sharp. When working at wide lens apertures where depth
of field is reduced, you must focus carefully to hold the
eyes, ears, and tip of the nose in focus. This is where a
good knowledge of your lenses comes in handy. Some
lenses have the majority of their depth of field behind the
point of focus; others have the majority of their depth of
field in front of the point of focus. You need to know how
your different lenses focus. Additionally, it is important to
check the depth of field with the lens stopped down to
your taking aperture, using your camera’s depth-of-field
preview control.
Your main focal point should always be the eyes, which
will also keep the lips (another frontal plane of the face)
in focus. The eyes are the region of greatest contrast in
the face. This make focusing simple, particularly for aut-
ofocus cameras that require areas of contrast on which to
focus.
When the subject’s face is at an angle to the camera,
the eyes are not parallel to the image plane. In this case,
you may have to split focus on the bridge of the nose to
keep both eyes sharp—particularly at wide lens apertures.
Focusing three-quarter or full-length portraits is gen-
erally easier because you are farther from the subject,
where depth of field is greater. Again, you should split
your focus halfway between the closest and farthest points
that you want sharp in the image. With these portraits, it
is still a good idea to work at wide lens apertures to keep
your background soft.
Autofocus.Autofocus, once unreliable and unpre-
dictable, is now extremely advanced. Some cameras fea-
ture multiple-area autofocus so that you can, with a touch
of a thumbwheel, change the active AF sensor area to dif-
ferent areas of the viewfinder (the center or outer quad-
rants). This allows you to “de-center” your images for
more dynamic compositions.
Autofocus and moving subjects used to be an almost
insurmountable problem. While you could predict the
rate of movement and focus accordingly, the earliest AF
systems could not. Now, however, almost all AF systems
use a form of predictive autofocus, meaning that the sys-
tem senses the speed and direction of the movement of
the main subject and reacts by tracking the focus of the
moving subject. This is an ideal feature for activity-based
portraits, where the subject’s movements can be highly
unpredictable.
A new addition to autofocus technology is dense
multi-sensor area AF, in which an array of AF sensor
zones (up to 45 at this writing) are densely packed within14 CHILDREN’S PORTRAIT PHOTOGRAPHY HANDBOOK
Autofocus, especially multi-zone autofocus, is an invaluable tool
in photographing kids who move quickly and unpredictably. Pho-
tograph by Suzette Nesire.
THE POPULARITY OF FAST ZOOM LENSES
With the advent of smaller image sensors, lens and camera manu-
facturers have the ability to more affordably design and manufac-
ture faster lenses. The preferred f-stop seems to be f/2.8. Slower
than that and photographers complain the viewfinder is too dim.
Faster than that and the lens is prohibitively expensive to make in
the zoom focal lengths. Thus the overwhelming popularity of the
70–200 and 80–200mm f/2.8 zoom lens. Both Canon and Nikon
make these focal lengths, and while still on the pricey side, they re-
ally perform. Both series of lenses use internal focusing, so the
length of the lens does not change in focusing/zooming. Internal
focusing also drastically enhances autofocusing speed. These lenses
use rare-earth lens elements in the design and can employ state-
of-the-art technology, including vibration reduction.