The Dorr White Balance Disk allows a manual white balance metering just by simply holding the disk in front of the lens. White balance often ruins photographs, with this easy disk, make your photos tonnes better looking! Ideal for outdoor and studio photography. When shooting portraits, skin tones are rendered naturally. For use with all cameras with a manually adjustable white balance. The dimensions of the white balance area is 85mm so is suitable for lenses with a thread up to that.