I recently attended a short college course where many of the people there had little photography experience whatsoever, it seemed one thing they had trouble fathoming was Aperture and after 15 weeks still didnt really understand it, so here goes my version.

Aperture is a hole through through which light travels the bigger the hole the more the light comes through the whole and vice versa.  Aperture is measured in F numbers or F stops and the Aperture opening is in your lens, if you look into the lens from the front you will see the opening, normal lenses usually go from about F22 to F4 but you can buy lenses which go down as far as F1.2.

Now, are you with me so far? everyone normally gets confused about now!  The Aperture not only controls the light coming into the camera but also the Depth of Field or DOF for short, this basically means how deep into your shot is in focus, the bigger the hole the less you have in focus, the smaller the hole the more you have in focus.  So here is a simple way to remember how the F numbers work:

F22 - Big Number - small hole - Lots in Focus, everything is sharp large DOF
F11 - middle number - medium size hole - some things are in focus but further into the background isnt
F4 - Small number - big hole - small area in focus very shallow DOF

               F4                            F8                           F22

    Very Shallow DOF    Medium DOF          Large DOF
     Not much Focus     More in Focus    Everything in Focus

So when you seen these lovely photo's of flowers where just the flower is in focus but the background is a blur the Aperture used was probably somewhere around F11 - F8 or maybe even lower F5.6 depending on the size of the subject.

This is particularly useful if you want your subject to stand out or you want to get rid of an unwanted background, however because the adjustments Aperture change the amount of light coming in through the lens then you might need to adjust the shutter speed or maybe even the ISO to compensate.  Try practising on the Aperture priority setting by changing the dial on top to either A or Av depending on your model of camera, then the camera will choose the shutter speed for you and you will only need to change the ISO, however do remember that the higher the Aperture (F22) then the Shutter will be open for longer and could result in camera shake so you may need a tripod to avoid camera shake.

Go from one end of the scale to another and practise each end to help you get used to the differences, oh and dont forget to have fun!


Aperture F5

Aperture F9

Aperture F14

Aperture F22

Aperture F29