• APERTURE: an opening in the lens that changes in size to control the AMOUNT of light passing through the lens of the camera.
  
  
• APERTURE PRIORITY MODE: an automatic camera mode where you set the camera's aperture and the meter will set the shutter speed for correct exposure.
  
  
• DEPTH OF FIELD: the distance between the nearest and farthest objects in a scene that appear acceptably sharp in an image.
  
  
• STOP: A stop is a doubling or halving of the amount of light let in when taking a photo
  
  
• F-STOP: A fraction that measures of the size of the aperture opening on a camera.
  
  
• IRIS: The part of a lens mechanism that can expand and contract to control the amount of light passing through a lens.
  
  
• ISO: A system used to measure and adjust how sensitive a digital camera is to light.
  
  
• RECIPROCITY: when you ADD a "stop" of light entering the camera with one of the camera exposure controls (i.e. shutter), then BALANCE it by taking AWAY a "stop" of light with the other (i.e. aperture)
  
  
• SHUTTER: The device on a camera that opens and allows light to pass to the sensor or film for a set period of time in order make an exposure.
  
  
• SHUTTER SPEED: the length of time a shutter remains open as measured in seconds or fractions of a second.
  
  
• SHUTTER PRIORITY MODE: A camera shooting mode that lets the photographer define the camera's shutter speed and the camera will then set the aperture for a correct exposure based on its light metering.
  
  
• NOISE: (Digital Noise) Visual distortion consisting of tiny grainy colored pixels or specks in photographs taken in low light situations with high ISO.

• MANUAL MODE: A mode where the photographer can control all camera settings (Shutter Speed, Aperture, ISO, WB, Flash, etc.)

• METERING: It is the process of measuring light with a light meter to determine the correct exposure. Cameras meter at 18% gray.

• EXPOSURE COMPENSATION: A camera feature to allow the user to adjust the automatically calculated exposure. 

UNIT RESOURCES: