Maximum and minimum apertures Aperture

the specifications given lens typically include maximum , minimum aperture sizes, example, f/1.4–f/22. in case, f/1.4 maximum aperture (the widest opening), , f/22 minimum aperture (the smallest opening). maximum aperture opening tends of interest , included when describing lens. value known lens speed , affects exposure time. aperture proportional square root of light admitted, , inversely proportional square root of required exposure time, such aperture of f/2 allows exposure times 1 quarter of f/4.

the aperture range of 50mm minolta lens, f/1.4–f/16

lenses apertures opening f/2.8 or wider referred fast lenses, although specific point has changed on time (for example, in 20th century aperture openings wider f/6 considered fast). fastest lenses common 35 mm film format in general production have apertures of f/1.2 or f/1.4, more @ f/1.8 , f/2.0, , many @ f/2.8 or slower; f/1.0 unusual, though sees use. when comparing fast lenses, image format used must considered. lenses designed small format such half frame or aps-c need project smaller image circle lens used large format photography. optical elements built lens can far smaller , cheaper.

in exceptional circumstances lenses can have wider apertures f-numbers smaller 1.0; see lens speed: fast lenses detailed list. instance, both current leica noctilux-m 50mm asph , 1960s-era canon 50mm rangefinder lens have maximum aperture of f/0.95. cheaper alternatives have appeared in recent years, such cosina voigtländer 17.5mm f/0.95, 25mm f/0.95 , 42.5mm f/0.95 manual focus lenses micro 4 thirds system.

professional lenses movie cameras have f-numbers small f/0.75. stanley kubrick s film barry lyndon has scenes shot candlelight nasa/zeiss 50mm f/0.7, fastest lens in film history. beyond expense, these lenses have limited application due correspondingly shallower depth of field – scene must either shallow, shot distance, or defocused, though may desired effect.

zoom lenses typically have maximum relative aperture (minimum f-number) of f/2.8 f/6.3 through range. high-end lenses have constant aperture, such f/2.8 or f/4, means relative aperture stay same throughout zoom range. more typical consumer zoom have variable maximum relative aperture since harder , more expensive keep maximum relative aperture proportional focal length @ long focal lengths; f/3.5 f/5.6 example of common variable aperture range in consumer zoom lens.

by contrast, minimum aperture not depend on focal length – limited how narrowly aperture closes, not lens design – , instead chosen based on practicality: small apertures have lower sharpness due diffraction, while added depth of field not useful, , there little benefit in using such apertures. accordingly, dslr lens typically have minimum aperture of f/16, f/22, or f/32, while large format may go down f/64, reflected in name of group f/64. depth of field significant concern in macro photography, however, , there 1 sees smaller apertures. example, canon mp-e 65mm can have effective aperture (due magnification) small f/96. pinhole optic lensbaby creative lenses has aperture of f/177.