Viewfinder - Canon EOS 7 Service Manual

Part 2: Technical Information
1.3 V
IEWFINDER
The EOS ELAN 7 E / EOS 30 is the first EOS camera to have a viewfinder incorporating
three optical systems: Eye Control, dioptric correction, and SI display.
The viewfinder's basic optical system is similar to the EOS ELAN II E / EOS 50 E's
viewfinder. However, it also has dioptric correction optics. The viewfinder magnification
of 0.7x is also the same as the EOS ELAN II E / EOS 50 E's viewfinder, thanks to the
optical light path made short by the pentaprism's highly refractive glass.
(1) Configuration
As shown in Fig. 2-12, the viewfinder's basic optical system consists of a 45-deg.
partially-silvered mirror (60% reflectance and 40% transmittance), New Lasermatte
focusing screen (with fresnel lens), mask, pentaprism, dichroic mirror, concave
eyepiece lens (eyepiece lens 1), convex eyepiece lens (eyepiece lens 2), protective
glass, and other components.
(2) SI display optics
Like the EOS A2/A2E/5, the EOS ELAN 7 E / EOS 30 has SI-LEDs in front of the
pentaprism to illuminate the five horizontal focusing points. In addition, it has
SI-LEDs on the sides of the mirror box for illuminating the top and bottom focusing
points. Thus, it has two separate SI display optical systems. By making the SI optical
system for the top and bottom focusing points separate from the horizontal system,
the light flux is separate from the one for the five horizontal focusing points. The
result is excellent visibility.
The SI-LEDs used and the brightness are the same as with the EOS ELAN II E / EOS
50 E. Figure 2-13 shows the SI display optical system.
(3) Dioptric correction
The eyepiece lens consists of 2 elements in 2 groups. By using a different material for
element (plastic polycarbonate or acrylic) chromatic aberrations are effectively
corrected. Dioptric correction (–2.5 to +0.5) is enabled by moving eyepiece lens 2
(convex) forward or back.
2-8