I have cleaned the glass on viewfinder and checked focus screen as well as
mirror. Than I went to the near by place. I visit very nice person who was
offering his F100 for sale.
I compare my viewfinder with his. I also had a chance to compare it with
Nikon D200 and Nikon F5 as he owns them all.
Result? Viewfinder of my F100 is perfect and I must admit the main reason
why I though it is bit cloudy, was simple dirt and greasy glass covering
viewfinder and probably also that I looked at it at night.
Comparing D200 viewfinder with F100 just insured me that my F100 has
bigger view (expected as different size of sensor/film) and is as clean if
not cleaner than D200. D200 has a bit higher contrast and feels to have
little warmer color cast.
Summary: I proofed myself that my F100 is perfectly in order. Also get
experience with Nikon Service and as last it showed me that I need to clean
the basics first and than start looking around. I am glad I was able to
compare my F100 to other one.
