The surface of Cokin's colorless duffision filters are slightly granulated, diffusing strong light without affecting the clarity of the image. They are recommended for lenses up to 135mm in focal length. Ideal for portraits because the effect eliminates small skin blemishes while softening facial contrast & wrinkles. They are available four grades. · Diffuser Light (820) is the gentlest effect. · Diffuser 1 (830) for mild effect. · Diffuser 2 (840) for medium effect. · Diffuser 3 (850) for strongely diffused portraits