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74 Quick Guide for the Impatient User

green dot in the lower left-hand corner). But pointing that small rectangle
toward ANYTHING that has contrast – a horizontal or a vertical line for
example – it zeros in on it like an eagle zeros in on its prey.

Notice that in this example, the center focus point can focus on horizontal
OR vertical contrast. Not all the focus points can do that. To see what I
mean, let’s change the focus area to MENU  3  Focus Area 
Flexible Spot. This works identically to the CENTER setting we just
used, except you can actually move that focus point around via the joystick.

So let’s move it around. Starting from the center, move the focus point one
unit to the left and one unit down. Notice that the focus point can find
horizontal contrast, but it can’t find focus when you shot it vertical
contrast!
This is the meaning of the term “Crosspoint sensors” – it means that the
focus point can detect both vertical and horizontal contrast (i.e., the sensors
are oriented 90 degrees to each other, looking like a cross.) Crosspoint
sensors are considered essential in shooting sports, but the’re also more
difficult to manufacture, and so Sony has spread the crosspoint sensors only
in the area where you’re most likely to use them, in the center cluster. The
red squares in Figure 3-6 shows where the crosspoint sensors exist. All
others can detect horizontal
contrast only.

So that’s how a single focus
point works. Now let’s set
the focus area to MENU 
3  Focus Area 
Wide. This turns on all 79
focus points, which you can
see in the Live View screen.
So with all of these focus
points enabled, how on earth
Figure 3-6: Not all focus points are created does the camera decide
equal! The ones in red can sense contrast in
both the vertical and horizontal direction; which one to use for
whereas the black can sense horizontal focusing? The camera can
contrast only. The green square in the center guess pretty accurately using
is optimized for lenses of f/2.8 or faster. the following method: The

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