Dirty Focusing Screen

I recently acquired an AT-1 body that has dirt on the inside of the focusing screen (on the prism side). You can see it with or without a lens. It's not very obvious in every day casual use. The dirt (smear) is not loose. The fact that it's there at all is annoying. Is there some way to clean this? It would involve removing the screen.

If the dirt is between the screen and the prism, taking off the top plate and removing the prism is one way of cleaning away the dirt. I've never tired this on an A-series camera, but did clean dust off the top of the screen of a Canon FX once by doing this. If you've never tried this before, look for a video on YouTube on how to take the top plate off an AT-1, or AE-1. More electronics in a A-series camera, so probably harder than a F-series camera.

There's no way I'm taking the top off of that camera. If that is the only solution, I'll live with the dust. I'm wondering how in the world it got in there in the first place.

I had that problem when I first started 35mm with my own camera.

I took it into a tech a couple of times, and finally gave up, it was just going to get something inside again, and I could not stop it from happening.

 

I think the dust/dirt got in the body when I changed lenses, then got around the sides of the focusing screen to the top of the focusing screen.

Even if you take the top off, there's probably a lot more dismantling to do to get at the screen. As you have rightly decided, the dust is best ignored.

 

A big advantage of cameras like the AE1-Program is that the screen can be removed from below.

Leave alone. Live with it.

I recently acquired an AT-1 body that has dirt on the inside of the focusing screen (on the prism side)…

Old deteriorating foam used around the prism often finds its way onto the focusing screen in old SLRs. If you can’t remove the screen from the front and if not comfortable with a deep dive, best let it be.

Singing words of wisdom, let it be...

Singing words of wisdom, let it be...

Or should that be "speaking words of wisdom". Sorry just a Beatles pedant here!

That camera makes really great images and is fun to use but I have too many cameras. When I grab a 35mm it is almost always the A-1 or the Mamiya 645E. Medium format has become my new love. The AT-1 and two other Canons are for sale in the classified section of photo.net. I just went a little too crazy buying cameras early this year and last. Some kids just never grow up.

If the foam and seals are deteriorating, this is a job you can do yourself with good quality foam, adhesive and a craft knife.

gwhitegeog:

Thank you for the help but the offending dirt is on the inside of the prism which is only accessible by removing the top of the camera. That's not a job that I am willing to tackle.