When to use single shot AF

Known as One-Shot AF (Canon) and Single-servo AF (Nikon), use this when you’re shooting static subjects. It’s the default mode, as it won’t let you take a picture until the camera gets something in focus. Once it has, the camera locks this position for as long as you keep a light pressure on the shutter-release button.

Single shot AF is perfect for most shooting situations. The picture will be sharply focused, unless you move closer or further away from the subject after locking focus.

When to use continuous AF

AI Servo AF (Canon) and Continuous-servo AF (Nikon) adjusts the focus as long as you press the shutter release. It’s the best mode to use when shooting moving subjects. The focus position is never locked, and the camera will let you fully press the shutter to take a picture even if the subject isn’t in focus.

When to use auto select AF

AI Focus AF (Canon) and Auto Select AF (Nikon) are ‘intelligent’ modes that switch from single shot to continuous autofocus when the camera detects a moving subject, and vice versa. It’s a good choice when you’re photographing unpredictable subjects – if taking portraits of a bird that might take off, for example.

When to use manual focus

Manual focus (MF) requires you to manually focus the lens by twisting its focus ring. It’s useful in low light photography, when the camera’s autofocus system can struggle, or when subtle focus adjustments are required, such as in close-up and still life photography.

When to use Autofocus Lock

All digital cameras let you activate the autofocus system by lightly pressing the shutter-release button, but many also feature an AF button that does the same thing. You can usually customise the operation of both of these buttons, such as removing the autofocus from the shutter release altogether or enabling the rear AF button to stop autofocus instead.

But why would you want to stop autofocus? If you’re tracking a moving subject and for some reason it becomes obscured, you can temporarily switch off autofocus to prevent the lens from refocusing.

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Can you imagine tracking a fast-moving tennis pro without lightning-quick AF? Thankfully, today every camera, from the humble mobile phone to a consumer SLR, has a sophisticated and accurate AF system.

Image by David Clapp

Phase Detection vs Contrast Detection AF

Autofocus (AF) is split into two categories: Phase Detection and Contrast Detection.

The former is used in DSLRs: it takes some of the light hitting the mirror inside and redirects it onto a separate AF sensor. The sensor can calculate whether the subject is in focus very quickly, which makes it highly useful for tracking moving subjects.

Contrast Detection, found in point-and-shoot cameras, uses the actual imaging sensor to calculate focusing. It starts by focusing at infinity, checking the subject for contrast. If the subject is close, it appears very blurry and subsequently lacks contrast.

The camera moves the focusing and as it does so the image contrast increases. This is why point-and-shoot cameras operate far more slowly and often less intelligently than DSLRs.

What are camera focus points?

Inside a modern DSLR is an array of focusing points that can be seen through the viewfinder window. These points are sophisticated aids that allow the focal point of the image to be positioned by the photographer according to the subject.

A central focusing point is of little help to a portrait photographer, who relies on a left or right bias to position their subject’s face accordingly. When shooting moving kids in particular, in-camera technology is extremely helpful.

Once focus lock is attained using the centre spot, if the subject moves around the frame, the position is passed on to the other points.

Static and Continuous focus

Static or continuous AF modes give you a choice of subject-dependent tracking options. One-shot modes, for example, are great for static subjects like portraits, while Servo focusing focuses continuously with the shutter half depressed.

The AI Focus mode offers the best of both worlds, switching between the two modes automatically, initially static but then tracked if the subject moves.

Focus your camera with Live View

Focusing isn’t always about in-camera calculations. The Live View revolution enables you to gain pinpoint accuracy by using a magnified view of the subject.

In low-contrast situations – when shooting into the sun, for example – AF can be inaccurate.

Live View can minimise inconsistencies or the irritation of ‘hunting’, where the camera searches the focal range while attempting focus lock.

PAGE 1: Ways to focus your camera
PAGE 2: Set up for spot-on focus
PAGE 3: Get the eyes sharp
PAGE 4: Focus on off-centre subjects
PAGE 5: Tips for controlling focus

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OK, so remind me, which focus mode should I use for moving subjects?

Your DSLR features two basic autofocus modes: one for shooting stationary subjects and one for moving subjects.

Single-shot autofocus mode, aka One-Shot AF (Canon DSLRs) and Single-servo AF (Nikon DSLRs), is the best mode for subjects that aren’t moving – and in this mode the camera won’t be able to take a picture until the image is in focus. It’s well suited to a wide range of subjects, from portraits to close-ups to landscapes.

The downside is that once the focus is locked at a certain distance, it stays locked there for as long as you keep the shutter release half-pressed. If the subject you’re photographing suddenly moves closer to the camera or further away from it, then they’ll drop out of focus and appear blurred.

The only way around this is to take your finger off the shutter release and half press it again to trigger the autofocus system. As you can imagine, repeatedly doing this to 
keep track of a rapidly moving subject soon becomes tedious.

Choose the continuous autofocus setting on your camera, also known as AI Servo AF (Canon) or Continuous-servo AF (Nikon), and the camera will continuously adjust the focus of the lens while light pressure is maintained on the shutter release.

If the subject moves before you take the shot, no problem – the focus system will continue to track it right up until the moment you release the shutter.

Will my camera switch between these two autofocus modes?

No. You’ll have to do it yourself. Many cameras feature a button marked ‘AF’; by pressing this and then rotating the camera’s main dial, you can switch between these autofocus modes.

More advanced cameras, such as the Nikon D300s, feature a dedicated focus mode switch you can use to set the focus mode directly: Continuous (C), Single (S) or Manual (M).

That said, camera manufacturers appreciate that newcomers to photography might not be able to predict when they need to change the autofocus mode, so many models feature a mode that automatically switches between the two.

Set your camera to AI Focus AF (Canon) or Auto Select AF (Nikon) and it will automatically shift from single focus to continuous focus when it senses a moving object.

So, if I spot a moving target and select the continuous focus mode, the camera will automatically focus on it?

It will, as long as the moving target is covered by an active focus point. Cameras have multiple focus points arranged around the centre of the frame, and you can select just one or a small number, or activate them all.

The greater the number of focus points and the more densely packed they are, the more chance there is of the focus system tracking a subject accurately as it moves around.

But there are advantages to manually selecting an individual focus point instead. If all the focus points are active and you’re taking pictures of a subject that isn’t very big within the viewfinder, or the scene has lots of confusing detail in the background or foreground, then the focus system may have trouble locking onto and tracking the subject.

Manually selecting a single focus point means the camera will only focus on the area you choose. This means you have to move the camera in order to keep the focus point locked onto the subject.

Isn’t it hard to keep a moving subject in focus using a single, small AF point?

Yes, it can be tricky if it’s moving fast
– or erratically! This is why cameras come loaded with advanced AF point selection options.

Take the Nikon D5100, for example. It features four AF-area modes: Single Point, Dynamic Area, Auto Area and 3D Tracking.

In Single Point, simply choose the AF point from all of the available ones. Dynamic Area gives you more flexibility. 3D Tracking mode lets you highlight the subject using one AF point, with the camera automatically switching to a different AF point to keep them in focus. 
Auto Area makes all autofocus points active and automatically selects what will be in focus.

Should I use continuous drive mode when I use continuous autofocus?

Yes, using your camera’s continuous drive mode enables you to capture a sequence of shots when the shutter release is pressed. The speed at which the camera can initially focus on a moving subject is also key.

The camera starts taking pictures when you fully press the shutter release in continuous focus mode, regardless of whether anything is in focus or not. With a fast-moving subject, there can be a delay as the autofocus tries to lock onto the subject and begin tracking its movement.

There are ways to improve this. Using a lens with a maximum aperture of f/2.8 can make use of a camera’s more sensitive ‘cross-type’ autofocus sensors for improved accuracy.

Pre-focusing the lens at a distance at which you expect the subject to pass also reduces the amount of work the AF system has to do. Some lenses even have a focus limiter switch, which allows you to restrict the distance over which the lens will focus.

But there will still be some instances where it pays to use manual focus.

Switch to manual focus for action photography? Really?

Even ultra-slick focus systems can struggle to keep every frame in focus. In motorsports, for example, cars can hurtle towards the camera at a higher speed than the autofocus can keep up with.

With predictable action like this, it often pays to pre-focus on a spot using single-shot focus, then switch to manual focus to lock the focus distance in.

With the fastest drive mode selected, fire a burst of shots at the optimum moment when the car arrives at the focus distance, maximising your chances of at least one frame being sharp.

PAGE 1: Common questions about using autofocus with moving subjects
PAGE 2: Focus modes explained
PAGE 3: How to set up your camera for action photography

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This guide is written for anyone who wants to get more from their camera, be it an SLR, compact system camera or bridge camera. It works as a complete beginners’ guide, but is also a handy refresher course for people who’ve had their camera for a while.

I remember how intimidated I was by my first ‘proper’ camera, and how much I could have benefitted from a jargon-free guide like this. In the articles below, you’ll learn all about your key camera controls – what they are, and more importantly, how to use them to get great shots. Read on to discover how to control exposure for perfectly balanced shots, adjust aperture and shutter speed, use flash, and much more. We also explain how to choose and use a lens, and how to get more from your photo-editing software and printer. Enjoy this unique beginners’ guide, and please do share any shots it’s inspired you to take!

Part 1: Set up your camera

Part 2: Explore your SLR

Part 3: Get better exposures

Part 4: Understanding aperture

Part 5: Shutter speed explained

Part 6: Perfect your exposures

Part 7: Focus modes explained

Part 8: Choosing a lens

Part 9: Flash modes explained

Part 10: Image editing, printing & storing

Part 11: Essential accessories

Part 12: Looking after cameras

Congratulations on getting a new camera! It’s only natural that you can’t wait to start using it, but it’s worth spending a few minutes configuring it correctly first. Not only will this save you time and effort in the long run, but it’s a good way of familiarising yourself with your camera’s layout, features and functions. With the help of our quick-start camera set-up guide, it will only take a few minutes…

Select high-quality pictures

When it comes to file format, shoot in raw rather than JPEG. The extra data that’s captured in the uncompressed raw format gives you more flexibility to adjust your shots post-shoot if necessary (see page 7 for more on the raw file format). Try to keep the ISO as low as possible, ideally between ISO100 and 400, because digital ‘noise’ can be a problem at high ISO settings. As for white balance, set it to auto for now – as you progress you’ll become more confident at knowing when to switch to a specific setting, such as Cloudy.

Choose the right exposure mode

SLRs offer a range of exposure modes, from fully automatic – like a point-and-shoot camera – to fully manual. In between these two extremes are the two popular ‘semi auto’ modes – aperture priority and shutter priority – which provide lots of creative control. In aperture priority mode, you set an aperture and the camera automatically works out what shutter speed you need for a correct exposure, while in shutter priority mode, you set the shutter speed and the camera works out the correct aperture. Simple!

Choose the right metering mode

Metering options depend on the camera, but the three most common are multi-zone (also known as evaluative or matrix), centre-weighted, and spot. Multi-zone mode takes a reading from the entire scene and then sets the exposure accordingly. It’s pretty accurate, and is suitable for most conditions. Centre-weighted mode takes a reading that concentrates on the central 60% of the frame, making it ideal for portraits, and spot mode takes a reading from a tiny area and is therefore potentially the most accurate.

Set the aperture and shutter speed

Aperture and shutter speed affect not just the amount of light you let into the lens, but also the way images look. The aperture is used to determine the depth of field, which is the amount of the scene that’s in focus. If you want a blurred background, you need a wide aperture, such as f/2.8; and if you want everything in focus from front to back, you need a narrow aperture, such as f/22. The shutter speed controls whether a moving subject is frozen or blurred; the slower the shutter speed, the more motion blur there will be.

Set the focus and drive modes

To ensure your shots are razor-sharp, SLRs offer a number of focus modes. The two main settings are single-shot, mainly for stationary subjects, and continuous or servo, for moving subjects. Most SLRs feature multiple focus points that can be selected manually. The drive modes enable you to select whether a single shot is captured each time you press the shutter release, whether a sequence of shots are taken in rapid succession, or whether the shutter is fired after a delay of two or ten seconds.

Take a test shot

Now you’ve set up your SLR, it’s time to ensure you’re using its LCD properly. By this we mean using the zoom buttons to zoom in on parts of the image on the rear screen, so you can check for sharpness or excessive noise. And you should also try to get into the habit of checking your image’s exposure by calling up the histogram, or tone chart. A histogram bunched up at the left can indicate under-exposure; a histogram at the right suggests over-exposure. If you’re unsure, adjust your settings and try taking another test shot.

Back to: Get to know your camera – introduction

Forward to: Explore your SLR