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Television Camera Optics
The Television Studio Production Team

Journalist 3 & 2 - Introduction to Journalism and other reporting practices
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Figure 14-8.—Zoom lens. You  must  be  aware  of  two  disadvantages  of  the zoom servo. Although relatively quiet, some zoom servo motors emit  a  humming  noise  that  is  picked  up  by  the camera-mounted  microphone.  Additionally,  the  motor uses power provided by the camera battery. FOCUS   CONTROL.—    The    focus    control    is usually  a  rubber-covered  ring  on  the  zoom  lens.  To operate it, you rotate the focus ring either clockwise or counterclockwise   while   looking   in   the   viewfinder   to determine if the picture is in focus. Focus Two  methods  of  setting  the  focus  on  a  zoom  lens are  used.  One,  called  zoom  focus,  is  done  by  zooming all the way in and setting the focus, then zooming out to the desired focal length. Once this is done, everything in the  depth  of  field  will  remain  in  focus,  including  the object focused on, provided the distance between it and the camera does not change. Another focusing method is called rack focus. This is nothing more than your setting the focus on something in the field of view. When you do this, only that object and  other  objects  at  the  same  distance  will  remain  in focus  as  long  as  the  distance  between  them  and  the camera does not change. You  should  rack  focus  when  there  is  not  enough time to zoom focus. However, there are times when the effects  of  a  rack  focus  are  desirable,  such  as  when  the viewer’s  attention  is  directed  toward  something  in  the foreground and you want to lead him to another object. You can do this by changing the focus to bring the other object into sharp focus while the first object goes out of focus. f/Stop As   noted   earlier,   the   camera   pickup   tube   will operate  properly  only  within  a  certain  range  of  light intensity.  If  too  much  or  too  little  light  falls  on  the pickup tube, the picture quality will suffer. Since  you  will  use  the  camera  both  indoors  and outdoors, you must compensate for extreme differences in  light  levels.  The  lens  diaphragm,  or  iris,  is  used  to control the amount of light  that  enters  the  lens and the camera   by   enlarging   or   reducing   the   aperture.   The f/stops indicate the size of the lens (diaphragm) opening. 14-7







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