Table of ContentsPage 1: Depth of Field - the science bit. Page 2: Depth of Field - Close-ups & Bokeh.
Sometimes, as in the photo on the right of the coffee cup, you want as much of the scene in focus as possible. So it is necessary to set the smallest aperture (biggest f-number) that the lens allows. This is especially important when shooting small objects in close-up as the depth of field gets thinner as your picture area gets smaller. When shooting macro 1:1 the DOF can be only a few millimetres thick, and getting everything in focus can be a very demanding task. For more on macro photography see close-ups and macro 1:1.
Of course it's up to you how much of the scene you want in focus. Sometimes it can help to force the viewer's eye to the part of the picture you really want them to look at. I would say, as a matter of taste though, that, with a few notable exceptions, I like to see the foreground of a picture in sharp focus. If you break this rule, you need to do so knowingly and with good reason. Nothing shows up a beginner's attempt at close-ups more quickly than an out of focus foreground.
If the scene you are trying to photograph has a busy background, a really nice treatment is to use as wide an aperture as you can to minimise the DOF and throw the background out of focus. The resulting out of focus part of the picture has become known in recent years as the bokeh. This effect works better on close-up telephoto shots than wider angle stuff. It also helps to have a lens with a really wide aperture. The more expensive lenses tend to have wider maximum apertures, that's what you're paying for, all that precision ground glass.
Of course you need to be extra careful with the focusing when you do this, make sure the important parts of the picture are properly in focus, and there is enough depth of field to cover all the areas that you want to be sharp. The best way to ensure this is to take a few shots at different apertures.
Out of Focus Foreground
As I said earlier, most of the time it is better to have the nearest objects in the scene in sharp focus but here's an exception. On the right you can see a photo of wolves kept safely behind a fence, for which I am grateful, wolves in the wild are great but not when I am this close. However it makes it very difficult to get a decent picture of them. In the second picture, the fence is still between us, I have not been so foolhardy as to climb in with them, but I have made it 'disappear'. This is simply as a result of using a wide enough aperture to blur the fence to such an extent that you can't see it. Of course I had to put the camera on manual focus, the auto focus would have just picked out the fence as the nearest object. I then moved as close to the fence as possible, actually I couldn't get that close as there were two fences, but managed to get close enough, and focussed manually on the wolf's face.
Okay yeah, he is actually yawning rather than growling, but I wasn't going to provoke him too much. The important thing though, is to set your camera to Av or aperture priority, and get experimenting.
An introduction to composition, explaining the 'rule of thirds' and the use of diagonals.
Watch out for those ugly dustbins!
The most important rule of composition.
How to fill your frame with your subject.
Another important aspect of composition.
What it is and how to use it creatively.
How to use Motion Blur, and a discussion on when it's appropriate.
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