Recently, I posted that my biggest frustration is improper focus.

If you use a point-and-shoot, the solution it pretty simple. You hold down the shutter button halfway until focus is achieved and then push it the rest of the way down. The only reason you’d be likely to end up with poor focus is, as I said before, you’re shooting in an improper mode. For example, you’re shooting a landscape in macro mode.

For us DSLR users, focus becomes another monster all together.

{Factor 1 – Selecting Focus Mode}

The first thing to consider is the mode you’ve set for your camera. In the menu, there will be an area for ‘AF Modes’. The three you may see are:

1.} One-Shot – Suitable for still subjects. Press the shutter halfway and the camera will focus only once. If the subject moves or you want to recompose the shot, you must release the shutter and press it halfway again to refocus.

2.} AI Servo – Also known as ‘continuous focus’ on a Nikon, AI Servo is used to keep a continuous focus on moving subjects until the shutter is pressed all the way. The ‘AI’ stands for ‘artificial intelligence’ and the camera uses these algorithms to predict where a subject is about to be. This is the setting to be used in sports photography and I use it with children on the go. Wikipedia’s entry on AI Servo says it so well: “Before servo focus the photographer would generally pre-focus on an area where he/she thought the best action would take place; today he/she can follow the entire sequence of events, and select the best later.” In AI Servo mode, the camera won’t beep once focus is achieved. It just keeps focusing until you decide to take the picture.

3.} Al Focus – AI Focus mode starts with normal one-shot focussing (hold the shutter down half way and it will beep when focused) but if the subject starts moving, it will switch to AI Servo mode. Certainly, this is clever of the camera, but Nikon doesn’t even have this option. Why? Your subject is either a living, breathing, moving being or it isn’t. I’m either in One-Shot or AI Servo. AI Focus just seems kind of dumb to this Canon user

{Factor 2 – Selecting the AF Area}

In my camera (A Canon 7D) there are three AF Areas and it should be pretty much the same in most cameras.

1.} Single Point AF – this selects one spot to be used for focus. In the viewfinder, you’ll see the little square and you press the shutter halfway and the camera will beep to let you know that focus has been achieved. This mode is useful if you often follow the rule of thirds because you can focus on your subject, slowly re-compose the shot and take the photo. Your subject will be in focus.

2.} Zone AF – Focus points are organized into five different groupings, and the camera uses one of the points in the group to autofocus. Can be used in the thirds composition as above but offers a bigger area for focus, useful for tighter shots and portraits.

3.} Auto Select 19-point AF – All 19 available autofocus points are used. If multiple areas are in focus, all of these points will light up in the viewfinder. This is the mode used in full auto and creative auto modes. Pressing the shutter halfway will display the AF point(s) which have achieved focus. If multiple points are displayed, it means they all have achieved focus. This mode tends to focus the nearest subject. Great for moving subjects.

In this post, Steve Berardi from PhotoNaturalist talks about three ways to get better control of autofocus.

Sometimes autofocus can be really annoying. For some shots it’ll focus on the right part of your subject, but then the very next shot it may choose to focus on something far and away into the background.

Sure, you could avoid this problem by always using manual focus, but autofocus is great when you need to focus quickly or when you’re photographing a landscape and you need to focus on a certain spot in the scene.

Well, autofocus doesn’t have to be annoying anymore, because here are three ways to get better control of it:

#1 – Press your shutter button half-way to activate autofocus and then recompose

Set your autofocus point to the center spot, then point this spot where you want to focus and press your shutter button half-way (don’t press it completely yet) to initiate autofocus. Then, while still holding down the button half-way, recompose your shot and press the button completely down to snap the photo.

#2 – Switch to manual focus after autofocusing

Use autofocus as you normally do, but once it focuses on the right spot, just switch off autofocus on your lens to manual focus. Your lens will keep the current focus when you do this. This method works well when your camera is on a tripod and you’re taking multiple exposures from the same spot, like when photographing a landscape.

#3 – Use back-button autofocusing

Normally, your camera will autofocus when you press the shutter button, but with back-button autofocusing, you have to press a button on the back of the camera instead, giving you complete control of when autofocus is initiated.

With back-button autofocusing, you can just set the autofocus point to the center spot, then point that where you want to focus, and finally press the back button to automatically focus on that point. Now for all the shots you take from that position, that focus will be maintained (the camera won’t randomly focus into the background anymore).

You can do the same thing without this back-button autofocusing by switching to manual focus after the camera focuses properly, but using the back button saves time and this way you don’t have to constantly switch back and forth between manual and autofocus (which can inadvertently move the camera sometimes).

Back-button focusing is especially helpful for photographing moving subjects, like birds in flight or other wildlife: just switch on the continuous focusing mode, set the autofocus point to the center spot, and hold down that back button. Now you don’t have to worry about accidentally hitting the shutter button while you’re tracking the subject in your viewfinder.