Replacing light seals

I have an old Olympus OM10 that needs new seals. It's not worth having a camera shop replace them, so I thought I'd try it myself. Amazon has light seal foam. What thickness should I use? They have 1.0 mm, 1.5 mm, 2.0 mm, 2.5 mm, and 3.0 mm. I'm guessing I should use 1.0 mm, but I'd like advice from you experts.

 

I thought I might prowl some thrift stores to see if they have any old rangefinder cameras. If I find one, it will undoubtedly need new seals. Will the same thickness I use for the OM10 be suitable for a vintage rangefinder?

It may cost a little more, but the kits make it much easier.

 

LINK http://aki-asahi.com/store/html/OM-10/foam/index.php

It may cost a little more, but the kits make it much easier.

 

LINK http://aki-asahi.com/store/html/OM-10/foam/index.php

I sent an email to him last week to see if those kits are still available, and never received an answer. I think it might be safer to get the foam from Amazon (and I can use it on the possible rangefinder(s)).

Easier yes, more accurate...possibly no. Different cameras use different thicknesses, some use different thicknesses in different areas, don't assume one size fits all. Having resealed about a dozen or so cameras, both SLR and rangefinders, over the years, I try to keep a supply of different thickness foam, black thick yarn, and felt handy. In my experience the mirror damper, and the area inside the door near the hinge of some cameras seems to be the areas of greatest variability.

Agree that the back hinge seal is the usual cause of light leaks on SLRs like your Oly. However, I've only ever used thin adhesive-backed craft store sheet foam for re-sealing. An Xacto knife and a metal straight edge help. Seal kits are usually overkill for most 35mm light leak problems.

c_watson | 1: What thickness?

 

The foam in the link in the OP is adhesive-backed.

 

SCL: What's the yarn for? I saw a page on replacing the seals on an OM10, and the guy says something about 'the string'; but he didn't mention it before, or what it was for.

I've just found this place that has an OM10 light seal kit.

 

USCamera Parts Downloads Plus | Olympus OM10 Custom Light Seal Kit

Stick a piece of ‘blu tack’ (sorry not sure what the US equivalent is, but that stuff students stick posters to the wall with) between a piece of grease-proof paper and stick it in the hinge. Close VERY gently so not to over stress the hinge, and you’ll get an idea of the thickness required. Door seal hinges can be cut to size with a scalpel from hobby shop foam sheets, and do not need adhesive, they’ll stay in under they’re own compression.

Some Japanese bodies have a groove in the camera body which basically surrounds the back except at the hinge, and there is a metal protrusion surrounding the door which fits into the groove when the door closes, but which benefits from packing to be light tight. The groove is usually very narrow so fitting such a narrow piece of foam without it twisting into that groove can be quite challenging. Lining the groove with the proper depth of yarn, which when compressed, provides the effective light seal. I usually place a couple of dabs of contact cement into a couple of strategic locations in the groove before inserting the yarn, which is stretched to compress it and then use a wooden skewer to pad it down. Closing the back fully compresses it and after a couple of days of compression it will stay compressed for years, yet be easily removable at a later date if desired.

Hm. I tried to contact USCamera using their web form, and it never completed. The last post on their Facebook page is 2016. I checked the State of Colorado Secretary of State, and their business license was renewed in 2017 and expires in 2020, so they appear to still be in business.

 

SCL: What kind of yarn? Just anything from a yarn store? What diameter?

I use ordinary black knitting wool for the film door grooves, secured with silicone glue, and sticky back black felt for the hinge seal and mirror bumper. Wool is nicely compressible and sinks snugly into the groove when the back is closed and pressed together. It's important not to block the little frame counter reset lever, invariably found to the right of the upper groove, With the hinge seal I scrape off the old foam and replace it with one layer of felt, then close the back and feel for tension compressing the felt. If there's no tension the felt is too thin so I apply a second piece of felt to the opposite surface.

As John said - (black) wool yarn. Yarn isn't sold by diameter, it is stranded, so you can separate the strands to get whatever diameter you want.

Looking at the camera, it seems pretty straightforward. SCL says that fitting a narrow piece of foam in the grooves can be challenging. I think I could make the foam fit with some patience. If not, the yarn sounds like an easier solution.

 

If I am unable to find a pre-cut kit, I think cutting stringers for flying balsa airplanes in my youth may stand me in good stead cutting foam from sheets. The larger piece of foam on the right side of the camera looks pretty thin. I'm estimating a 1mm thick piece would be in order. But what about the grooves? I don't want to spend ten bucks on a sheet of 1mm foam, only to find it's too thin for the grooves. Can anyone suggest how thick the foam in the grooves should be?

 

I have a question about the top groove and the counter reset lever. John Seaman says it's important not to block it. I assume the foam goes into the groove up to the left of that position, and a smaller piece goes to the right of it? Any worries about not having a seal over that couple/few millimetres?

 

But my main question is the thickness of the foam.

Yes you have to leave as small a gap as possible either side of the counter resetting lever, making sure it still moves freely. I've done loads like this and never had a problem with light leaks. I don't use foam so I can't answer about the thickness. Different people have different ways of doing the job, it's a case of finding out what works for you with the materials you have available.

 

By the way, by using wool I don't find it necessary to scrape the old foam out of the grooves, just check for and remove any bits of grit, film etc. The old sticky foam just helps to keep the wool in place.

Edited May 4, 2019 by John Seaman

That tongue and groove-like channel along the back really doesn't require foam or yarn. Yarn can make things too snug and require too much pressure to close the back. Original seal material in Nikon FE/FM variant bodies' backs was very thin strips large-ish cell foam, thinner than any of us could cut. Always thought they were more a protection against dust and moisture than light. I simply cleaned it out and never worried about it again--or suffered any light leaks traceable there. The interference fit between back and body obviously did the trick. The hinge seal is critical. I'd get 2-2.5mm+ foam and skip the skinny stuff. A bit thicker isn't an issue since it needs to compress to keep out light at the hinge. I find the buck or so/sheet craft store sticky-back foam to be near-perfect.

I agree that some cameras, particularly those made to close tolerances are probably OK without film door seals. The problem is when selling them you need to be 100% sure there will be no light leaks, which is why I invariably replace them. And some makes use a lot more foam than Nikons, around the inside of the film door itself as well as in the grooves, no doubt for a good reason.

The problem is when selling them...

 

Wait... what? People sell their cameras? :eek:

I've replace the seals in a few cameras and usually I'm able to find the thickness listed some place on-line. I've used the kits too.

 

To cut the foam, use a sharp exacto knife and hard straight edge. With the narrow channels, cut the strip really thin, - thinner than you think. You don't want the adhesive back sticking to the side of the channel and getting twisted.

 

Something that really helps a lot which I learned from one of the kits is to liberally apply hand sanitizer (like Purell) to the adhesive back. This lets you reposition the foam as needed. It evaporates overnight and then your seals are stuck where they are supposed to be.

The hinge seal is critical. I'd get 2-2.5mm+ foam and skip the skinny stuff. A bit thicker isn't an issue since it needs to compress to keep out light at the hinge. I find the buck or so/sheet craft store sticky-back foam to be near-perfect.

 

Maybe I'll swing by Michael's this weekend. The foam from Amazon costs a sawbuck. I'll try the 2.0mm and/or 2.5mm stuff.

It's been about 7 years - but has anyone sent an email to Jon Goodman at jon_goodman@yahoo.com to see if he still sells a complete, pre-cut kit?

Maybe I'll swing by Michael's this weekend. The foam from Amazon costs a sawbuck. I'll try the 2.0mm and/or 2.5mm stuff.

 

If you're successful at Michael's, please post back with what you obtained and exactly what they call it. In NYC, the staff at every Michael's I've tried acts like I'm out of my mind to think they would even sell such a thing. In all the years people have recommended buying adhesive-backed foam, velvet or felt in a craft/hobby shop, I've yet to find one that carries the stuff.