Exposure
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  • An exposure reading is taken by pointing the camera at the subject while looking through the viewfinder.
  • The build-in meter measures the light being reflected back from the subject to determine the correct exposure rehired.
  • Then set the aperture and shutter speed combinations accordingly.


There are 4 factors that need to be taken into account when determine the correct exposure for a picture
THE LIGHT LEVEL

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THE FILM SPEED

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THE APERTURE



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THE SHUTTER SPEED
A lot of light  ................................................................................................  brief exposure
Low light   .....................................................................................................  longer exposure
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Slow speed  .................................................................................................  long exposure
Fast speed  ..................................................................................................  short exposure
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CONTROLS THE AMOUNT OF LIGHT TO THE FILM
eg f/8  .......................................................................................  half as much light as f/5.6
                                                                                           twice as much as f/11
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CONTROLS THE LENGTH OF TIME THE LIGHT PASSES THROUGH THE LENS TO THE FILM
eg 1/60 sec  .............................................................................  half as much light as 1/30
                                                                                            twice as much as 1.125
  • Before taking a picture, measure the light levels - this may be done automatically.
  • The aperture and the shutter speed produce the exposure.  These can be used in various combinations to get exactly the same amount of light to the film.