Exposure

1
Exposure

• Controlled by Aperture Shutter
• Shutter is diaphragm inside back of camera that
  opens and closes to allow light to reach film
• Shutter speeds are marked in seconds
• Slower speed more exposure faster speed
  less exposure
• B setting on shutter stays open as long as
  shutter release button is held down. Longer time
  than on scale above.

2
Exposure

• Each shutter is half the preceding one. It
  changes by a factor of 2 each time we move the
  shutter speed dial. Ex. 1/125 is half the
  exposure of 1/60
• Aperture iris type diaphragm with variable
  openings.
• F stops settings along the control ring.
  Mechanism which controls the aperture size.
• Scale
• More exposure opening up Less exposure
  closing down

3
Exposure

• Changing one step on scale changes film exposure
  by a factor of 2. Ex. F 5.6 gives twice the
  exposure as f 8.
• When aperture is moved one step and exposure is
  changed (by a factor of 2) it is called one stop
  in exposure
• Opening up one stop Doubling exposure
• Closing down one stop Halving the exposure
• Settings on aperture ring are designated as f
  -stops.

4
Exposure

• Exposure can be doubled in 2 ways
• 1. Move f-stop to next smaller f-stop . Ex. f
  5.6 to f 4)
• 2. Move shutter speed to next smaller (next
  slower speed). Ex. 1/250 to 1/125
• Exposure Increments
• One stop 2 times the exposure
• Two stops 4 times the exposure
• Three stops 8 times the exposure

5
Exposure

• Equivalent Exposure Settings a set of pairs of
  shutter speed f-stop settings which produce the
  same exposure.
• Ex. F 8 / 1/60 f5.6 / 1/125
• This is because f5.6 is twice the exposure of f8
  but 1/125 is half the exposure of 1/60, so
  therefore they are equal exposure.
• It is important to understand equivalent
  exposures when you are considering depth of field
  and film speeds.
• Reciprocity The equivalent film exposure pairs
  also produce equivalent density on film. Follows
  same conditions as above in the equivalent
  example..HOWEVER! It fails to produce
  equivalent density with long or very short
  exposure times. Gives less density. Can be
  corrected by changing exposure time or aperture.