focus mode

Photography Tip - use a single focus point for moving subjects not filling the frame

There are a number of reasons why a moving subject may appear out of focus in a photograph.  One reason could simply be because the focus point(s) were not on the subject.  For still subjects, I always use a single focus point.  For moving subjects where the subject is not largely filling the frame, even in the examples above of runners, I use a single focus point as well.  By using a single focus point (in the center) when photographing the runners I could track them as they ran past me and I knew for sure that I was getting them in focus because the only focus point available was right on them.  There was no risk of back-focusing on the background which can happen when using multiple focus points (11, 21, 51, etc).  In this case, I did not want the camera trying to pick out the subject from the background which is what happens when using multiple focus points.  I selected a single focus point, kept it center, and kept that locked onto each runner.  Of course I was using AF-C (One Shot) focus mode and a minimum shutter speed of 1/500th--the other two things needed to have any chance at freezing of moving subject in a photograph.

So if you find you are having trouble getting a moving subject in focus (or even a still subject), use a single focus point (often in the center) and put it right on the subject you want to be in focus in the frame.  

Portrait Photograph Tip - set the focus on the eyes

When making a portrait, set the focus on the eyes, then recompose.I always use a single focus point when photographing still subjects.  Most of the time I keep that single focus point in the center, and the recompose how I want the final image to look.  Of course for shooting still subjects I use AF-S (one shot) focus mode.  So when making portraits using the settings described previously, I set the focus on the subject's eyes, then recompose because the most important thing with a portrait is getting the eyes in focus.  

Very rarely do I center subjects, and in a portrait the eyes of the subject are not very likely to end up perfectly centered as well.  In the above shot I first put my center focus point on the subject's eyes, then recomposed to put her eyes in the upper third of the frame (also her right eye ends exactly at the right horizontal third).

So when making portraits, set the focus on the eyes, then recompose how you like.

Focus Mode AF-S or AF-C photography tip

One of the five things you need to know how to set correctly to make a well exposed and sharp shot in any given shooting conditions is focus mode.  Fortunately, focus mode is by far the easiest of those five settings to set as there are only two choices (disregarding manual focus mode):

  • AF-S (One Shot - Canon) for still subjects
  • AF-C (Ai Servo - Canon) for moving subjects

That is all there is to choosing which focus mode to use.  Is the subject moving or not?  In the above example the chainlocked bike certainly is not moving so I used AF-S to shoot it.  In the other example the triathlon cyclist was definitely moving, and fast, so I used AF-C.  

Most DSLRs offer a third, and useless, kind of auto auto-focus setting that you should just pretend does not even exist!

So there is no reason to ever make a focus mode mistake if you can just remember AF-S (think "S" for still subjects") and AF-C (think "C" for continuous, moving subjects).  No matter what you make a photograph of, moving or still, now you know which focus mode to use!