3. The warm colors are at the top of the horizontal axis. The cool colors are at the bottom. Table 3-5.–Neutral Density Filters 4.   Filters   of   the   same   color   are   added   and subtracted   normally: 30M + 20M= 50M 10B  -  05B  =  05B 5.When two filters of different colors and equal densities are combined, the color of the combined filters changes, but the peak density remains the same. 10M + 10C = 10B 10R + 10G = 10Y 6. A filter combination having all three primary colors creates neutral density. To correct this neutral density, subtract the lowest density from each color. 10R   +   20G   +   30B Density .10 .20 .30 .40 .50 .60 .70 .80 .90 1.00 -10 -10 -10 0R  +  10C  +  20B  (Results) amount of exposure reduction provided, are shown in table  3-5. SPECIAL-PURPOSE FILTERS Special-purpose  filters  for  use  with  black-and-white film are those filters not classified specifically as contrast or correction filters. Some of the special- purpose filters can be used with both black-and-white and color film. Two of these special-purpose filters are intended primarily for use with color film. When you desire to reduce the depth of field but maintain a given shutter speed, ND filters permit the use of a larger f/stop which in turn, reduces the depth of field.  Neutral  density  filters  are  used  extensively  in motion-picture  photography  where  depth  of  field  is usually quite deep. ND filters are also used with mirror type of lenses where there is no aperture control. NEUTRAL  DENSITY  FILTERS HAZE  FILTERS Neutral density (ND) filters reduce the amount of light passing through a camera lens without changing the reproduction of colors in the scene. These filters are nonselective in their absorption of colors of light and therefore  uniformly  reduce  the  various  colors  of  light  in the spectrum. Thus white light and colored light are transmitted  through  an  ND  filter  with  only  the  intensity of the light being affected. These filters can be used with both black-and-white and color film. Neutral density filters are gray in appearance. These filters may be needed for pictures being made of a brilliant subject in bright sunlight. When you have set the fastest shutter speed and the smallest f/stop and still cannot make the picture without overexposing the film, you can use an ND filter to further reduce the exposure. Neutral density filters manufactured by Kodak are called Wratten Neutral Density Filters and are available in several densities. The ten most popular densities, with the Suspended  in  the  earth's  atmosphere  are  minute particles  of  vapor  and  dust  that  cause  a  veil-like appearance called haze. This haze is most apparent in distant scenes. Haze is the result of sunlight being scattered by minute particles of matter that are present in  the  air.  The  amount  of  haze  can  vary  due  to atmospheric conditions. Haze should not be confused with mist, fog, smog, smoke, or clouds. These con- ditions  can  also  produce  a  veil-like  appearance,  but filters  have  no  effect. When sunlight is scattered, both green light and red light are also scattered by the ever-present haze, but not nearly  as  much  as  ultraviolet  radiation,  violet,  and  blue light. When filters are used to absorb scattered sunlight, penetration of the haze is possible. A haze filter is any filter  that  absorbs  atmospherically  scattered  sunlight.  A Exposure reduced by  f/stops 1/3 2/3 1 1 1/3 12/3 2 2 1/3 2 2/3 3 3 1/3 3-7