There are three parts of Exposure:
Aperture: The Lens Opening; AKA The F-stop (Inside the Lens)
Shutter Speed: How fast the shutter opens and closes (inside the camera body)
ISO: The numerical exposure index of a photographic film under the system adopted by the International Standardization Organization (ISO), used to indicate the light sensitivity of the film’s emulsion; AKA Film Speed (Relates to the Film and is set inside the Camera menu)
A Breakdown of each part of Exposure:
APERTURE:
Aperture works like the pupil of your eye–It gets wider in the dark and smaller in bright light.
Wide Apertures are used during low lighting situations to let in a lot of light. Examples of wide apertures: F/1, F/2, F3.5, F/4. Wide Apertures usually result in narrowing your depth of field.
Medium Wide Aperture is standard on all lenses: F/5.6
Small Apertures are used for very bright lighting situations to let in a small amount of light. Examples: F/22. F/24, F/30, F/32, F/36
SHUTTER SPEED:
How fast the shutter opens and closes can also control how much light enters a camera. A slower shutter speed lets in more light than a faster shutter speed. Shutter Speed is a fraction of a second.
BULB is a feature used to control how long the shutter stays open. With BULB, the shutter will stay open as long as you hold down the shutter release button.
Slow shutter speeds are used for low lighting situations and often require the use of a Tripod. Examples: 30” (“ stands for seconds), 25”, 15”, 1”, 1/10, 1/25, 1/30
Medium fast shutter speed is used for low action shooting situations and is standard on all cameras: 1/60
1/125 is the slowest shutter speed you can use to stop action. If you use a slower shutter speed, the action will blur.
Fast Shutter Speeds are used to stop action or can be used during extremely bright lighting situations. Examples: 1/500, 1/800, 1/1000, 1/4000, 1/8000
ISO:
The Film or sensor’s sensitivity to light, also known as Film Speed.
100 to 200: Used for Daylight
400: All purpose, indoors and outdoors
800 or higher: Low lighting
ISOs greater than 1600 will produce visual noise (grainy with film) in a picture. Visual noise appears as red, green and blue specks in the image.




