Photo Tip #2 - Depth of Field and Placement of Focusing Point

In photography, there is this very important term called 'Depth of Field'. An object in sharp focus will have a degree of acceptable sharpness in front of it and behind it. That distance from the front up to the back of the object in focus having acceptable sharpness is the depth of field.

The depth of field will depend on three factors namely, lens focal length, aperture and distance to subject. To keep things simple, generally the wider the lens, the smaller the aperture (higher number F/ stop), and the farther away you are from the subject, the greater the depth of field.

In most consumer cameras today, there are different picture taking modes you can use just by turning the 'dial' to any of the ff.: Portrait, Landscape, Sports, among others. Portrait mode is when the camera sets the aperture to a bigger aperture (lower number F/ stop; i.e. F/2.8 or F/4) thus creating a more selective focusing technique where the depth of field is shallow. Landscape mode is completely the opposite, the camera sets the aperture to a smaller one (higher number F/ stop, i.e. F/11 or F/16) where the depth of field will be longer. All things being equal, the shutter speed will vary to accommodate the change in aperture.

Now when confronted with where to focus in a scene where you want your subjects (i.e. group of people) in focus from the subject closest to the camera to the subject farthest away from the camera, lock your focus (see photo tip # 1) slightly in front of the midway point of your subjects' positions. Why? Generally at any aperture, there is about twice the depth of field behind the point of focus as there is in front of it. You just have to meet the minimum aperture setting for the given situation.

In the old film days, those manual focus lenses have a 'depth of field scale' built in but they're not available now, not even with autofocus (AF) lenses. If your camera has a 'depth of field' preview button, use it. This is just harder to use in low light situations but if you understand the principles I've mentioned here, you can do without it. It's just more important to focus properly when you're nearer to your subject as depth of field is shallower.