Tiffen Filter Wheel 3 Black Diffusion/FX Filter, 2 Density

Black Diffusion/FX, is a distinctive yet simple diffusion filter, as it is refined in its ability to reduce fine sharp detail and produce a minimal effect on bounced and reduced highlights. The Black Diffusion/FX look, is apparent by its seemingly non-destructive effect, meaning that any reduction in color saturation is kept to a minimum. When used on close ups, facial features, such as eyes and hair remain sharp on the focal plane while finer and unwanted skin detail smoothly blends away.

Black Diffusion is kept in check by what is embedded in the filter, performing the jewel role in controlling the optical softening element form overly blurring specular highlights, which might otherwise cause stronger halation.