Canon EG-S

EG-S, Focusing Screen (Super Precision) The Canon Eg-S Super Precision Matte Focusing Screen is an interchangeable focusing screen compatible with the Canon EOS 5D-Mark II camera. The Super Precision Matte screen improves the ease of focusing when doing manual focus, but is not recommended for use with lenses slower than f/2.8. With these slower lenses, the viewfinder will actually look darker than with the standard Eg-A screen.