The type of shutter that works by passing a pair of curtains across in front of the film is called a _____ shutter.

• A. Electronic shutter
• B. Rolling shutter
• C. Focal plane
• D. Leaf shutter

Answer: (C)

This question tests understanding of shutter mechanisms, specifically a shutter that sits at the film plane and uses two curtains to control exposure. When the first curtain starts to move, it clears a portion of the film, and the second curtain follows to stop the exposure. The time between the start of the first curtain and the completion of the second defines the shutter speed. At slower speeds, the curtains can expose the entire frame, while at faster speeds a narrow slit travels across the frame, yielding very short exposures. This setup is called a focal-plane shutter because it operates at the plane where the film lies, right in front of the film itself. It’s different from a leaf shutter, which is built into the lens and uses blade-based openings, from a rolling shutter, which describes how sensor rows are read rather than a physical curtain, and from an electronic shutter, which has no mechanical curtains.