Master your camera’s autofocus: which AF points to use and when to use them
Using autofocus correctly can solve a great number of the common photography problems you face on a daily basis. But easier said than done, right? Behold the bible on AF points!
In this tutorial we’ll show you everything you need to know to take control of your AF points and nail focus every time you shoot.
Focusing has never been so simple. Use any of the Basic Zone shooting modes – Full Auto, Portrait or Landscape – and your camera does all the work for you. It’s almost too easy.
A light press on the shutter button is all you need and, 99 times out of a 100, the camera will focus in a split-second and you’re ready to fire.
So why is it that many shots simply aren’t sharp in the places that matter, such as the eyes in a portrait or the rolling hills of a landscape? The answer lies in the way that the autofocus system actually works.
Left to its own devices, a typical mid-range DSLR uses all of its nine autofocus sensors, which are spread out in a wide array around the image frame.
There’s one AF point at the centre, one both above and below it, another two to the left and right, and a final pair positioned towards the extreme left and right sides of the frame.
More advanced cameras feature an additional six ‘AF Assist’ points, although these, unlike the first nine, can’t be selected manually.
Near and far
To achieve autofocus in your camera’s shooting modes your camera uses information from all nine
It works out the distance of each part of the scene from the camera, chooses the closest object that coincides with an AF point and locks the autofocus at that setting.
This is fine if you want to focus on the nearest object in a scene, but often that’s not the case.
If you’re shooting a sweeping landscape, for example, you don’t want to focus on the grass in the foreground.
In these cases it’s better to select a Manual AF point. And in close-up or telephoto photography, especially with a large, wide aperture that reduces the depth of field, pinpoint accuracy becomes even more critical.
PAGE 1: What your camera’s autofocus points can do for you
PAGE 2: Making the most of your range of AF points
PAGE 3: When to use your different AF points
PAGE 4: How to choose the best AF point
PAGE 5: How to fool your autofocus – and why you should do it
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Getting sharp images: every photo technique you need to know starting out
on Thursday, February 7th, 2013 at 4:42 pm under Photography Tips.
Tags: camera tips, How to focus