lenses While the fastest lenses in general production in the 2010s were 1.2 or 1.4, the 2020s have seen several 0.95 lenses, see below. What is considered "fast" has evolved to lower f-numbers over the years, due to advances in lens design, optical manufacturing, quality of glass, optical coatings, and the move toward smaller imaging formats. For example, the 1911 Encyclopædia Britannica states that "...[Lenses] are also sometimes classified according to their rapidity, as expressed by their effective apertures, into extra rapid, with apertures larger than 6; rapid, with apertures from 6 to 8; slow, with apertures less than 11" whilst today, 6 would be deemed at the rather slow end. For scale, note that 0.5, 0.7, 1.0, 1.4, and 2.0 are each 1 f-stop apart (2× as fast), as an f-stop corresponds to a factor of the square root of 2, about 1.4. Thus around 1.0, a change of 0.1 corresponds to about 1/4 of an f-stop (by linear approximation): 1.0 is about 50% faster than 1.2, which is about 50% faster than 1.4. , Canon, Nikon, Pentax and Sony all make an autofocus 50mm 1.4 lens. These are not unusual lenses and are relatively inexpensive. As of 2022, Canon also makes autofocus 50mm and 85mm 1.2 lenses, while Nikon makes a manual focus 58mm 0.95 lens and an autofocus 85mm 1.4; see Canon EF 50mm lenses and Canon EF 85mm lenses for details. Pentax makes a 50mm 1.4 lens and 55mm 1.4 lens for APS-C cameras; see Pentax lenses. Sony makes several 50mm 1.4 lenses as well as a 50mm 1.2. The maximum exposure time for hand-held photography can be increased with an image stabilisation system. In 2014, Panasonic introduced the fastest lens with in-built stabilisation, the Leica Nocticron 42.5 mm f/1.2, which can even be operated with dual image stabilisation (Dual I.S.), provided that the camera body has an additional stabilising system at the image sensor. In the mid 1960s, there was something of a fad for fast lenses among the major manufacturers. In 1966, in response to the trend, Carl Zeiss displayed a prop lens christened the Super-Q-Gigantar 40mm 0.33 at photokina. Made from various parts found around the factory (the lenses came from a darkroom condenser enlarger), the claimed speed and focal lengths were purely nominal and it wasn't usable for photography. Maximum possible speed Theoretically, the smallest f-number is 0 (or numerical aperture of