scope:

This standard is issued to describe a general method of describing filters according to construction type, optical quality, and intended use, and to establish uniform definitions, general requirements (which includes the military filter designation system), detailed requirements, and test methods for filters used in military photographic work.

This standard covers photographic light filters classified as to the material from which they are constructed (type); as to optical quality (grade); and as to intended use (class).

Filters are typed according to the material from which they are constructed.

Type I - Polymer sheet or film. Type II - Polymer layer sandwiched between two sheets of glass. Type III - Solid glass. Type IV - Materials other than those used for types I, II, and III.

Filters are graded according to optical quality.

Grade B - High optical quality - to be used in the path of image-forming rays. Grade C - Lower optical quality - not to be used in the path of image-forming rays.

Filters are classed according to intended use.

Class B - Used with black and white film. Class C - Used with color film. Class P - Printing (color or black and white). Class Z - Light polarizing (color or black and white photography). Class S - Photographic safelights. Class ND - Neutral density to cut down light uniformly across the spectrum (color or black and white photography).