Abstract: A soft edge mask comprises a panel having an opaque area forming a mask portion and defined by a clearly focussed edge of a predetermined shape, a transparent area forming a clear portion defined by a clearly focussed edge of the same said predetermined shape, and a margin portion extending between the opaque portion and the clear portion, the margin portion having a light transmissability varying progressively from the edge of the mask portion to the edge of the clear portion, and, at each position between the mask portion and the clear portion, being clearly focussed and having the same said predetermined shape.