Before rushing off to buy a split wedge screen make sure you can see the screen.
How is your eyesight? Do you use glasses? If so, for what correction, close, far, astigmatism?
I say this because the eyepiece of SLR's is set for a certain focus point. Usually 1 meter or -1 diopter. This allows a large number of younger people to use the camera without glasses even if they are slightly nearsighted. I'm not sure what Nikon chose for the FM, but -1 was common for several makes.
In the 1970's I sold cameras, mostly SLR's, and the most common cause of fuzzy pictures was missed focus. When a customer came back with this problem I would check if he could see the screen clearly. I would try a few diopter correction eyepieces, sometimes the improvement was dramatic. They just had not realized that they couldn't *quite* see the screen clearly and thus missed focus on some shots, especially when using the lens wide open.
You may have no problem with this but it is good to checkout first. Unfortunatly correction diopters have all but vanished since most all modern DSLR's have adjustable diopter built in for the eyepiece.
As an aside, I also am a big fan of plain matte with grid lines focusing screens. I have Olympus's version, the 1-10 in all my OM bodies.
About focusing wide angle lenses.
With a 28mm or wider just about anything over 10~12 feet you can scale focus, especially in good light with smaller apertures. With my 24mm lens outside in good light and over 10 feet I generally treat it as a fixed focus lens and leave it at infinity.
Last edited by pen s; 11-15-2013 at 08:28 AM. Click to view previous post history.