An easy way to bring a subject into focus is to use the auto-focusing mode on your camera. All you need to do is flick the focus mode switch to AF and press the shutter release button half-way down. Pressing the shutter this way allow the camera’s auto-focusing system to lock focus. But where does it lock focus? Now that’s a bit of a story.
Camera systems are designed in a way so that they look for contrast in the image. Contrast is where the bright bits of the image come side by side to the dark bits. An average camera will lock focus on this merging point. There is no telling where the camera will find the best contrast and thereby lock focus on. This is all fine when you are shooting landscape images, you don’t mind any specific area to be in focus because you are shooting with a larger f-number and everything by default is likely to be in focus.
But, when you are shooting something like portraits you simply cannot rely on the camera to pick the point of focus for you. You need to be able to decide yourself where you want to focus on.
Focus and recompose technique
The focus and recompose technique is the most widely used one for composing in photography. It is unfortunately a less accurate method and one that you should try to use as less as possible, especially when shooting still life. In this technique all you have to do is half-depress the shutter button, allow the camera to acquire focus and then recompose by moving the camera physically.
The reason that this method is very popular is because the center area of the frame is used in most cheap Point & Shoot cameras to lock focus on. Some entry level DSLR cameras with a single center cross-type AF point is also likely to be used this way, as the cross type AF point is more susceptible to detecting contrast both horizontally and vertically than the other AF points in the camera which can detect contrast in one direction only.
The problem with this method is that when you focus and recompose you are evidently moving the camera physically and there is a good deal of possibility that the plane of focus can change as a result. If the plane of focus changes, the point which you want to keep in focus may no longer stay on the plane of focus any more. The problem is accentuated when the depth of field is narrow, i.e., you are using lenses with a very wide aperture such as f/1.8 or wider wide open. A better method is to manually select the focus point, which of course is possible with DSLR lenses.
Manually selecting the focus point
Welcome to manual focus point selection. Here you are going to learn how to select a specific focus point you want to use for your images. When your camera is set to auto mode you may have noticed, half-depressing the shutter release button lights up several of the focus points instantaneously. Then only a single point remains activated. Depending on the camera make and model you may have 9, 11, 39, 51 or even more focusing points. So, ideally, if you could select just one of them, the one you want, you could have a better control over the image. The process on your camera is likely to be different than what I am going to state here. So, please check the manual that accompanied your camera.
Get out of the auto mode and select one of the creative modes, programmed auto, aperture priority, shutter priority or even full manual mode. In some cameras you will need to get out of Auto Focus point selection. If the LCD says something like ‘Auto’ against a matrix of focus points, you will not be able to select a single AF point. Half press the shutter button to activate the AF points. Now turn the main command dial to select the AF point that you need. Take the picture.
Being able to select the AF point manually allows you to create off center compositions more easily. All you have to do is compose, select the AF point that you wish to use and shoot. This method is more accurate than the focus and recompose technique that we discussed above and you don’t have to worry about putting the subject off focus.
Working with manual focusing
Manual focusing is the old fashioned way of focusing. Auto-focusing wasn’t always around and those who started photography around two or three decades back used only manual focusing. Some photographers still prefer the old fashioned way as it gives them a greater degree of control. With manual focusing you don’t need to do focus and recompose and you don’t need to bother about focus points and the technical mumbo jumbo.
At times however, the only method to reasonably do any kind of focusing is manual focusing. Let’s say you are shooting in pitch black conditions (star trails / fireworks / Milky Way photography). There is no way to use manual focusing in these conditions. Additionally, if you are doing video shooting, manual focusing allows you a better degree of control than auto-focusing.