Maximum Aperture

Maximum aperture is the widest opening available on a lens, expressed as an f-number. An f-number is the ratio of the lens focal length to the diameter of the aperture opening. A lower f-number means a larger opening and more light transmission. A lens with a maximum aperture of f/1.4 opens wider than one at f/5.6, admitting significantly more light and enabling faster shutter speeds in the same lighting conditions. Maximum aperture is one of the most important lens specifications for low-light performance and depth-of-field control.

Each full stop of aperture (f/1.0, f/1.4, f/2, f/2.8, f/4, f/5.6, f/8) represents a doubling or halving of light. Moving from f/2.8 to f/1.4 doubles the aperture diameter, quadruples the aperture area, and by the standard scale admits twice as much light, making f/1.4 two stops faster than f/2.8. In practical terms, two stops of difference means a shutter speed four times faster at f/1.4 than at f/2.8 for equivalent exposure. Fast lenses enable shooting in lower light without raising ISO or slowing the shutter.

Zoom lenses often have a variable maximum aperture that changes with the focal length. A lens marked f/3.5-5.6 has a maximum aperture of f/3.5 at the wide end and f/5.6 at the telephoto end. Constant aperture zooms such as f/2.8 maintain the same maximum aperture across the full zoom range. Constant aperture zooms are larger, heavier, and more expensive than variable aperture designs but provide consistent exposure when zooming without adjusting other settings.

In the M43 lens ecosystem, maximum apertures range from f/0.95 on Voigtlander Nokton manual focus primes to f/6.3 on budget telephoto zoom lenses. The OM System M.Zuiko Digital f/1.2 Pro series and the Panasonic Leica DG Nocticron 42.5mm f/1.2 represent the widest apertures available in autofocus M43 primes. Third-party options from 7Artisans, TTArtisan, and Meike extend the fast prime range at lower price points without autofocus.