UNDERSTANDING
SINGLE, DYNAMIC, AND GROUP AUTOFOCUS SETTINGS (b)
GROUP
DYNAMIC AUTOFOCUS
With
Group Dynamic AF, you’ll select the sensor you
want to use and the D2x will use it as the primary focus
sensor. It’s somewhat similar to Single Area AF,
except that the immediately surrounding sensors are
also active. This allows some erratic movement from
your subject, as long as the movement is not too large. |
|
You
can move the cross-shaped group of sensor groupings around
with the thumb toggle switch.
| In
figure 9 we see another simplified image of the focus
area in use. Dynamic Area AF, and the center AF sensor
is selected: (see page 77 of manual). |
|
This
works a lot like Dynamic Area AF, except that the active sensors
are in a movable cross shaped pattern. This mode is best for
erratically moving subjects that do not move very far. Maybe
you are shooting an ant crawling around on a flower. He keeps
moving, but your camera is bolted down to the tripod. This
allows the camera to keep close focus on a small area, while
allowing the subject to move around within that area.
Many
sports photographers use this mode for sports shooting. It
allows an area around the primary focus point to stay active,
which helps track a moving person, but not all AF sensors
are in use which might tend to pull the autofocus to another
unintended person moving nearby.
There
is another custom setting in the D2x that applies directly
to this mode. Custom Setting
a3 modifies how your Group Dynamic AF works. This
setting allows you to be very precise in using individual
groups of AF sensors by using selectable “sensor patterns.”
In figure 10 below, we see a series of pictures of the menu
screens used to set a3:
In figure 11 let’s examine Custom Setting
a3’s patterns. First let’s look at Pattern 1 and
discuss how it works:
In
figure 11, pattern 1 at left has a cross-shaped arrangement.
The center AF sensor is providing primary initial focus (sensor
in red), while the surrounding sensors (see + signs) are active
and awaiting the subject’s movement. If the subject
moves out from under the center sensor, the surrounding sensors
will track the focus. You’ll not be able to see which
sensor is actually tracking the focus when your subject leaves
the sensor you first started using. It would be nice if Nikon
turned the sensor red as a new sensor starts detecting focus,
but that’s not the way it works in this camera. This
is the factory default setting for the D2x in Group Dynamic
AF mode.
The
second pattern, at right in Figure 11, shows the Closest Subject
focus arrangement. It is exactly the same as in Center Focus,
except that ALL the sensors in red are used together. You
will not be able to select or determine which sensor is initially
providing focus, or which is tracking focus. The camera focuses
on the closest subject with enough contrast to provide a good
focus.
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