In article <19961115220200.RAA00474@ladder01.news.aol.com>, onedon@aol.com says...

>Help with fogged Nikon mirror!!!
>I recently purchased a used Nikon FA. I was warned prior to the purchase
>that the mirror had a slight fog that was barely noticeable. When I
>called Nikon they said there was no recomendation for cleaning it and that
>it should be sent in for repair. My local shop said that the fog was
>probably in the glass and could not be cleaned. I would like to avoid
>sending it to Nikon if possible.
>Is this a problem I should attempt to fix and if so do I have to replace
>the mirror? or can I just take a cloth to the mirror and not worry?

I would not take a cloth to it, but I would attempt a cleaning if
the fog is sufficient to reduce VF contrast, and you are OK with
the slight risk of causing one or two hairline scratches in the
front-silvered mirror surface (optically unimportant) - and especially
if the mirror is unuseably bad, and the alternative is replacement
anyway. If you wish to proceed with cleaning, this is how I do it:
- wash hands in dishwashing detergent to remove oils
- gently breath up onto the mirror (to minimize spit marks)
- LIGHTLY, while rotating it, swirl a fresh Q-Tip over a
limited area of the breath-fogged mirror surface
- repeat, with fresh Q-Tips, until the whole surface is clean
(you may not need to go over the whole surface)
- if an area remains dirty, spray a slight amount of a
commercial glass cleaner, like Windex, onto a clean Q-Tip,
after which, clean the area again using breath
- remove the viewing screen, blow off the under side of the prism
gently, using a large hand air syringe, being careful not to
touch the mirror surface
- blow off the viewing screen, and replace it in the camera (do
not blow into the VF after this, or dust will be forced above
the screen, requiring removal of the screen to eliminate it)
I would look carefully at the FA mirror first to see if you can
tell what the fog is caused by - if it was fogged from improper
cleaning, further cleaning may not help if the mirror surface
has been abraded (as by having been rubbed with a cloth...).
Hope This Helps