Color sensitivity of the film Filters  available Black-and-White Line Originals A black-and-white line original has no middle or intermediate tones between the lines and background. Therefore, the best film for copying black-and-white line originals is one with extreme contrast, such as Kodak Kodalith film. These films produce high contrast and  extremely  high  density  with  an  absence  of  fog, which ensures clear lines on a dense background. Kodalith type of films have a very limited exposure latitude,  and  therefore,  must  be  given  very  accurate exposure.   Underexposure   produces   low-contrast negatives  that  result  in  prints  having  a  muddy  gray background  instead  of  a  clear,  crisp,  white  background. Overexposure causes weak or very fine lines to fill in and results in a less than perfect transparency of the lines on the negative. Typewritten material should be included in this type of original. When an original is typed or printed on thin white paper and on one side only, you should place another sheet of white paper behind the original to copy it. This increases the reflective ability of the original and increases contrast. When the original is printed or typed on both sides of thin white paper, place black paper behind the original to help prevent the printing or type on the reverse side of the original from showing through. Colored  Line  Originals In   copying   colored   line   originals   to   a black-and-white  reproduction,  you  must  maintain  the high contrast between the lines and the background. This is best achieved by using a high-contrast panchromatic film, such as Kodak Contrast Process Pan film and a filter. When the lines or subject is to be rendered light against a dark background, the filter should transmit the color  of  the  subject  and  absorb  the  color  of  the background. When the subject is to be rendered dark against a light background, the filter should absorb the color of the subject and pass the color of the background. For example, a blueprint has white lines on a blue background. Copying the blueprint with Kodalith Pan film without a filter cannot produce maximum contrast because the film is highly sensitive to blue light and thus records the image of the blue background as a midtone of gray while recording the white line image as a dense highlight. When a red filter is used, the white lines still record as a dense highlight on the negative, but now the 8-11 blue background records as a shadow area because the red filter absorbs the blue light reflected from the blue background.  Thus  the  background  reproduces  darker when a red filter is used. Black-and-White   Continuous-Tone   Originals To   reproduce   the   tone   gradation   of   a continuous-tone  original,  you  must  use  a  long-scale film. As discussed previously, a commercial type of film, such as Kodak Commercial film, is recommended. The common fault in continuous-tone original copying  is  underexposure  and  overdevelopment.  Full exposure with restrained development is the best rule for this type of work Although appearing as line originals, handwritten material, pencil drawings, and so forth, are actually continuous-tone  originals  because  of  the  midtones  they contain.  These  should  be  copied  as  continuous-tone originals.  Films,  such  as  Kodak  Professional  Copy  film or Kodak Commercial film, are recommended. Colored  Originals When   a   black-and-white   reproduction   of multicolored   reflection   originals,   such   as   color photographs, oil paintings, and so forth, is to be made, it   should   be   copied   with   a   moderate   contrast, panchromatic film capable of recording numerous shades  of  gray.  Panchromatic,  long-scale  film  is recommended  for  copying  this  type  of  color  original. Colored originals are almost limitless in their degree of difference because of all the possible colors and hues. Each  different  colored  original  should  be  copied  on  the basis  of  what  is  desired  in  the  black-and-white reproduction. Color  Reproduction  of  Color  Originals Selecting a film for copying colored reflection originals to make color reproductions is a matter of what type   of   reproduction   is   needed-reflection   or transparency. Films, such as Kodak Vericolor III Professional Film Type L and Type S and Vericolor Internegative Film, can be used to produce color reflection  copies.  Color  transparency  film  must  be  used to  produce  color  transparencies  from  reflection originals. Some films have a different recommended ISO rating when used with tungsten or daylight light sources. Be sure to consult the data sheet supplied with the film or the Photo-Lab Index to determine the proper ISO  setting.