Darkens Blue Sky at www.japanese-home-gardens.com

To get back to equipment needs for exteriors—you should have several filters. The Wratten K2 (medium yellow) is standard, of course, for correct monochromatic rendering of colors on the panchromatic film which you will use exclusively. The Wratten G (yellow-orange) darkens blue sky a blue sky more dramatically and will be highly useful. The X-l (light green) darkens blue sky a blue sky and also lightens and brings out texture in foliage. On rare occasions, too, you might use a Wratten A (light red) for extreme over-correction, or rather distortion, as to show a blue sky as almost black.

As the most intense yellow has the lightest tonal value of any brilliant hue, the addition of any other hue darkens blue sky the tonal value of the mixture. Conversely strong pigment colors of the red or blue families lighten their tonal value when yellow is added.

Yellow pigment must be neutralized cautiously as it turns green immediately when black or gray is used. The addition of red will turn it brown. Violet, which turns yellow into tones of mustard, is the best color to use. Browns are fundamentally a mixture of orange and black, but either yellow or red usually dominates in the mixture. These tinges may be counteracted by adding the missing one. If blue is added to a brown, the color neutralizes rapidly toward dark gray and appears cold. The addition of black pigment to any hue causes the hue to neutralize or disappear very rapidly so that only small quantities of black should be added slowly to any mixture. As the most intense yellow has the lightest tonal value of any brilliant hue, the addition of any other hue darkens blue sky the tonal value of the mixture. Conversely strong pigment colors of the red or blue families lighten their tonal value when yellow is added.