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Tutorial

F-Stop Explained

By Marcus ReidUpdated September 12, 2026

[Demo data — development only. Specifications are illustrative; editorial copy is sample content.]

An f-stop is the ratio of the lens focal length to the aperture opening. Because it's a ratio, smaller numbers mean larger openings — f/1.8 is wide, f/16 is narrow.

Each full stop (f/1.4 → f/2 → f/2.8) halves the light.

M

Written by

Marcus Reid

Staff Writer

Marcus writes about technique, education and the business of photography.

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