Lens Speed Lens speed, also known as lens aperture or lens brightness, refers to the maximum aperture diameter of a camera lens, expressed as a numerical f-stop value. A lens with a larger maximum aperture (smaller f-stop number) is considered "faster" because it allows more light to pass through the lens to the camera sensor, enabling faster shutter speeds and better performance in low-light conditions.
Fast lenses are desirable for situations where capturing fast-moving subjects, achieving shallow depth of field, or shooting in dimly lit environments is required. The speed of a lens is determined by its maximum aperture size relative to the focal length of the lens. For example, a lens with a maximum aperture of f/2.8 is considered faster than a lens with a maximum aperture of f/4.0. Fast lenses are commonly used in portrait photography, sports photography, and photojournalism, where the ability to capture sharp, well-exposed images in challenging lighting conditions is essential. |
