Camera Craftsman - Photo Circuits

This issue of Camera Craftsman focuses on servo exposure-control systems, a fundamental topic for camera repair technicians. Written by Larry Lyells, the primary article offers a detailed introduction to photographic electronic circuits, specifically designed for technicians seeking deeper knowledge in photographic electronics.

The guide covers the basics of servo mechanisms found in cameras with small lens apertures, including movie cameras and cartridge-load cameras. The author explains how these sophisticated systems function and differ from conventional galvanometer-based systems. You'll discover the distinct advantages of servo motors: superior ruggedness compared to delicate instruments, lightning-fast response time, and automatic f-stop control capability.

The document details the complete servo exposure mechanism, including the sequence of operations the system must perform to determine correct aperture settings. Schematics and diagrams illustrate the error detector, controller, and drive motor operation. A comprehensive section covers the servo motor itself, its multiple coils, and how they interact to precisely control diaphragm opening.

The Kodak XL 320 serves as a concrete example with detailed schematic diagrams and troubleshooting procedures. Photographs of the housing and internal components aid practical understanding of servo exposure-control systems, making this issue invaluable for anyone working with automation-equipped cameras.