Ever seen a portrait photograph where the person seems to pop out from the scene? Or a landscape which looks almost 3D, with everything from the nearest rock to the furthest mountain in focus?
This is due to depth of field (DOF) and understanding how it works will radically change your photographs. Here is my sixty-second tip on how to control it and how it will affect your images for the better.
What is depth of field?
It is the distance between the nearest and furthest objects that are in acceptable focus. A shallow DOF might be just an inch whereas a large DOF can be hundreds of meters.
How do you change it?
Primarily by controlling the aperture – and this is where things get counter-intuitive. A large aperture (e.g. f/1.8) creates less DOF; a small aperture (e.g. f/16) creates greater DOF.
Aperture-priority – as advocated in my previous tip – is an extremely useful mode for getting your head around the relationship between aperture and DOF.
Any other factors?
Other variables that will influence your DOF include your focal length (longer focal lengths create less DOF), the distance between you and your subject, and the sensor size of your camera. More on this another time though.
Why change it?
Because it allows you to determine exactly what you want to draw attention to. With a portrait that is almost certainly the subject, in which case you won’t want to have a distracting background which is why shallow DOF is preferable. It will leave your subject in sharp focus but blurring out everything else.
With a landscape you are likely going to want more DOF to enable as much of the scene to be in focus as possible, which in turn gives a greater sense of (you guessed it) depth – creating a more immersive feel.