In article <4ghmi6$1mu0@power.ci.uv.es>, Alex@uv.es says...

>I have a Nikon F3 which a Tamron 28-200 (f3.8-5.6) lens. My problem is
>the "focus-screen" (K type), it is very dark for the lens in 200mm >(f5.6) position. I find a focus-screen which "split-image" and higher >lightness (high luminosity).
>What is the best type?. Wich a new "focus-screen" very lightness, I be
>have problems whith another lens f2?. How many types of focus-screen
>"which diferent lightness" have Nikon?.
>Thanks and sorry my bud english.

You may need to go to a different source than Nikon for a brighter screen that still has a split-image rf - maybe Beattie. If you use
a faster lens with the Beattie, you may have difficulty focusing
on the matte surface part of the screen, and wide-angles will look
dark at the edges in the viewfinder. Nikon may have a split-image
screen designed to work with slow lenses without blacking out one
side (moving your eye around to center it on the eyepiece helps),
but I am not sure if they do. An F4 screen is a bit brighter than
the F3 screens (especially if there is no red dot on the edge of
your F3 screen frame), and will fit the F3.
Hope This Helps