The mildest of the contrast filters for black and white photography, yellows produce the most natural tonal range.
By absorbing ultra-violet, violet and blue it moderatly increases contrast in sky, foliage and architecture photography.
It's natural tone reproduction in landscapes, cityscapes and portraits make very it useful for all daylight exposures.
The yellow family also includes the yellow 'minus' blue filter (yellow #12). This filter cuts haze in aerial exposures and reduces the excess blue in full moon astrophotography. It is recommended as the standard filter for use with Kodak Aero Ektachrome Infrared film.
Available in most sizes in medium #8(standard)and Dark #15 as well as yellow 'minus' blue #12.