Canon SPEEDLITE 540EZ Service Manual page 23

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Part 2: Technical Information

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1.1 AF Auxiliary Light Function

1) Configuration

Two high-brightness light-emitting diodes (one for the center focusing point and

one for the left and right side focusing points) with a peak wavelength of 695 nm

are used for the AF auxiliary light source. The auxiliary light is emitted in the

pattern shown in Figure 2-2 according to commands from the camera, and covers

all five focusing points for lenses with focal lengths of 24mm or longer. The

effective range is approx. 0.5~15 m for the center point, and approx. 0.7~6 m for

the side points.

The optical system is configured as illustrated in Figure 2-1, with the optical axis

of the AF auxiliary light slanted slightly downward at an angle of 2° relative to the

optical axis of the shooting lens (providing a cross-over point with the EOS-1N's

optical axis approximately three meters from the camera). Also, part of the AF

auxiliary light for the center focusing point is directed downward by a prism plate

at an angle of 5.75° (crossing the EOS-1N's optical axis approximately 83 cm from

the camera), simultaneously providing AF auxiliary light at the center point for

both normal and close-up shooting.

Auxiliary light pattern mask

for center focusing point

Auxiliary light pattern mask

for side focusing points

AF auxiliary light lens

Cylindrical lens

Prism plate

* Integrated with AF auxiliary light window panel

Figure 2-1 AF Auxiliary Light Optical System

¢ When using 24mm lens

¢ When using 105mm lens

Figure 2-2 Viewfinder Field of View and AF Auxiliary Light Pattern

2-1

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