Manual focus: what you need to know to get sharp images
Your DSLR has comes with a highly advanced autofocus system, so why on earth would you want to use manual focus? Actually there are some very good reasons – various subjects and environmental conditions either fool the camera, or make it considerably harder to get a good shot in autofocus mode.
The AF sensor in your digital camera needs certain things to perform well, and at the top of the list is light and contrast. It uses edges or textures to focus on areas of contrast. If you’re shooting in low-light, AF can have problems seeing subtle, indistinct features.
If contrast is low, as in misty conditions or when aiming at smooth water or wet sand, your camera’s AF circuitry has difficulty locking onto the subject. Manual focus, then, helps you get sharp shots when AF can’t correctly interpret what the lens is seeing.
Another set of AF issues occurs when the camera focuses on the wrong thing. Shooting through a wire fence or a glass window, for example, can cause focusing problems in AF mode because the camera focuses on the obstruction, rather than the subject beyond it, and likewise it can be particularly challenging to get good nature shots through branches, leaves or long grass.
Your camera will always focus on the closest thing the sensor sees, and this can cause problems when shooting a particular animal, when another one flies or walks through the frame and distracts the AF. So switch to manual focus when you know your camera could get confused.
The final set of conditions where you’re better off focusing manually is to do with speed: either because the subject is moving so quickly that it’s hard for the camera to focus in time, or the slight delay of hunting to achieve focus is long enough to miss the shot.
When shooting racing cars on a bend, for instance, it’s often better to pre-focus on a particular spot on the track in AF, then lock your focus in MF, and wait for a fast-moving car to reach that spot before taking your shot.
The same principle applies in nature photography, where pre-focusing on a perch allows you to prepare for a bird’s landing or take off to get a crisp action shot without AF delay, or even when photographing your children in the park.
Shooting situations where manual focus is best
When shooting through foliage or grass, manual focus and a wide aperture reduces the foreground to a pleasing colourful blur (confused about aperture – download our Free f-stop chart to master your aperture).
With fast subjects like this, it’s best to pre-focus on a particular spot and, when the subject reaches that mark, fire the shutter.
If you autofocus on the horizon, you’ll waste much of your depth of field. For more on how to focus for this type of image, see the cheat sheet on calculating hyperfocal distance below (or you can check out our tutorial What is hyperfocal distance: 6 tips for sharper landscapes).
When you want to combine a series of shots into a panorama or an HDR image, manual focus is absolutely essential to ensure that the focus doesn’t change between images.
Main manual focus controls
To help you – literally – get to grips with the manual focus controls on your DSLR, we put together the photography cheat sheet below, which illustrates where to find some of your most useful buttons. Feel free to drag and drop this infographic on to your desktop to save as a reference or print out and stash in your camera bag.
PAGE 2: Using manual focus in Live View; camera assisted manual focus; focusing for macro
PAGE 3: How to calculate hyperfocal distance; final tips on using manual focus
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on Thursday, May 3rd, 2012 at 11:51 am under Photography Tutorials, Tutorials.
Tags: camera tips, DSLR tips, hot, landscape photography, macro photography, manual mode, photography cheat sheet