Canon 30D - Manual (Page 13)

Page 13 of 35 © Ken Rockwell 2006
Unmarked Button above Big Dial: This is a 9-way navigation button. You
can push it in 8 directions, or push it straight in.
In playback it lets you scroll around the image after zooming in. It ignores you
if you're not zoomed in, or are in the multi-image playback mode.
In shooting it ignores you, unless you first press the top-right
[+] button
(explained below). After pressing the [+] button, the unmarked button allows
you to select the autofocus sensor, which you'll see highlighted in red in the
finder. You'll also see a cryptic [ - ] display on the top LCD, which is a
rough representation of the selected AF sensor.
Move the unmarked button to select the AF sensor. Push the unmarked
button straight in to select the center sensor, which is very handy. Push it
straight in again to light all the sensors, which lets the 30D select the sensor
automatically.
This button has nine direct positions and selects that sensor directly,
regardless of the currently selected sensor. Unlike Nikon, it doesn't move the
selection around by clicks.
Example 1: if you have the bottom sensor selected and want to select the
lower left sensor, just press the button to the lower left. Pressing it to the
upper left, as you'd do on Nikon to move it a click, would select the upper left
sensor.
Example 2: if you have the right sensor selected and push the button left,
you'll get the left sensor directly. You won't move a click to the center sensor
as you would on Nikon. You get the center sensor by pushing the button
straight in.
You can let the unmarked button move the AF sensor without needing to
press the [+] button first in Custom Function 13.