A free resource from www.gcsephotography.co.uk

1. Introduction to Digital Photography
www.gcsephotography.co.uk
Each of the combinations of shutter speed and aperture below will give the
same exposure.
Choice of combination will depend on what you are trying to achieve in your
photograph!
As we move to the left, there is more chance of ‘camera shake’. Always try to use a shutter speed greater than the fo-
cal length of your lens if the camera is unsupported. (eg 60 for a 50mm lens.)
As we move to the right, there is less chance of ‘camera shake’. A higher shutter speed will freeze motion.
As we move to the right, each ‘stop’ lets in half the light. (Remember the number is a fraction of a second (eg 60
equals 1/60th of a second.
4 8 15 30 60 125 250 500 1000 2000
22 16 11 8 5.6 4 2.8 2 1.4 1
As we move to the left, each ‘stop’ lets in half the light. (Remember the number comes from multiplying by the square
As we move to the left, each ‘stop’ gives us more Depth of Field—an increase in the amount of the photo that appears
to be in focus.
As we move to the right, each ‘stop’ gives us less Depth of Field—a decrease in the amount of the photo that appears
to be in focus.
The ‘f stop’ of a lens is calculated as the focal length divided by the internal
diameter. (eg a 50mm lens with an internal diameter of 25mm will be f2.
Although it seems complicated at first, this means that the ‘f stop’ doesn’t change if you
changes lens’. (f8 is always f8—on every lens).
1