Originally Posted by
inkista
I use the super-precision matte screen on my 5DMkII for my adapted Oly Zuiko OM 50/1.2. It does indeed help and is excellent and rendering more accurate DoF for the super-wide apertures.
Interchangeable focus screens started getting phased out when LCD overlays (for things like electronic levels and on/off grid lines, etc.) in the viewfinder started coming (first on Nikon then on Canon bodies). Given that an LCD overlay probably has to have power supplied to it, as well as signals to change what it's displaying, it may or may not be swappable, depending on how separate from the focus screen/delicate the overlay is.