Should you use autofocus or manual focus? The truth is, there are times when one or the other is more advantageous. In this quick guide we explain when to use manual focus, and when to avoid it.
Before autofocus came along, the only way to get a subject sharp was to focus manually. It didn’t matter what you were shooting, a motionless landscape or a fast moving car, the focusing was done manually. Today we have a choice, we can focus automatically or manually. Although it’s still possible to get most subjects sharp when focusing manually, autofocusing usually makes life much easier and gets the subject much sharp easily.
However, there are a few occasions when manual focus mode is the best choice. There are also times when it’s best to avoid manual focus mode altogether. Let’s take a look.
The speed and accuracy of most AF systems make autofocusing the obvious choice for most still photography. Manual focus mode tends to be a fall-back option that’s used in situations in which an AF system is likely to waver or fail; read-on to find out more about these.
If you’re shooting with an SLR on a tripod and composing the image on the main screen in Live View mode, it’s often better to focus manually rather than automatically. This is partly because many SLRs employ a slow contrast detection autofocus (AF) system, but also because Live View mode lets you magnify the most important section of the scene so that you can make sure that the focus is at exactly the right place.
If you’re focusing manually with an SLR, we recommend using Live View mode whenever possible as it allows a much more detailed view of the subject than an optical view finder.
Even though the mounted optic may offer very close focusing, many cameras struggle to focus a lens if the subject it very near. This can lead to hunting, when the lens shifts the focus point backwards and forwards trying to lock-on, or missed focus when the lens is focused at the wrong point. As a result manual focusing is a good option for macro subjects.
The magnified view offered in compact camera systems in manual focus mode, and DSLRs in Live View mode, is extremely useful because depth of field is very limited with short focusing distances so it’s absolutely vital to get the focusing spot-on.
Although there are cameras with tens of autofocus points there often isn’t one exactly where you need it. In some cases it makes sense to use the ‘focus-and-recompose’ technique, but if you’re shooting a landscape manual focus is a good option.
If the light is changing quickly you may need to act quickly, but you usually have a bit of time with landscape photography and it’s often a good idea to slow down a bit and give the composition and focus point proper consideration.
Focusing manually slows you down, but more importantly it enables you to place the focus at exactly the right distance to get the depth of field that you want.
Low light and contrast
Autofocus systems need some light and contrast to operate, so they can fail in low light and/or low contrast situations. These conditions can also make focusing manually tricky, but if you have a compact system camera or your shooting with an SLR in Live View mode, the screen or electronic viewfinder can often enhance its image enough to allow you to get the subject sharp.
Objects between the camera and the subject
If your camera has clear view of the subject, the light is decent and there’s a bit of contrast, the autofocus system will usually deliver the goods and you’ll get a sharp image. What’s more, a camera can usually get a subject sharp more quickly than you can manually.
However, if there are objects between the camera and the subject, perhaps you’re shooting through moving foliage, the autofocus system has no way of knowing which is your intended target and it’s likely to focus on the nearer object.
The easiest way to get around this problem is to focus manually on your subject. If you do this it won’t matter what the objects in the foreground do, they can pass right across the centre of the lens, the camera will not adjust the focus.
Sport and action
Although it is possible to get moving subjects sharp when you’re focusing manually, it’s usually far better to use the cameras’s AF system – especially with subjects that move unpredictably.
Rather than using Single AF mode, Continuous AF mode is the best choice for shooting moving subjects because the camera will continuously adjust the focus of the lens as the subject under the active AF point moves towards or away from the camera.
That said, when a subject is moving in a predictable direction it can be helpful to prefocus the lens (manually) at a particular point and wait for the subject to arrive at it before taking the shot. The advantage of this approach is that it avoids any delays caused by the AF system and allows you to pick the image composition before the subject is in place.
If you’re not continuously focusing there will only be a short window during which the subject is sharp, so even if you’re shooting in continuous drive mode you’ll only get a few shots so you’ll have fewer images to sort through and process.
Although most manufacturers are working hard to improve autofocusing during video recording, most professional videographers only every use manual focus mode. The main reasons for this are to avoid hunting or focus errors from being recorded.
Many also want to dictate the speed of focus transitions and ensure that changes are made smoothly. While this can be achieved by rotating a manual focus ring by hand, there are focus pulling devices that can be used to smoothly rotate a ring from one specific point to another.