Canon EOS DIGITAL REBEL XTI Service Manual page 78

・Two-line focusing with the center AF point's horizontal-line sensitive sensor at f/5.6
The center AF point's horizontal-line sensitive sensor for f/5.6 has a two-line,
zigzag pattern. By having redundant focusing, the focusing detection becomes more
consistent.
・Improved AF precision with fine-tuning
As with the EOS 30D, fine-tuning has been incorporated to improve the AF precision.
⑵Improved performance under low light
The focusing performance under low light has been improved by 1 stop. Focusing is
now possible within EV -0.5 to EV 18.
⑶Wider focusing area
・ Diagonal configuration of AF points (in and around the prime area (golden section)).
・Improved subject focus tracking with nine AF points.
２）AF speed and calculation
As with the EOS 30D, a high-performance, 32-bit RISC microcomputer is used for high-
speed processing. It executes preceding AF processing, and the SI display and focusing at
the same time as the lens driving and reflex mirror action. The AF speed is therefore on par
with the EOS 30D.
The algorithm for AI SERVO AF continuous shooting has been fine-tuned and optimized
to attain 3 fps.
３）AF mode
In the Creative Zone modes, the following AF modes can
be selected: One-Shot AF, AI Focus AF, and AI SERVO AF (Fig.
014). In the Basic Zone modes, the optimum AF mode is
selected automatically.
In the Sports, Flash Off, and Basic Zone's Full Auto modes,
the beeper sounds softly (with the beeper enabled) while
focus is achieved with AI SERVO AF.
＊ In the Creative Zone modes with AI SERVO AF, the beeper does not sound
while focus is achieved.
＊ The AF mode can be set even while the lens focus mode switch is set to
MF. However, "MF" will be displayed on the LCD monitor when it displays
the camera settings.
Fig. 014 AF mode selection
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Technical Information
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