DIY lights seals and mirror damper replacement (done on Canon FTb)

Discussion in 'Casual Photo Conversations' started by h_s|1, Jan 6, 2010.

  1. This is just a little report on my today's short project of replacing the light seals and mirror damper on my Canon FTb.
    Going over various web pages, I short listed the following materials:
    1. Foam to replace the mirror dampler. Readily available at craft hobby stores. The pack contained number of sheets, and some of them seemed to vary in thickness by an mm or two. I selected the one which seemed 2mm thick. $6 for a bunch of a number of sheets (this is in Montreal, Canada, btw).
    2. 100% pure wool. Some web pages recommend to get 8 ply, but all I got was Medium weight 4 ply black wool.
    3. Felt. Readily available at craft hobby stores.
    4. Adhesive. I used two: Lapage's Flexible plastic adhesive and Scotch's Quick Dry adhesive (this one is acid free). The former I used for the mirror damper and the latter for the back door seals. I was planning to use the former for all of these, but gave the latter a try just for the heck of it. People usually recommend rubber cement as an adhesive (not sure how it compares to these though).
    5. Naphtha (to clean away previous glue and decomposing foam).
    6. Tooth picks (to clean away previous foam).
    7. Ear buds (to apply naphtha).
    8. Box knife and scissors.
    Step 1:
    The most difficult step: to wet the previous foam with naphtha and to remove it. The more care was needed while removing the mirror damper for fear of damaging the focusing screen. The long seals on the back were relatively easier, and the felt foam near the winding crank side was so so (since I did it without removing the back door). How to clean these is explained on many web pages. Just make sure one does not use too much naphtha.
    Step 2:
    Install mirror damper. I cut a strip of foam that was round 2mm thick, 35mm wide and 3mm deep. Applied some plastic adhesive in small dots across the width of the base and placed the strip on it and pressed it a bit.
    Next, I also cleaned the lower edge of the mirror, which has all the decomposed gooey foam on it from the previous one. This was done by dabbing it with an ear bud doused in naphtha. In this step I also discovered that the mirror is quite tough. I had to brush the foam off with ear bugs and then cleaned that edge of the mirror with lens cleaner tissue (moistened with naphtha) followed by a final tissue cleaning. All this was done only on the few mm's where the older goo was sticking.
    Step 3:
    Cut a 5 mm wide by 5.1cm strip of felt and pasted this outside the hinge on the winding side. This was stuck using the quick-dry adhesive on strip's two ends only.
    Step 4.
    The thin ridges across the back were the last to be done. These were done by sticking a length of wool yarn across them. I just stuck one end of the wool first, then twisted it a bit to make it fit the ridge, and kept inserting it using a plastic coated paper clip and continued toward the other end. Reaching that end, I cut off the yarn at the appropriate length and pasted that end with the adhesive as well. The top ridge was a bit tricky, since this was done in two lengths to get a break at the place where the frame counter reset lever protrudes from the body.
    That is it, the camera's back door now springs back like new and all the goo is gone. I am very interested to see how wool behaves as time passes. Also, whether I will run in to some problems by pasting on only ends of wool and felt to the body and not their entire lengths.
    Plus, all this was done quite economically. Most of the stuff I already had in the house. All I needed was to get the foam and felt from the hobby store. Plus, with the material left over, one can do numerous number of cameras with it!
    I am also playing with the idea of pasting a strip of valour (or velvet) on top of the mirror damper. Wonder if this will make the mirror a bit quieter. If the foam can be replaced by felt, that might even be better (foam is kind of iffy given the way it degraded with time and environmental factors).
    I did not replace the four felt strip that are pasted on the door. They appear to be okay. I will shoot a roll and see whether are any problem.
    That is it, folks. Questions are welcome.
  2. Self-adhesive 1+2mm foam and felt does away with the glue and costs $1/8x10 sheet in Toronto. Not sure about old Canons but Nikons and others really only need a seal along the back hinge. Mirror bumper replacement is usually dead simple.The real pain, as you describe, is getting rid of the black guacamole. For many replacements, craft store foam is perfectly adequate--something the seal kit dealers will loudly deny. I've resealed Mamiya RB 67 Pro S backs and rotating adapters with this stuff with no problems.
  3. Yes, I suppose I could have looked for self adhesive foam. Since I was using foam only on the mirror damper, I just bought what I could find. That, and I could control where it actually sticks by placing my adhesive in a few dots across the damper mount.
    What I really liked was the idea of wool and felt, materials that won't turn in to go down the line. Apparently movie cameras use these materials. Also, velvet or velour for the strips on the back door.
    Last but not the least, the experience plus the satisfaction of getting a critical job done with mostly household stuff and at hardly any cost is worth the time. I spend a few hours on this, it was my first time, and I am sure that the time is going to be significantly less on my next camera sealing project.
    From this project, I was rather pleasantly surprised that the mirror in the camera is really tough. It withstood light scrubbing with ear buds and lens tissue. I started cleaning it with some trepidation and dread, but the outcome was magnificent. The mirror is now more or less 99% clean!
  4. HS, thanks for sharing this. I've done similar jobs on a number of cameras, like you I was a little nervous about the wool comimg away, so I usually glue it at a couple of extra places between the ends.
    Also being a lazy so-and-so I don't try to remove the sticky foam from the grooves, just run the wool over the top. Once the camera back is closed, it seems to compress the wool quite nicely and help keep it in position. I can see that in some cameras with thin grooves it might be too tight a squeeze, when removing the foam might be the better option.
  5. For most older Nikons, the foam in the channels along the length of the film door are really there more for dust/moisture protection rather than light blocking. Any light leaks I've ever fixed were at the hinge end(and rarely the clasp end)of the door. Someone other than a seal kit seller should do a PN tutorial video to show how easy this can be with readily available materials.
  6. John, Pete's post was one of the most illustrative that I found while researching this topic. In fact, his post made settle for wool; some have used cotton instead.
    Gary, yes I have read that too at some places. Now that I come to think of it, I should have put in a roll and tried to see how it goes without the thin and the hinge seals. Oh well, perhaps in the next camera.
  7. That looks a bit like overkill, John, but the card taped over the shutter will save some grief.
  8. Honestly look up Interslice on Ebay. He sells light seal and bumper replacement kits. It includes the materials you'd need for most film cameras and enough material to do a bunch. I've replaced the light seals in 4 OM-1 and 1 OM-2 camera with the kit I bought and it still has enough for at least as many cameras again. I think it ran $13 shipped at the time (about 2 years ago). Includes a useful little bamboo tools for getting the old light seal gunk out of the tracks. He has great instructions on his website for most stuff.
    Also I personally use denurtured alcohol then naptha for dissolving the old stuff. Works just great.
  9. I'm no survivalist, but $13 is a bit spendy for a little foam, some whittled popsicle stix, Q-tips, and a bit of handholding, especially given the range of online resources available.

Share This Page