Simplifying your focus options

When you first picked up your big camera and took a photo on auto-everything, it probably came out OK and your shot was in focus. Auto-everything is fine for focussing on generic views, groups of people and holiday snaps.

Image Patrick Selin, with permission

Image Patrick Selin, with permission

But if your subject is anything slightly different, you might find your camera won’t focus in the right place. For example:

  • you want to focus on something that is quite close to you, but the camera will only focus on the background or it won’t take the photo at all

  • you want to pick out a particular tree in a group, but the camera picks the wrong one

  • you are photographing something small like a bird or a butterfly, but the camera will only focus on the flower behind it

  • the subject is moving quickly, and the camera focusses on the wrong part of the image

  • the shot is very low contrast or you are shooting at night, and the camera can’t find anything to fix its focus on

As soon as you start having problems with focus, you need to take a bit of control away from the camera. Your options are set out below.

You will need either your camera manual or a screen open with YouTube ready to go so you can search for how to do a particular thing on your make and model of camera.

If you want help moving off other auto modes (auto exposure, auto white balance), sign up for my complete beginner’s workshop at the end of this post. The email version is completely free.

Autofocus (“AF”)

Your camera probably has three AF options – check your manual to see what they are called for your camera and how to change which one you are using (eg. Canon calls Continuous AF “AI Servo”; Nikon calls it “Continous-Servo”). When you are using auto focus (as opposed to manual focus) your camera will use whichever of these three options you have selected.

  1. Single shot AF: use to lock on to a stationary subject (usually the default option)

  2. Continuous AF: use with a subject moving across the frame (the camera tracks the subject and changes the focus point as it moves – it also uses a lot of battery power)

  3. Automatic AF: the camera chooses which of the previous two AF options to use based on its algorithm

Use continuous focus AF to track moving subjects.  Image Jeff Griffith, with permission

Use continuous focus AF to track moving subjects. Image Jeff Griffith, with permission

AF points

You will need to know about your “auto focus points”. When you look through your viewfinder, these are the small rectangles overlaid on the image. The default option is that the camera uses all of them, but you can also opt for a single AF point – and you can choose which one. With the default option the camera prioritises whatever is in the centre of the shot, but this is not always what you want. By choosing an AF point that aligns with your off-centre butterfly or tree, you can force the camera to ignore everything else.

The downside is that it takes a little while to set up for each shot and your butterfly may have moved on. If this happens, you might try the continuous focus AF option. Or, if your camera has the option, use the touch-screen to move the focus point.

If your camera has a live-view option on the LCD, you may not see the AF points overlaid. What usually happens is that the single AF point or group of AF points that the camera has chosen to lock focus on will light up when you press the shutter.

Manual focus (“MF”)

The camera focusses by finding edges – areas of high contrast. If your camera can’t find enough edges or areas of high contrast to achieve focus (eg. you are trying the first lesson in A Year With My Camera and taking a photo of a blank piece of paper, or you are shooting the night sky) it may refuse to take a photo.

The easiest option is simply to move your camera from AF to MF. Don’t forget to put it back again afterwards. For most cameras the AF-MF switch is actually on your lens. But for a few bridge cameras you might need to delve into a menu to bring up the AF/MF options.

Manual focus is also useful if you are working with a very shallow depth of field – with macro work for example. It’s always useful to know how to switch to MF just in case none of the AF modes work for you in a particular situation.

If you ever need to pre-focus your camera, manual focus is by far the best way to do this. For example, if you are waiting for a racing car to come past so you can try a panned shot, or you are set up in a bird hide waiting for a kingfisher to alight on a branch).

Half-press shutter method

To gain fine control over where the camera chooses to focus (using AF) without having to scroll through your AF points each time you reframe a shot, you can use the half-press shutter method. (This only works if you don’t have back button focus (“BBF”) enabled – see below.)

Without BBF enabled, the shutter button has 2 functions:

  1. to fire up the AF and tell the camera to choose a focus point (at which point the camera also, incidentally, chooses the exposure based on the AF points), and

  2. to fire the shutter and take the photo.

You can pause the process between points 1 and 2. This means you can achieve focus, then move the camera and reframe your shot without losing the original focus.

This is a very useful technique to master if you want to avoid having your subject in the middle of every photo, but also want to use the camera’s AF. If you were taking a photo of this butterfly but didn’t want it to be framed centrally, you would half-press the shutter with the butterfly in the middle of the shot until you hear the “beep” to indicate you have focus (or the AF points in the centre flash up green, depending on how you have your camera set up):

Image Boris Smokrovic, with permission

Image Boris Smokrovic, with permission

And then – critically – keep the shutter button half-pressed while you reframe your shot. If you let go of the shutter button you will lose your focus. Once reframed, press the shutter button all the way to take the shot.

how to focus on a butterfly 2.jpg

You can combine the half-press shutter method with using a single AF point. If you know you always prefer your subject to be off-centre to the left or right, you can select a single AF point in approximately the correct place to avoid you having to make large reframing corrections.

Back-button focus (“BBF”)

On most cameras you can split the 2 functions of the shutter button. You can leave the shutter button simply to fire the shutter and take the photo. And you can assign another button to manage the focussing process. This other button is usually under your thumb on the back of the camera, hence “back-button” focus.

If you have been shooting for a while, using BBF can take a while to get used to. It can be complicated to set up, and you need to commit to using BBF exclusively for a week so you get rid of your half-press shutter habit. I have recently made the switch and yes it was worth it. It’s quicker and more accurate, and you don’t have to hold the BBF button down whilst you reframe.

For my Canon 5D I had to first uncouple the shutter button focus + fire function, and then assign a button for the BBF. The first step was buried in a custom function menu, and I strongly recommend browsing YouTube to find a video of someone walking you through each step.

Touch screen

Newer cameras make the whole focussing process very easy. If you have a touch-sensitive LCD you can probably simply touch the live-view image to both focus and take the shot. This is a great option for subjects that are finger-sized on the LCD (eg. people’s heads) but it is a bit heavy-handed if you need finer control (eg. macro). You can probably split the focus/fire options like you can with BBF: it’s usually possible to set the camera up so you touch the screen to focus, and then use the shutter to fire. (This gives you time to check you have the focus right.)


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