Canon EOS 5D Mark II - EOS 5D Mark II 21.1MP Full Frame CMOS Digital SLR..., Service Manual

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Technical Information
7
In other words, the center AF point's vertical line-sensitive sensor has two types, one
for f/2.8 and another for f/5.6. It enables cross-type focusing at the center with any EF
lens.
⑵Outstanding AI SERVO AF subject tracking
Above and below the center AF point, are a
total of six invisible Assist AF points (Fig. 014).
They do an excellent job of tracking the subject
in the AI SERVO AF mode as described below.
All six Assist AF points are f/5.6-sensitive. Two
of them ■ are also f/2.8-sensitive when a lens
brighter than f/2.8 is used. They use the f/2.8
light flux to detect the focus.＊
＊
Except with the EF50mm f/2.5 MACRO and EF28-80mm
f/2.8-4L USM.
・ Wide-area, automatically-selected, 15-point AI SERVO AF
In the AI SERVO AF mode and automatic AF point selection set, a total of 15 AF
points, including the six Assist AF points, will automatically function. This enhances
the subject tracking performance and enables a smoother transition from the center
AF point to adjacent AF points. As with previous cameras, the focusing starts with the
center AF point, and if it cannot track the subject, the other AF points will help to track
it.
・ AI SERVO AF with 7 automatically-selected AF points at center
With C.Fn-17-1 "AF point activation area", AI SERVO AF, and the center AF point,
subject tracking at the center is enhanced with seven AF points including the Assist AF
points.
⑶Intermediate AF points for superb focusing detection precision
Since the four f/5.6-sensitive, intermediate, vertical sensors have a long base line, the
focusing detection is more precise. The left and right AF points have the same base line
length as f/5.6-sensitive sensors in previous cameras.
２）AF unit
⑴Configuration of focusing optics
Fig. 015 shows the configuration of the
focusing optics. After passing through the
lens, the 19 (11 vertical and 8 horizontal)
by 38 light flux are sampled individually.
The image-formed on the primary image-
formation surface (image plane) goes
through the secondary image-formation lens
for each focusing area before it forms again
on the AF sensor. Six horizontal light flux at
the center are set for f/2.8 for focusing. The
other 32 light flux are set for f/5.6 (same
as the focusing light flux of previous EOS
cameras).
:
Sensitive to f/5.6
Assist AF points
:
Sensitive to f/2.8
Assist AF points
Intermediate
AF points
Fig. 014 Assist AF points
Field lens
Primary image-
formation lens
Secondary image-
formation lens
AF sensor
Fig. 015 Focusing optics