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A Fresnel lens (/ ˈ f r eɪ n ɛ l,-n əl / FRAY-nel, -nəl; / ˈ f r ɛ n ɛ l,-əl / FREN-el, -əl; or / f r eɪ ˈ n ɛ l / fray-NEL [1]) is a type of composite compact lens which reduces the amount of material required compared to a conventional lens by dividing the lens into a set of concentric annular sections.
Top view of Bessamatic Deluxe camera with Color-Skopar X lens. The leaf shutter is a Synchro-Compur unit mounted behind the interchangeable lens, which uses the DKL-mount, although lenses made for the Bessamatic are not generally compatible with other DKL-mount cameras, and the Bessamatic DKL-mount will not generally accept non-Voigtländer lenses without physical modifications. [1]
These lenses are generally used for plus (hyperopic) corrections at about 12 diopters or higher. A similar sort of eyeglass lens is the myodisc, sometimes termed a minus lenticular lens, used for very high negative corrections. More aesthetic aspheric lens designs are sometimes fitted. [3]
The effects of extended contact lens wear on the cornea have been studied extensively and are well-documented. When determining the effects of long-term contact lens use on the cornea, many studies do not differentiate between users of hard and soft contact lenses, while studies that have made this differentiation have found similar results.
The original Vitessa was introduced in 1950 with a fast Ultron 50 mm f /2.0 lens. [2] It was joined later by a version with a Color-Skopar 50 mm f /3.5 (Tessar-type) lens.. Contemporary marketing materials emphasized the rapid operation of the camera: by pressing the shutter release button, positioned on the top deck for the photographer's right index finger, the camera doors opened and the ...
Rolleiflex SL35 (black) with 50 mm f /1.8 Planar lens. The Rolleiflex SL35 was a line of 35mm SLR cameras which were developed and built by Rollei from the 1970s until the 1990s.
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