T stops are a photographic measurement that provides a more accurate representation of the light actually passing through a lens than traditional f-numbers. While f-numbers indicate the ratio of the lens’s aperture diameter to its focal length, T stops account for the lens’s actual light transmission, including losses caused by the glass and coatings.
Using T stops allows photographers and cinematographers to achieve precise exposure control, especially when working with multiple lenses or in professional video production. By understanding and applying T stops, photographers can ensure consistent brightness and accurate exposure across different lenses and shooting conditions.