What shutter term describes the mechanism that uses two curtains moving across the film plane?

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

Answer: (C)

Two-curtain movement across the film plane is called a focal-plane shutter. This mechanism sits in the camera body and exposes the film by letting a narrow slit of light travel across the frame as the curtains move. The time it takes for that slit to cross the film determines the exposure duration, which is why you can get very fast shutter speeds that freeze motion or slower speeds that blur motion. This differs from a leaf shutter, which is built into the lens and opens a full rectangular area at once, and from an electronic shutter, which uses sensor readout with no moving curtains.