How to replace the light seals of your analogue camera

The following video (in English, with German subtitles) shows the process in detail:

 

If you own one or more analog cameras, chances are high that one or all of them will need their light seals replaced.

These small foam strips break down over time and can cause light leaks that can ruin your photos completely in the worst case. In any case, image quality suffers, and the vast majority of cameras available on the used market (especially from private sellers) are sold with defective light seals.

 
If the seller doesn’t explicitly say otherwise, you can assume a camera with defective light seals is being sold.

Photo: So-called light leaks caused by defective light seals

The replacement takes some time, patience, and nerves, but it’s also doable by amateurs on a quiet afternoon. In this guide, I’ll show you step by step how to replace the light seals—just like we used to do in our small camera workshop. We sealed hundreds, if not thousands, of cameras this way, and it always worked reliably.

What you need

• Pre-made light seal kit or foam pads in various thicknesses for cutting to size
  • Usually you need a 1 mm thick pad for the seals on the back cover (cut strips about 1.5 mm wide)
  • and a 2 mm thick pad for the mirror stop damper
• Utility knife, ruler, and cutting mat (for DIY cutters)
• Cotton swabs
• Isopropanol (for removing the old seals)
• Wooden toothpicks or bamboo sticks for scraping out the old seals (gentler on the camera finish than metal tools)
• Tweezers for precisely positioning the new seals
• Painter’s tape (to protect the shutter during cleaning)
• Microfiber cloth and toothbrush (for the final cleaning)

In our ready-made light seal kit you get everything you need for the replacement except the solvent (isopropanol), including a special tweezers with an integrated scraper for stubborn seal residues.

Photo: Contents of our Ausgeknipst light seal kit with pre-cut light seals in various thicknesses and widths, cotton swabs, hot shoe cover (available as a bonus in Feb 2025) & special tweezers.

Which cameras is this guide suitable for?

The process is almost identical for most 35mm SLRs, e.g., Canon AE-1, Olympus OM-1, Pentax ME, or Minolta SRT series.

Step 1: Remove the old light seals

Before you start:

• Carefully tape off the delicate camera shutter (the curtains in the middle of the camera body) with painter’s tape so no old seal residue falls into the mechanism. The shutter curtain is paper-thin and extremely sensitive—never touch it with your fingers or tools.
• Tip: On almost all cameras mentioned here (Canon AE-1, Olympus OM-1, Pentax ME), the back can be removed without tools: Pull the small spring-loaded pin on the hinge down, and the door will come off. Working on a removed back is much easier and also protects the shutter.

You’ll usually find the old seals here:

• At the top and bottom edges of the back door

• Around the hinge of the back door

• At the mirror stop damper (not a real seal, but should be replaced often)

Here’s how to remove the old seals:

1. Apply isopropanol to the old seals with a cotton swab.

Photo: Old seals can be dissolved with some isopropanol and then removed more easily.

2. Wait a moment for the material to soften, then gently scrape it out with tweezers or a wooden toothpick. Avoid sharp metal tools directly in the grooves—they can scratch the camera’s paint, causing unwanted reflections later.

Photo: Use the back end of our tweezers to carefully scrape away the old seals. Don’t apply too much pressure, or you might damage your camera’s paint.

3. Make sure no residue falls inside the camera.

Photo: If old sealing material falls inside the camera, hold the camera with the opening facing down and gently brush it out with a soft brush. A blower can push sticky particles deeper into the mechanism or mirror box. Sometimes gently tapping the camera from behind helps too. Be careful: like with a baby who’s choking ;)

4. Finally, remove the last particles with a cotton swab soaked in isopropanol 

Photo: To remove the last bits of old light seals, tear off a piece of cotton from a cotton swab with your fingers, clamp it in tweezers, and dip it in isopropanol. Then run the soaked cotton along the seal groove until the cotton stays completely white. The more thorough you are here, the better the new seals will stick later.

 

Photo: Removing the brittle mirror stop damper on a Pentax ME Super

Tipp: Be especially careful when removing the upper and lower door seals. No alcohol should get into the film counter mechanism (usually top right on the back) as it could damage the mechanism.

Photo: Most cameras have a small opening here for the automatic film counter reset. No old sealing material should get in here, as it could block the mechanism. 

Step 2: Install the new light seals

After cleaning, you can install the new seals:

1. If you use foam sheets, cut the strips exactly to the needed size.
2. For pre-made adhesive seals, peel off the protective film in stages (only 2-3 cm at a time), not all at once. This prevents the exposed glue from sticking to the tweezers or the wrong spots.
3. Press the strips into the right position with tweezers.
4. Make sure the seal fits well at the hinge and the door still closes easily.

Photo: New light seals are best positioned precisely with tweezers.

The trickiest part is the thin seals along the back door grooves. If they twist, just stay calm and press them into the groove with tweezers. These self-adhesive strips are a bit fiddly to position, but you don’t need to buy any special glue.

Pro tip (Isopropanol trick): Lightly moisten the adhesive side of the self-adhesive seal with isopropanol. The glue loses its stickiness for about 1-2 minutes, allowing you to slide and adjust the strip smoothly into the narrow grooves. Once the alcohol evaporates, the glue holds firmly.

Glue-free alternative: If the glue method causes problems in very narrow grooves, you can leave the protective film on completely and simply press the strip into the groove without glue. The friction in the tight groove holds the foam securely in place without adhesive.

Step 3: Replace the mirror stop damper

1. Find the old mirror stop damper (usually a foam strip above the mirror).
2. Remove it carefully so no particles fall into the mirror box.
3. Cut the new damper to the appropriate size.
4. Use tweezers to place it exactly in the right spot.
   
   

Photo: Installing the new mirror stop damper

Community tip: Before removing the old damper, cut a small piece of Post-It and place it over the mirror and focusing screen before you start scraping. This way, no sticky crumbs fall onto the delicate surfaces.

Important: Do not get alcohol on the focusing screen! It can be permanently damaged.

Step 4: Final cleaning and inspection

• Carefully peel the painter’s tape off the shutter curtain.
• If you removed the back panel, reattach it now.
• Close the back door and check that all seals are properly seated.
  
  

Photo: Finally, clean the outer casing with a slightly damp microfiber cloth and a drop of dish soap. Avoid wet brushes — water must not get into housing gaps or the electronics.

 

Conclusion

Done! Your camera now has new light seals and should work perfectly again – goodbye light leaks!

This guide is designed for 35mm SLRs but can also be applied to medium format cameras or film cassettes with minor adjustments.

If you have any questions, feel free to leave me a comment or send us a message via the contact form in our online shop :) I’m looking forward to photos of freshly serviced cameras!

 

Have fun taking photos and best regards, your Vladi!