<P> Lens speed refers to the maximum aperture diameter , or minimum f - number , of a photographic lens . A lens with a larger maximum aperture ( that is , a smaller minimum f - number ) is called a `` fast lens '' because it can achieve the same exposure with a faster shutter speed . Conversely , a smaller maximum aperture ( larger minimum f - number ) is `` slow '' because it delivers less light intensity and requires a slower ( longer ) shutter speed . </P>
<P> Lens speed refers to the maximum aperture diameter , or minimum f - number , of a photographic lens . A lens with a larger maximum aperture ( that is , a smaller minimum f - number ) is called a `` fast lens '' because it can achieve the same exposure with a faster shutter speed . Conversely , a smaller maximum aperture ( larger minimum f - number ) is `` slow '' because it delivers less light intensity and requires a slower ( longer ) shutter speed . </P>
what does the speed of a lens mean
what does the speed of a lens mean
maximum aperture diameter , or minimum f - number , of a photographic lens . A lens with a larger maximum aperture ( that is , a smaller minimum f - number )
maximum aperture diameter , or minimum f - number , of a photographic lens . A lens with a larger maximum aperture ( that is , a smaller minimum f - number )