Do you sometimes wonder why your photos have turned out blurry or out of focus? It could be that you are using the wrong aperture or shutter speed, or it could be your choice of focusing mode. Here we look at the main focusing modes you're likely to find on your camera, and when to use each one to get the best results and more images which are correctly-focused.
When trying to understand what different focusing modes are for, it's important to have a basic grasp of exactly what focus is in terms of photography. Focusing is the process of controlling the area of an image which is "sharp" by making adjustments to the lens. The depth of this focus area can be adjusted by changing the aperture, but can also be moved backwards and forwards using manual or autofocus modes to move lens elements.
Autofocus points and areas
Before we look at the main focusing modes, it's important to recognize how other focus settings, such as AF point/area selection, also come into play. AF points are positions in the frame which can be used to measure the distance to a subject, so that the lens can be focused to that point. In a fully automatic autofocus mode the camera would use all of these to identify a subject and focus on that as the shutter button is pressed, just like a point-and-shoot cameras.
However, there are (thankfully) other autofocus area modes which give the photographer more control. These allow them to select what point in the frame should be in focus by selecting an AF point, of which there could be anywhere between one and hundreds to choose from. This is typically done via a button or joystick on the rear of the camera, or tapping a rear touchscreen.
Depending on the subject being photographed, and whether it's moving, users can also adjust which AF points are available to the AF system. Options here include things like Group, Dynamic, Zone or 3D/Tracking, which each adjust the active AF Area, and how the system responds. We'll look at these autofocus area options in a bit more detail in a later article, but for now we'll focus on the main focusing modes.
Single (AF-S/One-shot)
In this focusing mode the camera will automatically focus on a subject as you begin to press the shutter button and then lock at that focus point until the button is released. Users have the option of focusing at the center of the frame, or choosing one of the other focus points within the autofocus system to select their subject.
When shooting in single focusing mode, if you want to focus on a subject which doesn't line up with an AF point, you can focus on it with a half press of the shutter, and then move the camera slightly to recompose the composition before fully pressing the shutter button. A handy feature can be the confirmation notification (either a beep or a light) to tell you when the subject is in focus.
This mode is best used when shooting mostly static subjects such as portraits, landscapes and still life. One thing to note is that autofocus can be hit or miss in lower light situations, though newer cameras are far better in this regard than those from just a few years ago.
Continuous (AF-C/AI-Servo)
Continuous AF should not to be confused with continuous/burst shooting modes, though it will often be used in conjunction with them. Instead, this mode allows users to lock focus on a specific subject and it automatically adjusts as that subject moves either towards or away from the lens. As the shutter button is half-pressed the focus will constantly adjust, compared to single focusing which locked the focus at this point.
Because of this you'll also want to consider which focus points the camera is set to use. Use of AF point groups or zones rather than a single AF point will enhance your camera's ability to track a subject if it is moving across the frame and not just forwards of backwards. Another thing to remember is that by default this mode will typically let you take photos even if the subject isn't in focus, though on many cameras you can set a priority between shutter and focus, depending on what you're shooting.
As you might expect, this mode is well suited to shooting subjects in motion that would otherwise be moving in and out of focus. However, it's not a case of always switching to Continuous AF if your subject is moving. If you want a photo of a moving subject in a certain location, you might be better served by using single or manual focus along with burst shooting.
Manual Focusing
The traditional method of focusing, and still used by many photographers, manual focusing leaves the photographer in ultimate control of what's in focus. This is typically done by rotating a lens-ring around the barrel of a lens one way or the other to move the area of focus either further from, or closer to, the lens.
Because the photographer is in control of the area that will be in focus, it's important that they can make an informed decision before hitting the shutter button. This can be done by working off a distance measure, or by viewing the scene via a viewfinder or monitor. Features like focus peaking (which highlights edges of focus) or zooming in on the rear monitor for a better view, can be helpful for guaranteeing sharp focus in manual mode.
Examples of times you might be best served by manual focusing include when shooting in low light situations where autofocus can struggle, close-up macro work and when shooting through something like a window, autofocus can often focus on the glass rather than your intended subject.
Summary
Hopefully this article has given you a bit more confidence to select the right focus mode for the job. You might find that switching to continuous focusing helps you nail focus in some shots which could have otherwise ended up out of focus. In an upcoming article we'll also look in more detail at how to use those different AF area settings in conjunction with these focusing modes.
You might want to check out our previous guides to getting out of auto, such as our guide to the buttons and modes on your camera, aperture, shutter speed, ISO and the exposure triangle.
