When we talk about using the aperture to control depth of field during our Photo Walks, Classes and Workshops, we specify focusing on a particular point in your composition. The depth of field extends in front of and behind that point.
Not too surprisingly, many of you who are just learning your camera are not familiar with setting it up so that you control what the camera focuses on!
Left on its own at the default settings, with all focus points active, the camera is programmed to focus on the closest object it finds in the frame. This is not always where you want to focus.
You do have a way to select a specific focus point. As usual, how you do this differs from camera brand to camera brand (and sometimes model).
On all Canon SLRs that I’ve used this is done by pressing the far right button on the upper back of the body. Canon amazingly calls this the “AF Point Selection” button – mark the day, this may be the only time you find anything described that clearly!
You’ll need to half-press the shutter to activate the meter – to “wake up” the camera – first. When you press the AF point selection button you’ll see all focus points lighted in the viewfinder and on some models also displayed on the LCD screen. You then use the front control wheel to move through the focus points to select the one you want.
On Nikons, (sigh) it depends. On most models you go into the Menu, to AF Area Mode and select Single Point. Then use the Multi-Selector (up, down, right and left arrows on the back) to move the focus point to the desired position. (Note- some Canons allow you to do this as well as select with the front control wheel.) If this doesn’t work for your model it’s time to look in the manual.
For other brands, Sony seems to mostly follow Nikon’s arrangement, Pentax follows Canon’s and the others – well, this is again the time to “go to the book”. We’ve all agreed that the camera manual is not ideally read like a novel. But it is useful as a reference when you know what you’re looking for.
How many options of points you have will depend on the model camera you are using. Typically the higher-end (as in, more expensive) the model, the more points you’ll have available.
For most shooting it isn’t critical which one you select as you can still half-press to focus and then re-compose. I usually use the center point unless I know I’ll be regularly looking in a particular part of the frame. The idea is you now have control over where the camera focuses by placing that point on your subject.
Of course all of the above applies to SLRs. The many point & shoots, advanced digitals and now the mirror-less interchangeable-lens models all have their own language. Some point & shoots don’t have the option to select the focus point, others do. Pretty much all the advanced digitals and MIL models have it. Again you’ll want to see your manual for your particular model.
While there are always exceptions and for some types of fast-moving subjects having all focus points active can be desirable, for most day-to-day walk around photography I recommend always having a single focus point active, allowing you to put the focus exactly where you want it.
Hope this helps make things clearer. (Don’t you really miss my bad puns during the off season?) See you on the next Photo Walk!
– Stu Estler