For canon eos 1dmkiimkiinmkiii and eos 1dsmkiimkiii digital slr cameras the ec l focusing screen cross split image makes it easier for the user to get a clear focused picture using manual focusing the screen has a 3mm diameter split image spot for precise pinpoint focusing on subjects with distinct contours using the central split image rangefinder turn the focusing ring until the split image becomes a sharp clear complete and undivided image