Internal light seal? Maybe? ...

[dmr]

I'm here on day 3 of reincarnating a dead Mamiya SD, and actually starting the "put it all back together" phase, having discovered what really was making the thing malfunction.

Behind the shutter, and apparently once between the rearmost lens elements and the threaded brass focusing thing (helix?) there apparently once was some kind of foam or rubber or plastic seal or sponge of some kind. Remnants of it were both on the brass piece and on the lens assembly piece, and crumbs of it were all over the hollow space inside the brass thing.

My question is, how important is this? I really can't see any light path which something like this would seal The brass part is solid with the shutter assembly on one side and the rear lens element and a hood the shape of the image on the other side. I did a sanity check with the flashlight and can't see any light path.

Can this safely be left out?

If not, can I just seal this with that black silicone sealer stuff?

I saw references on "another network" to internal light seals around a "dome" but I'm not really sure if this applies in my case. I really don't know what this refers to.

Any advice will be appreciated. Thanks in advance, gang. 🙂

 

[kabkos]

I have safely left that particular foam lightseal out on several cameras and I have never had a lightleak because it was left out.

karl

 

[dmr]

I have safely left that particular foam lightseal out on several cameras and I have never had a lightleak because it was left out.

Thanks, Karl. That's good to hear. I'm sure it was in there for a reason, but I can't figure out what that is. 🙂 Maybe to suppress internal reflections off of the brass?

 

[dmr]

It's main purpose is to seal off the focusing helix from debris, that may enter from the film chamber.

Ok {>>BLINK<< lightbulb} now I get it, thanks.

Actually I removed quite a bit of debris from in there, that coming from the disintegrated old seal. 🙂