I have a selection of manual focus lenses for my Nikons which range from an original F with the prong linked FTn metering prism through an FE. Lenses that were not originally AI have been adapted to AI.
From what I have learned, none of them would have any practical use on a Nikon digitial SLR.
While this is a bummer on one hand, it does leave us able to select a digital SLR on merit rather than having to stick with the brand we have used for film these many years.
I can't speak about the D50, but if you can mount a lens on the D2x you can use it. There is even an option for entering the mm and f stop manually.
On my D1x, certain lenses can only be used in strict manual mode. In other words my telescope cannot use the metering system AT ALL. So I used the D1x manually. Setting the exposure and speed based on a handheld meter or by experience.
There are lenses that fit in-between. Yu can use SOME of the metering modes and not others. Go to:
And look up the parameters that the D50 requires. If in doubt, make a list of your lenses and ASK Nikon.