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Figure 12-5.On-easel color analyzer
Making Transparencies from Color Negatives

Photography (Basic) - Introduction to photography and other graphic techniques
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corrections are then sent through a translator device to the printer. This system has essentially been replaced with electronic darkrooms at Navy imaging facilities. On-Easel  Analyzers An  on-easel  color  analyzer  (fig.  12-5)  is  an electronic photometer used to measure the illumination and three color primaries of light on the baseboard of the   enlarger.   These   photometers   take   these measurements through tricolor filters. On-easel measurements are made conveniently by placing a small probe on the reference area of the projected image on the baseboard. This small probe is connected to a fiber-optic light tube that carries the light from the reference area to the body of the photometer. Color  analyzers  are  programmed  using  standard negatives  printed  by  the  trial-and-error  method  of  color printing. Once a good color print is made from the standard negative, the image luminance of the master negative is measured from the reference area. This reference area is read through red, green, and blue tricolor filtered sensors and finally without filters over the photocell. The analyzer scale is then zeroed for each condition.  You  then  insert  the  new  production  negative in  the  enlarger  and  place  the  photocell  on  the  same projected reference area on the easel. The aperture and dichroic filters are then changed until the meter is zeroed out once again. Most on-easel color analyzers have a number of memory  channels  so  you  can  store  programs  for different film or paper types. The advantage of on-easel color analyzers is that, unlike   off-easel   evaluation,   each   measurement compensates  for  filter  fading,  lamp  aging,  and  different image  magnifications.  Exposure  and  filtration  are  given directly. A disadvantage is that the readings must be made under the same conditions as color printing on an enlarger  (complete  darkness  except  for  the  illumination of the projected image of the enlarger). Both on-easel and  off-easel  evaluation  depend  strongly  on  accurate readings and placement and choice of a good reference area. Two   methods   of   electronically   aided   color evaluation  are  used.  They  are  spot  or  small-area measurements and large-area or integrated measure- ments. Small-area measurements made on the easel are the most accurate; however, a small-reference area is not always  possible. When  small-reference  areas  are  not  provided, large-area measurements can be taken. Large-area measurements  are  made  usually  from  the  whole negative   area.   For   off-easel   evaluation   using   a Courtesty of Kreonite Inc. 302.262X Figure 12-6.–Kreonite color processor, Model KCP-16. densitometer,  a  large  photocell  is  used  to  take  such readings. For on-easel analyzers, the image is integrated by  placing  diffusion  material  between  the  negative  and the  photocell.  You  then  place  the  photocell  and  sample various areas of the projected image. These sample areas are then “‘integrated” to gray as though they were a typical  subject.  This  type  of  evaluation  does  not compensate for images that do not contain typical color or tonal distributions; for example, when the subject of a negative is predominantly red, an integrated reading overcompensates and a cyan print results. That is called subject anomaly or subject failure. This is the method used by many automatic printers. Color prints, such as these,  must  be  color  corrected  manually. COLOR PRINT PROCESSING Color printing paper must be handled and processed in complete darkness because color paper is panchro- matic.  Like  color  film,  time  and  solution  temperature  is much  more  critical  than  in  black-and-white  processing. Because the processing of color paper must be very consistent, color prints are not processed in trays. Color paper is always processed in automatic color print processors (fig. 12-6) or rotary drum processors. 12-13







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