For the canon eos 5d mkii digital slr camera the eg s focusing screen manual precision matte is designed for manual focusing with high speed lenses f28 or faster the ee s screen has finer microlenses than the ee a or eg d along with a steeper parabola of focus to make the image pop in and out of focus more vividly in the viewfinder however the eg s focusing screen is not recommended for slower lenses because its not very bright