The Schneider Kreuznach ND Centre Filter IV 82mm is a specialised, multi-coated neutral density gradient filter (darker in the centre, clear at the edges) designed to reduce light fall-off (vignetting) in large-format, ultra-wide-angle lenses such as:

Schneider-Kreuznach 90mm f/5.6 Super-Angulon

Schneider-Kreuznach 120mm f/8 Super-Angulon

Schneider-Kreuznach Super Symmar HM 120mm f/5.6

Schneider-Kreuznach Super Symmar HM 120mm f/5.6

Essential to avoid heavy vignetting with these lenses. Requires a 1.5-stop exposure increase and stops down the lens for best results.

No longer made, this is the last of the new sealed stock from Germany.