71
Using Autofocus (AF)
3
AF Sensitivity and the Lens’ Maximum Aperture
The EOS-1D’s AF points are all horizontal-line sensitive. However, bright lenses
with a large maximum aperture enable certain AF points to work as cross-type
sensors for higher AF precision.
(1) With lenses whose maximum aperture is f/2.8 or faster
(lower f/number), the AF points highlighted in the illustration
will be cross-type sensors sensitive to both vertical and
horizontal lines. The remaining 38 AF points will only be
horizontal-line sensitive. The cross-type sensor’s vertical-
line sensitivity is three times higher than the horizontal-line
sensitivity.
(2) With the following L-series lenses whose maximum
aperture is brighter than f/4 by lens only or with Extenders,
the center AF point will be a cross-type sensor for high-
precision AF. The remaining 44 focusing points will only be
horizontal-line sensitive (except with EF 70-200mm f/2.8L
USM + Extender EF 1.4x).
EF 28-80mm f/2.8-4L USM
EF 300mm f/4L USM
EF 300mm f/4L IS USM
EF 400mm f/4 DO IS USM
EF 500mm f/4L IS USM
EF 600mm f/4L USM
EF 600mm f/4L IS USM
EF 70-200mm f/4L USM
•
With Extender EF 1.4x or EF 1.4x II:
EF 200mm f/2.8L USM
EF 200mm f/2.8L II USM
EF 300mm f/2.8L USM
EF 300mm f/2.8L IS USM
EF 400mm f/2.8L USM
EF 400mm f/2.8L II USM
EF 400mm f/2.8L IS USM
EF 70-200mm f/2.8L IS USM
•
With Extender EF 2x or EF 2x II:
EF 135mm f/2L USM
EF 200mm f/1.8L USM
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