What is Continuous Autofocus?
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There are so many modes and settings on our digital cameras, but some, such as continuous autofocus, are considered basic controls and are generally very easily accessed from a dial, switch, or button.
What is continuous autofocus and how simple is it to learn when and how to use continuous autofocus?
What Exactly is Continuous Autofocus?
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Continuous autofocus is a mode affecting how your camera takes pictures while using the autofocus.
On some DSLR and mirrorless cameras, it is labeled by a dedicated switch, dial, or button on the top of the camera, though some may place it on the back. Either way, it’s a control that will generally be easy to find without needing to use the camera menu.
Single shot autofocus, AF-S, prevents the camera shutter from firing unless the focus is confirmed. Continuous autofocus, AF-C, allows the shutter to be released without a firm lock or confirmation of focus.
It essentially acts like a servo, continuously varying the focus as needed, in fact, some brands even call it Servo AF or something similar.
How to Set Continuous Autofocus
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With almost any camera we have, DSLR, mirrorless, entry-level, prosumer, or full-fledged professional, the control for changing between single shot and continuous autofocus will be very obvious, once we know what control to look for.
For Canon continuous autofocus, look for the control Servo AF or Servo AI AF. Canon calls their camera being ready to focus when pressing on the shutter release continuous autofocus, which is accessed by a menu setting, so look for a top plate button control to be labeled Servo AF.
I really wish everyone would standardize on terms, but branding is important for camera manufacturers, too.
Nikon continuous autofocus is often accessed by a rotary switch that may be on the body near the lens mount or on the top plate of the camera sandwiched in with some other controls. Look for AF-C to set continuous autofocus.
Sony, Fujifilm, Pentax, Olympus, Panasonic will be similar to Canon and Nikon, but in slightly different areas or with a unique but simple name. The simple fold out flyer of basic controls that came with the camera should show it as one of the first controls listed.
We should note that the camera menu can be used to control which focus mode is set and how they work, so make sure to familiarize yourself with the specifics of your personal camera.
When and Why to Use Continuous Autofocus
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A question that comes up a lot about continuous autofocus is why use it at all since we want accurately focussed images. The answer is in how the camera fires the shutter. For single shot autofocus, the sensor must confirm AF before the shutter is allowed to fire.
In continuous autofocus mode, we can release the shutter regardless of focus confirmation. This does not mean that our images will be out of focus, but rather that the AF continues to operate as we keep shooting.
While this may result in some out-of-focus images, the majority of our images will be perfectly focused since the camera continues to adjust focus. This is a good setting for any action photography.
The idea is that continuous autofocus allows us to track the action in the camera viewfinder, letting us fire the shutter without the camera lagging due to focus confirmation. We still have to set what focus points and use subject techniques for best results.
Sports photography immediately comes to mind, but continuous autofocus is also an excellent choice for wildlife photography and casual outing with family and friends.
As a basic camera control option, learning how to use continuous autofocus will improve our photography in general as well as in some specific situations.
