If you have a body like this, I’d recommend not replacing the seals yourself but seeking professional service.

But for the rest of you, you should be fully capable of replacing the foam rubber light seals yourself.  If you’d like, I can write a blog about that at another time and provide the link here.  But there are numerous great videos and articles on this already.  They just need to be followed rather than ignored!

Alright!  I think that about does it for my square-off against the anti-light seal crowd!  If you have any questions, just let me know in the comments.  I’m happy to help or argue about light seals as necessary!

Thanks for reading!

The featured image is a rare light leak; from a Leica IIIc.  This body’s tolerances are so beautifully tight that no light seals are needed.  So what caused this?  A missing screw, believe it or not!  Wow, Leica’s are funky!

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20 thoughts on “The Importance of Light Seals

    1. Happy to help! I have been taking a camera/lens or two ever few months to my repair guy for the last two years, trying to get through all my cams that need attention before I no longer have such a great local resource. Best of luck!

      Liked by 1 person

  1. My Konica C35 needed the seals replaced and initially I just taped up the back with black electrical tape when I loaded a film but that wasn’t really convenient, especially when I then had to clean the sticky residue off the back of the camera. So I decided to do it myself, which was a first for me.

    In the end it was a simple procedure but very tedious. I think I went through around 50 cotton buds cleaning everything up, but it was worth the effort. I also decided to make it easy for myself and just buy a pre cut kit of seals. That and the abundance of information on the web including many videos means that anyone can do this. There are no excuses.


    1. Olli, I embarrassingly also taped up the back of my K1000 in college, when the internet was younger and I was clueless! Yes, tape is a bad idea for its sticky residue, potential cosmetic damage to the camera and sheer inconvenience of loading/unloading.

      Glad you learned to replace the seals yourself though. On some models, and when you’re new to it, yes, the process can be a little tedious. Once you’ve refoamed a few though, you pick up little tricks to make it easier. You’re right though, getting the bad foam out is maybe the most tedious part. But it shows how important it is to get them out of there!

      Thanks for reading/commenting!


  2. PREACH.

    I let the light seals in my Nikon F3 go too long. Last time I used it the focusing screen got little light-seal bits all over it. Fortunately, that screen comes right out and I was able to clean it. But I’ve *got* to replace those seals before I use the camera again.

    Liked by 1 person

    1. It happens to the best of us, letting an otherwise camera go to pot due to decaying seals or a corrosive old battery. But we’ve gotta take our equipment more seriously! The value of film, film cameras and our work will only increase as time goes by.


    1. The thing with light leaks is that they are largely circumstantial. And many people do not shoot under the conditions that favor them, at least not frequently. Years ago, I shot on my ME Super constantly and didn’t change the seals. Worked fine at 100 and 400 ISOs. Then I went out to in the snow with 400 ISO. The snow reflected the sun so brightly, I got light leaks.

      There’s nothing mysterious about light seals and leaks. I think when you are in a mode of buying tons of old cams, cheap, you aren’t as committed to caring for each one they way it deserves so corners are cut. I get it because I used to do this too!

      Liked by 1 person

  3. Such a good post! I find myself getting sucked into Facebook conversations where someone is asking about having their light seals replaced or investing in a CLA and someone else will say, “it’s not worth it, too expensive, just buy another old camera instead.” If you love a camera and enjoy using it, have it serviced…or at least invest in new seals! Some of these cameras are 30, 40, 50 or more years old–they deserve some spa time! Geesh!

    Liked by 1 person

  4. I’m one who owns a Fujica AX-3 with an oxidizing/drying rubber substance coating the entire inside of the mirror box. I’ve replaced the light seals myself, but have no idea how to tackle the mirror box issue. Any suggestions on where to send it (I live in the U.S.) or possibilities for a home fix? Thanks for your helpful blog!


  5. Garry’s Camera replied back to my email inquiry. They do not make this repair to the Fujica AX-3, and after a few calls it’s become apparent that nobody will. The only thing left is to attempt a DIY fix, as I have nothing to lose at this point. While the rubber coating in the mirror box in my camera has oxidized, lightened and has cracks, it hasn’t yet started to peel. I believe attempting to remove it would quickly become a nightmare, so my thought is to perhaps come up with something to coat, stabilize and darken the rubber coating that is already there. If something works even for another year or two, I’d consider it a success.

    Liked by 1 person

    1. Thanks for updating with this, that’s really good to know about. My AX-3’s mirror foam was black and gummy but I’ve seen cameras with seals that have turned grey and cracked like you’re describing too. That’s a good idea about perhaps coating it in something. Best of luck!


  6. Hello Anthony.
    On occasion I have played Mr. Fix-It. Starting with throw away stuff like English made Diana cameras, bought 2 in Toronto Canada. $2 each. (Back in 78 that was $2:10 U.S.). Both came in original box with a no name roll of 120 film, expired 1973).
    The only old one with good seals…an original Zenit. Seals are black linen waxed thread used to stitch sails. .027inches dia. Available from any marine supply. However for what you want to try I suggest “Brush on Electrical tape” an air cure vinyl . Beauty is you can brush on multiple coats. Hope this saves your particular useable ‘antique’.”

    Liked by 1 person

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