Originally posted by johnc ...
It is very well worth ensuring you have the shim adjusted correctly. Initially, I was content with the very slight error I experienced with the Pentax shim, and didn't want to run the risk of scratching the screen or introducing dust while experimenting with shims. But with the f1.2 lenses, every mm counts and once adjusted correctly, you'll be glad you did.
In short, if you have this type of MF, wide aperture lens - the screen is worth it's weight in gold IMHO.
+1
I can really recommend the screen also, I did get the one that has AF lines on it and I find that they can be quite useful, as a compositional aid but they can also be used to check that the horizon is level or for vertical lines if there is no horizon in sight. The lines are very transparent and don't interfere at all.
P.S. I also use the TENPA 1.36x eyepiece which makes for a great combo, especially with wide angle lenses when you want to focus manually. It can be hard to see the entire frame though so I sometimes take it off when I don't need the magnification.