Every October, we take the grandchildren to a local farm that has been converted to a children's playground. The farm is crawling with all kinds of linoleum lizards, all of them running, hollering, dancing, and just generally goofing off. They've got monster slides, hayrides, and, to keep things more pleasant, they have farm animals to cover the little kid smell. There are many fun things to photograph. As usual, you need to think about your subject matter and set up your camera properly. Today's digital SLRs can focus manually, to allow you to adjust the specific focus you want. The autofocus can be set to focus once (partially depress your release button) or continuously. Use the single focus for static subjects like landscapes and portraits. To capture images of those hyper-active monsters on the run, you're going to need a fast shutter speed and a continuous focus mode.
This setting is called different things on different cameras: Nikon, continuous focus; Canon, AI servo; and the action setting on most point and shoots. When this setting is enabled, your camera will maintain focus on the subject in the focus point you select, even as the subject moves.
You have to keep your autofocus point on the subject; this is crucial. Here is what happens if you miss it:
This shot is 1/800 of a second, so that is certainly fast enough to stop the motion of a rope-swinging five-year-old. The aperture is f5.3, so the depth of field is not too shallow. Everything in the background is crispy sharp. The problem is clear - the autofocus point is not on Grace.
As soon as I saw the LCD, I realized I was in single mode and shifted it to continuous. You can see the results on her next swing as I caught her release from the rope.
With the continuous autofocus on, I was set for the day. Here Jenipher and Rebecca come out of the shadows and immediately into focus. The famous big slide race is in focus, with Andy and Grace leading Cathy and Drew.
Most of today's cameras are much faster than the manual focus we used in the days of film. The most important thing is to know how your autofocus points work. Then you need only line up your subject for in focus photos.
Following moving objects is more challenging than focus on a landscape, but the rocks don't give you hugs at the end of a fun day. We all had a great time. Jenipher used my camera to catch me at the end of a harrowing slide ride. The continuous autofocus ensured she caught me in focus.