Technical Description; Eye Control - Canon EOS 7 Service Manual

1. TECHNICAL DESCRIPTION

1.1 E C
YE ONTROL
(1) Basic Configuration of Eye Control Optics
The basic configuration of the Eye Control optics is shown in Fig. 2-1. The infrared-
emitting diodes (IRED) are integrated in the eyepiece frame. They illuminate the
photographer's eye, and the light reflecting off the eye enters the camera to reach the
dichroic mirror. The dichroic mirror reflects the upper part of the light which enters
the image-formation lens. An image of the eye thereby forms on the Eye Control
BASIS.
The dichroic mirror has a special coating that enables 85 percent or higher
transmittance of visible light, a reflectance of 90 percent or higher of the Eye Control
IRED light (infrared: approx. 880 nm), and a 90 percent or higher transmittance of
SI-LED light (red: approx. 660 nm).
The IRED illumination optics (Fig. 2-2) consists of eight IREDs in the eyepiece frame,
like the EOS Elan II E/50 E/55. As shown in Table 2-1, each IRED has a specific
function in detecting the eye in the respective camera orientation (vertical or
horizontal). The camera orientation is detected by a small camera orientation
detection switch (Fig. 2-5) which is also used in the EOS Elan II E/50 E/55.
The basic operating principles of Eye Control are almost the same as with previous
Eye Control cameras.
Eyepiece lens 1
Eyepiece lens 2
Protective glass
Eye Control BASIS
Focusing screen
Pentaprism
LED-4
Dichroic mirror
Cross prism
Main mirror
Fig. 2-1 Eye Control Optics
2-1
Part 2: Technical Information
LED-5
LED-3
LED-1
LED-2
SI prism 1
LED-7
SI prism 1
LED-6