Light seal problems on vintage Canon 7s RF

brianentz · Mar 13, 2025

I just got a Canon 7s in great shape but no trace of seals. I tried cutting and putting in new seals but the door becomes very difficult to open then. Very. Any tips? Am using 1mm camera seal material. I’m wondering if it’s a mistake putting seals in or maybe there’s someone I can send it to for this purpose.

film4Me · Mar 13, 2025

It may not have had seals from the factory, some don't, relying instead on the door edge lips to block the light. Cameras that do have seals for doors would necessarily need open cell sponge rubber of a type that doesn't give off any contaminating chemical gas. Seal sponge rubber sold as camera seals is generally the right rubber. Again, open cell sponge. Close cell sponge proves hard to compress for camera doors, as I found out with my Mamiya C3, a long door that wants to bend when lots of pressure is applied to it.

reddesert · Mar 13, 2025

I don't have a Canon 7s but I do have a Canon 7, which ought to be similar. Light seals should be applied as needed rather than as an article of faith. For the Canon 7, it has a U-shaped channel around three sides of the body opening into which the back door seats. These U channels are relatively unlikely to leak light. The place where the camera originally had a light seal and you should apply one is next to the back door hinge, which doesn't use a U channel because of the hinge. There is a flat spot maybe 3mm wide by the height of the door where you should put a seal. I think it goes on the body rather than on the door, but that may not be critical. Adhesive backed felt is a common material for that type of seal, and is what I used.

Ian C · Mar 13, 2025

A film door that gets stuck when opening after new seals are installed indicates that the seal material is too thick, too dense, or both. As others have said, it might also be the case that no seal is used in that particular location due to the design of the camera. Thus, there might be no seal clearance, causing the door to stick.

grain elevator · Mar 13, 2025

I put black yarn in my 7 as a seal, there's certainly enough space for that. I don't know for certain if it's strictly necessary but I think so, it doesn't seem a very tight fit without any seal. As others have said, your seal material is probably too thick or too stiff.

brianentz · Mar 13, 2025

reddesert said:
I don't have a Canon 7s but I do have a Canon 7, which ought to be similar. Light seals should be applied as needed rather than as an article of faith. For the Canon 7, it has a U-shaped channel around three sides of the body opening into which the back door seats. These U channels are relatively unlikely to leak light. The place where the camera originally had a light seal and you should apply one is next to the back door hinge, which doesn't use a U channel because of the hinge. There is a flat spot maybe 3mm wide by the height of the door where you should put a seal. I think it goes on the body rather than on the door, but that may not be critical. Adhesive backed felt is a common material for that type of seal, and is what I used.

Thank you. This is helpful and appreciated.

brianentz · Mar 13, 2025

Ian C said:
A film door that gets stuck when opening after new seals are installed indicates that the seal material is too thick, too dense, or both. As others have said, it might also be the case that no seal is used in that particular location due to the design of the camera. Thus, there might be no seal clearance, causing the door to stick.

Thank you. This is helpful and appreciated.

brianentz · Mar 13, 2025

grain elevator said:
I put black yarn in my 7 as a seal, there's certainly enough space for that. I don't know for certain if it's strictly necessary but I think so, it doesn't seem a very tight fit without any seal. As others have said, your seal material is probably too thick or too stiff.

Thank you. This is helpful and appreciated.

MattKing · Mar 13, 2025

Thread title tweaked

Light seal problems on vintage Canon 7s RF

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