Canon EOS-3 manual AF Sensitivity and the Lens’ Maximum Aperture

●AF Sensitivity and the Lens’ Maximum Aperture

The EOS-3’s AF sensitivity in relation to the lens’ maximum aperture is described below.

The EOS-3’s focusing points are all sensitive to horizontal lines. However, depending on the maximum aperture of the lens, certain focusing points can also be sensitive to vertical lines to enhance AF precision.

(1) With lenses whose maximum aperture is f/2.8 or larger, the focusing points highlighted in the figure become cross sensors sensitive to both vertical and horizontal lines. The remaining 38 focusing points are horizontal-line sensitive. Cross sensors (also used as the center focusing point in the EOS-1 and EOS-1N) attain higher AF performance and precision. The sensor’s vertical-line sensitivity is three times higher than horizontal-line sensitivity.

(2) With the following lenses whose maximum aperture is f/2.8 to f/4, high-precision AF is possible with the center focusing point which works as a cross sensor. The remaining 44 focusing points are horizontal-line sensitive (except with EF 70-200mm f/2.8L USM + Extender EF 1.4x).

28-80/2.8-4L, 300/4L, 300/4L IS, 500/4L IS, 600/4L, 600/4L IS, 70-200/4L

•With Extender EF 1.4x:

200/2.8L, 200/2.8L II, 300/2.8L, 300/2.8L IS, 400/2.8L, 400/2.8L II, 400/2.8L IS

•With Extender EF 2x: 135/2L, 200/1.8L

(3)With the following lenses, if the maximum aperture is anywhere from f/6.7 to f/8 when an Extender is attached, the center focusing point will be sensitive to

horizontal lines only. The other focusing points cannot be used for AF.

•With Extender EF 1.4x:

400/5.6L, 500/4.5L, 100-400/4.5-5.6L IS

•With Extender EF 2x:

300/4L, 300/4L IS, 500/4L IS, 600/4L, 600/4L IS, 70-200/4L

• When the < > button is pressed, the display shown on the right appears on the LCD panel

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