Canon EOS-1 Tips And Techniques page 21

General Purpose Combo
This isn't really a combination, except that we included C.Fn 17-1 as an option so it's
a little more reliable when you're using a single focusing point in poor lighting.
But, it is a very useful combination of settings because it gives more versatility to the
photographer.
Shooting AF Mode
Focus
Situation
Activation
Examples
button
General AI Servo or
photography One-Shot
Focus
Activation
with Shutter
release button
Background
Many photographers are more comfortable using the shutter release to initiate
autofocus, but some still want the ability to change focusing methods quickly.
This is very much like the Action Combo, but it's probably better suited to all-purpose
shooting; and it also lends itself to both One-Shot and AI Servo AF settings.
Operation
Decide how you will most often choose the focusing points (AFPS or Single Point AF).
Whichever method you will use less often, assign to the Assist Button as a HP. Then set
the more often used method using the AF Point Selection Button.
Photographers who use AFPS most of the time can set the HP to a single point (center
for those who might shoot some action, or off-center for those who shoot occasional
vertical portraits). Sports shooters could use a single point most of the time and register
AFPS as their HP for an alternative.
Shoot normally with your chosen focusing point selection method. While holding in the
Assist Button, you will have your pre-registered focusing point or AFPS. Let go and you're
back to your normal method.
Summary
Practice with these three combinations to get a feel for them. Trying these Custom
Function combinations will give you an idea of what some of the settings are capable of
I. CAMERA FEATURES AND OPERATION
C.Fn Set Function
18-2 While being pressed, changes the focusing
points or pattern that the camera uses to the
HP setting. Release and the camera defaults
to the method chosen by the photographer.
17-1 This expands the AF activation area if
(optional) needed in lowered contrast situations.
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