The Tiffen 138mm 85/0.9 ND Combination Filter blends both an amber color conversion 85 and a 0.9 neutral density filter. The ND filtration provides a 3 stop exposure reduction for darkening the entire image in order to photograph with a wider aperture or slower shutter speed than normally required. The 85 filtration covers the entire filter plane and converts the color temperature to 3400K for use with type A (tungsten) film.

This filter is made using ColorCore technology, a process that involves laminating the filter substrate between 2 pieces of optical glass, grinding flat to a tolerance of 1/10,000th of an inch, and then mounting to precision metal rings.