Exposure Triangle - Aperture

 

It is a year since I gave a presentation on the Exposure Triangle so there was a request at our meeting last week to go over it again.  I remembered having seen a "cheat sheet" from Digital Camera World and suggested it might be a good idea to print it off to keep in your camera bag (or save it on a mobile device).

The diagram, above, shows:

• aperture (the size of the opening) DECREASING from top to bottom
• The amount of light entering the camera DECREASING from top to bottom
• the f Number (a measurement of the size of the aperture) INCREASING from top to bottom
• Depth of field INCREASING from top to bottom

So the thing to remember is:

if you want SMALL depth of field you need to select LARGE aperture/SMALL F number

if you want LARGE depth of field you need to select a SMALL aperture/LARGE f number

But remember, there has to be tradeoffs in the time your aperture is open, the sensitivity (ISO) of your sensor, and the optical performance of your lens.

There are also other factors that impact on depth of field, the focal length of your lens and the camera to subject distance.

We will discuss this all at our next meeting.