Ensure your shots are always sharp with these tips, tricks and techniques for focusing
There’s no remedy for an out-of-focus photo, and many of us have felt the pain when a shot we thought would be a stunner turns out to be slightly soft. As such, focusing is one of the most crucial skills a photographer can learn. Thankfully, advances in cameras and lenses mean that it’s easier than ever to get perfectly sharp shots. But it still helps to know a few tips and tricks…
1 How should you focus?
There’s no right or wrong here, we all have our preferred methods. Some like to half-press the shutter button to focus, others swear by back-button focusing (this is where the default shutter half-press is disabled and a button near the thumb engages it instead). Live View focusing can be handy too, especially for tripod-mounted shots, as all you have to do is touch the screen to lock on to an area. Then there are intelligent autofocus modes in the newest mirrorless bodies, like face detection, eye detection and eye control AF, which cleverly detects the point in the frame you’re looking at.
2 Fine-tune your focus
Most cameras offer several ways to adapt your autofocus. First, you can choose from a grid of squares to set your focus point in different parts of the frame. It’s worth practising this, so that choosing a point becomes second nature as you shoot. Second, you can decide whether to use single or continuous autofocus (also known as AI Servo). Single autofocus will engage just once, then stop when it locks on to a point in the scene. As such, it’s good for stationary subjects. Continuous autofocus will instead keep adjusting the focus point continually as long as the autofocus button is engaged. This is suited to moving subjects, as the autofocus will track with the movement.
3 When to use manual focus
Despite momentous advancements in autofocus over the past few years there are still times when manual focusing is necessary. Autofocus may struggle in low light, so manual focus may be more successful for night photography and dim interiors. Then there are times when manual focusing may be more precise, like in macro photography or when shooting landscapes with a tripod. There are also times when manual focus mode can be useful simply for locking your focus point in place.
4 Focus on an edge or point of contrast
There are two autofocus systems used by digital cameras- contrast detection and phase detection. Contrast detection works by shifting the focus backwards and forwards until it detects sharpness in the image. Phase detection instead triangulates points in the scene to calculate the distance to the focus point. Whichever method your camera uses, it tends to lock on more successfully when you target a point of contrast - where a light edge meets a darker edge - than plain, uniform surfaces.
5 Aperture and focus
To properly understand focusing we also need to get to grips with depth of field. Whenever we focus on a point in a scene there will be a linear plane of sharpness that extends two thirds beyond, and one third in front of that point, with a gradual fall-off to softness. This area is our depth of field. As photographers one of the most important influences we have over our photos is depth-of-field. We can expand or contract it with our choice of aperture. Narrow apertures like f/16 result in a greater area of sharpness, which is why this is a good aperture for landscape photography (where the aim is usually to keep the whole scene in-focus). Wider apertures like f/2.8 result in very shallow focus, so anywhere in front or behind the point of focus will be soft.
6 When to pre-focus
Sometimes the object that you want to focus on will be passing through the frame so quickly that focusing while shooting is impossible. The solution is to pre-focus on a spot where you anticipate the action will take place, then wait until the object enters the frame. This technique is ideal for fast-moving subjects like a droplet of water or side-on motorsports action. It’s usually best to use a narrow aperture for greater depth of field, just in case your pre-focusing isn’t spot-on.
7 Use focus stacking
Focus stacking is brilliant for expanding the depth of field beyond the capabilities of your camera and lens. It’s an invaluable technique for macro photography, as when focusing on objects very close to the lens the maximum depth of field may only extend to a few millimetres. We simply use a tripod and take a series of shots while incrementally adjusting the focus point, until we have recorded sharpness across the subject or scene. Of course, the subject needs to stay still throughout. Then we use software to blend the frames together.
8 Animal tracking
Newer mirrorless cameras like the Canon R5, Sony a7 IV and Nikon Z9 have automated focus modes so good that it feels like cheating. These are capable of detecting eyes in human subjects as well as animals. One of the trickiest subjects to capture has always been birds in flight, but with new eye detection modes the technique is now much simpler. All you have to do is ensure the bird is in the frame, there’s no need to even think about whether the focus is right. The camera will do the rest.
9 Focus on the eyes
When photographing people it’s almost always best to focus on the eyes. If the eyes are soft, then the portrait will look plain wrong. When a person is side on then one eye will be closer to the camera than the other, and the plane of focus may not be enough to keep them both sharp. If this is the case then it’s best to focus on the eye closest to the camera. For groups, try to keep all the eyes on a similar plane of focus
10 Work out the hyperfocal distance
The hyperfocal distance is the closest point of focus at which the lens will achieve maximum depth of field. As such finding it can be useful when you want front-to-back sharpness in the scene, which is usually desirable for landscape photography. There’s an equation for calculating the hyperfocal distance: focal length x focal length / circle of confusion x f-stop (for simplicity, use an app or a chart to work it out with your phone).
For example, with a full frame camera fitted with a 28mm lens set to f/16 (an ideal aperture for maximising depth of field while curbing diffraction), the hyperfocal distance will be 1.66m from the camera, so we focus on a point roughly this distance away. As a quick alternative to all the maths, simply focus a third of the way into the scene.
James has been a professional photographer and award-winning journalist for the past 15 years. He is editor of Practical Photoshop magazine and contributes to leading photography publications worldwide.
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