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How does a leaf shutter work inside a camera lens?

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Diagram showing the negative-positive photographic process: a scene is captured on film in a camera, developed into a negative, projected onto paper with an enlarger, and developed again to produce a positive print. — technology of photography Figure 1: Sequence of negative–positive process, from the photographing of the original scene to enlarged print (see text).

A leaf shutter, also known as a diaphragm shutter, is a mechanism composed of several overlapping metal blades positioned inside or immediately behind the camera lens.12

When a photograph is taken, the shutter functions by swinging these blades simultaneously outward, which uncovers the lens opening to admit light to the image sensor or film. The blades remain in this open position for a predetermined duration, known as the exposure time, before closing again to block the light.12

The movement of these blades is typically powered by a combination of springs and electromagnets. The duration for which the shutter remains open is regulated by either an electronic circuit—often integrated with a light-metering system—or an adjustable mechanical escapement. While exposure times vary, they generally range between one second and 1/500 of a second. This design differs from the focal-plane shutter, which operates by moving a slit across the image plane rather than opening and closing at the lens position.12