Fixing the prism

[oriecat]

There is a very large smudge like thing on the prism on my new to me Mamiya/Sekor 500DTL. I have tried gently cleaning it and nothing changes. I wasn't sure how much I should be fooling with it, I don't want to damage anything... another option I just thought of would be swapping out the prism from one of my 500TLs with broken light meters. I've taken one of them partially apart already, but I didn't really look at the prism to see how it is in there. Is that doable? Other thoughts? I know the smudge doesn't affect the photos, but it's really annoying, it takes up almost 1/3 of the viewfinder...

 

[Mitica100]

There is a very large smudge like thing on the prism on my new to me Mamiya/Sekor 500DTL. I have tried gently cleaning it and nothing changes. I wasn't sure how much I should be fooling with it, I don't want to damage anything... another option I just thought of would be swapping out the prism from one of my 500TLs with broken light meters. I've taken one of them partially apart already, but I didn't really look at the prism to see how it is in there. Is that doable? Other thoughts? I know the smudge doesn't affect the photos, but it's really annoying, it takes up almost 1/3 of the viewfinder...

I would definitely swap the prisms. And then I'd try to clean the one dirty to see if it goes away.

I'm not familiar with the Mamiya SLRs but most prisms were made out of optical glass. I think you'd be ok with trying to gently wipe the smudge from the prism, by using a Q tip wrapped in lens cleaning tissue and dipped in 90% alcohol (make sure to squeeze the excess of alcohol). Then wipe the prism quickly but gently with dry lens cleaning tissue.

One question comes to mind, do you know how and when the smudge got there?

 

[oriecat]

No, I don't. It was on there when I got it, it was a holiday gift. Thanks for your thoughts Mitica!! I will see what I can do.