TELEVISION  CAMERA  OPTICS LEARNING  OBJECTIVE:  Identify  the  optics of a television camera. You  were  introduced  to  the  functions  of  camera lenses  in  Chapter  11.  The  lenses  and  the  associated optics for television cameras (save viewfinder) operate in the same manner as still photography, but we will cover them briefly as they apply to the television medium. VIEWFINDER The  viewfinder  on  an  ENG  camera  is  a  relatively small television screen (1.5 inches in diameter), while a studio  camera  viewfinder  is  larger  (3  to  9  inches  in diameter).   They   both   produce   high   resolution black-and-white  images.  The  television  screen  on  an ENG camera is shielded from outside reflections by a flexible  rubber  eyepiece  that  adjusts  to  the  operator’s eye. In that rubber eyepiece, there is an adjustable lens for you to focus since the eye is placed within an inch or two of the screen. The studio viewfinder uses a hood to  shade  the  television  screen  from  overhead  studio lights. Within  the  ENG  camera  viewfinder,  there  are  a number  of  control  lights  or  displays  that  indicate  the status  of  certain  camera  functions.  Most  viewfinders automatically  display  information  on  tape  status,  battery condition,  tally/record  light  and  low-light  level indicator. The viewfinders display, on command, color bars,  patterns,  white/black  balance  setup  cursor  and camera  registration.  All  camera  viewfinders  are black-and-white. In some camera models you may use the viewfinder as a playback monitor for the VCR. The advantage of this feature is that you do not need additional equipment to  set  up  the  camera.  However,  some  video  camera manufacturers  are  discontinuing  this  feature  because today’s  cameras  are  more  reliable  and  recorders  have indicators to let you know when you are recording. LENS The lens selects a certain field of view and produces a small, clear optical image of this view. The lens and certain  attachments  are  sometimes  called  the  external optical system. When  you  work  with  video  camera  lenses,  you concern yourself with the following four areas: l  Focal  length l  Focus l  f/stop c  Depth  of  field Focal Length As you learned in Chapter 11, focal length is the distance from the optical center of the lens (which is not always its physical center) to the point where the image, as seen by the lens, is in focus. Portable   television   cameras   have   a   zoom,   or variable focal-length lens (fig. 14-8), that allows you to select  fields  of  view  at  different  distances  from  the camera  without  moving  the  camera.  It  allows  you  to change the focal length of the lens from long to short or from  short  to  long  in  one  continuous  operation.  A complicated series of lenses interact to keep the object in   focus   at   all   times   during   the   zooming   process. “Zooming in” is the gradual changing of the lens from a   wide-angle   lens   to   a   narrow-angle   lens.   On   the television  screen,  a  zoom  in  appears  as  though  the camera  is  moving  smoothly  toward  the  object. “Zooming  out”  is  the  changing  of  the  lens  from  a close-up  to  a  distant  shot  and  it  will  appear  that  the camera is moving away. The degree to which you can change the focal length of a zoom lens is the zoom range of your lens. The range is often given in a ratio, such as a 10:1 zoom range. This means  you  can  increase  your  focal  length  10  times. Some  cameras  have  a  “times  two  function,”  which allows you to double the focal length at any point in the zoom,  thus  making  the  maximum  20:1  for  the  above example. You  can  control  the  speed  of  your  zoom  either manually or by using a zoom servo. These features are covered in the following text. MANUAL  ZOOM  CONTROL.—   The  manual zoom control on ENG cameras is a small rod extending from the zoom ring. To zoom in or out, turn the zoom rod clockwise or counterclockwise. It takes some skill and  practice  to  accomplish  smooth  zooms  with  the manual control. ZOOM SERVO.— A zoom servo is nothing more than a small motor controlled by a lever. The distance the lever is depressed determines the speed of the zoom — typically from 2.5 to 20 seconds. The lever is called the  zoom  selection  or  T/W  switch  —  T  stands  for telephoto and W for wide angle. There  are  several  advantages  to  the  zoom  servo system. Zooms are steady and smooth, especially during slow zooms. The zoom control is easy to operate and allows you to concentrate more on picture composition and focusing. The zoom servo also frees the left hand to operate the manual focus and aperture controls. 14-6