A short guide to these three concepts in photography .. Please comment if I have gotten my facts wrong =P .
Defined as the mechanism which determines the amount of light entering the lens which subsequently fall onto the image sensor.
Measured in f-stops. Eg: f/2.8 , f/4 etc. Smaller numbers represent a larger opening = more light received by camera.
Each change in f-stops either decreases/increases the amount of light entering by half. Eg : f/4 to f/5.6 –> decreasing light entering the lens by half.
Smaller aperture ( aka large f-stops )= larger Depth Of Field ( DOF ) . Since smaller aperture greatly reduces the amount of light entering the camera, we can compensate by having a longer shutter speed.
Larger DOF = almost everything in the image will be focused.
Smaller DOF = Only a small part of the image is being focused, rest being blurred.
Defined as the mechanism which determines how long light will hit the image sensor.
Measure in seconds.
Fast shutter speed = freeze motion, good for moving objects.
Slow shutter speed = blur effect, good for conveying a sense of movement.
Defined as the sensitivity of the image sensor to light.
Higher numbers = more sensitivity to light but more noise. ( Noise refers to the “rice grains effect” seen in some images )
Increasing ISO = faster shutter speed / smaller aperture. Can extend DOF to a certain extent.