Canon EOS 20D Instruction Manual

Page of 168
SSelecting the AF PointN
68
 
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Press the <
S> and turn the <6>
or <
5> dial.
 
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When you turn the dial, the selection will go 
in the looping sequence shown on the left.
Under low-light conditions, the built-in flash fires a brief burst of flashes 
when you press the shutter button halfway. This is to illuminate the 
subject to enable easier autofocusing.
The EOS 20D will execute high-precision AF with lenses whose 
maximum aperture is f/2.8 or larger.
With lenses whose maximum aperture is f/2.8 or larger
With the center AF point, high-precision, cross-type AF sensitive to both 
vertical and horizontal lines is possible. With cross-type AF, vertical-line 
detection is twice as sensitive as horizontal-line detection. The other 
eight AF points are horizontal-line sensitive or vertical-line sensitive.
With lenses whose maximum aperture is larger than f/5.6
The center AF point is a cross-type AF sensor. The other eight AF 
points are horizontal-line sensitive or vertical-line sensitive.
Selecting with the Dial
AF-Assist beam with the Built-in Flash
Lens’ Maximum Aperture and AF Sensitivity
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When looking at the LCD panel to select the AF point, note the following:
Automatic selection 
, center 
, right 
top
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If focus cannot be achieved with an EOS-dedicated, external Speedlite’s 
AF-assist beam, select the center AF point.
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In the <
3> <5> <7> modes, the AF-assist beam does not light.
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The built-in flash’s AF-assist beam is effective up to about 4 meters/13.2 feet.
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In the Creative Zone modes when the built-in flash is popped up with the 
<I> button, the AF-assist beam will be emitted if necessary.