ZALA Single 45 Degree Split Image Focusing focus Screen For Hasselblad DSLR Camera Does not affect your camera's Lens ability.Easy to focus, especially with objects vertical lines Does not affect the accuracy of focusing. Does not affect the brightness of the screen. The focusing screen is a flat matte-finish translucent plastic with a split-circle in the middle, surrounded by a ring field of micro-prism. When the image is correctly focused, the circle becomes full and the line between will be unbroken. Otherwise, the line separates the circle into two halves.