an old Yellow 2 Filter
Toronto, In the days when orthochromatic black and white films were popular, filters were used to darken blue skies so clouds could be better seen in the negative and printed. Leitz had a wide range of yellow and green filters to fit various lenses and darken the blues. Otho film was blind to reds, etc so the various yellow and green filters were common,
These colours disappeared when panchromatic films and later colour negative films became common. Polarizing filters eliminated distracting reflections but were expensive. Blue and amber filters allowed indoor colour film to be used outdoors and vice versa while deep red filters made use of infra-red illumination in B&W films.
With today’s smart phones and digital cameras we seldom see filters.
