The Japanese blog Egami has uncovered a new Canon patent for a special coating on Neutral Density filters. The new coating is to minimize ghosting. Although Canon has a small number of filters out, mostly in the Super Telephoto lens arena, they have not gone into the filter business in a big way.
Patent Publication No. 2015-200805 (Google Translated)
- Published 2015.11.12
- Filing date 2014.4.9
- On the surface of the transparent substrate made of synthetic resin, deposited the inorganic hard film of fine uneven periodic structure
- The refractive index changes toward the surface layer side from the transparent substrate side