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An extended hemispherical lens is a special type of plano-convex lens, in which the lens's curved surface is a full hemisphere and the lens is much thicker than the radius of curvature. Another extreme case of a thick convex lens is a ball lens, whose shape is completely round. When used in novelty photography it is often called a "lensball".
The most common type of long-focus lens is the telephoto lens, a design that uses special optical configurations to make the lens shorter than its focal length. A side effect of using lenses of different focal lengths is the different distances from which a subject can be framed, resulting in a different perspective .
This is any lens with a focal length longer than the diagonal measure of the film or sensor. [121] The most common type of long focus lens is the telephoto lens, a design that uses a special telephoto group to be physically shorter than its focal length. [122] Modern zoom lenses may have some or all of these attributes.
The focal length of an optical system is a measure of how strongly the system converges or diverges light; it is the inverse of the system's optical power. A positive focal length indicates that a system converges light, while a negative focal length indicates that the system diverges light. A system with a shorter focal length bends the rays ...
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.
Aperture. In biology, the pupil (appearing as a black hole) of the eye is its aperture and the iris is its diaphragm. In humans, the pupil can constrict to as small as 2 mm ( f/ 8.3) and dilate to larger than 8 mm ( f/ 2.1) in some individuals. In optics, the aperture of an optical system (including a system consisted of a single lens) is a ...
A zoom lens is a system of camera lens elements for which the focal length (and thus angle of view) can be varied, as opposed to a fixed-focal-length (FFL) lens ( prime lens ). A true zoom lens or optical zoom lens is a type of parfocal lens, one that maintains focus when its focal length changes. [1] Most consumer zoom lenses do not maintain ...
In optics, a thin lens is a lens with a thickness (distance along the optical axis between the two surfaces of the lens) that is negligible compared to the radii of curvature of the lens surfaces. Lenses whose thickness is not negligible are sometimes called thick lenses . The thin lens approximation ignores optical effects due to the thickness ...