Aperture, Light and Stops
// February 28th, 2010 // Photography
This is a diagram I drew to understand aperture numbers (the f numbers on a lens) and the concept of stops. In the graph, the gap between each bar is a stop (click to enlarge):
The most confusing thing was always the non-linear nature of stops – an increase of one stop of light means that the amount of light has doubled, a reduction by a stop means a halving of the light.
You can see the diaphragm of a lens here (the white circle in the centre, ie. the hole that lets the light through):