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Once only available in a rigid, gas-permeable form, toric lenses are now also available as soft lenses. In older people, astigmatism can also be corrected during cataract surgery. This can either be done by inserting a toric intraocular lens or by performing special incisions (limbal relaxing incisions). Toric intraocular lenses probably ...
The majority of autorefractors calculate the vision correction a patient needs (refraction) by using sensors that detect the reflections from a cone of infrared light. These reflections are used to determine the size and shape of a ring in the retina which is located in the posterior part of the eye.
Internal focusing, which focuses binoculars by moving internal mounted optical lenses located between the objective lens group and the prism assembly – or rarely located between the prism assembly and eyepiece lens assembly – within the housing without changing the volume of the binoculars. The addition of a focusing lens reduces the light ...
A ball lens is an optical lens in the shape of a sphere. Formally, it is a bi-convex spherical lens with the same radius of curvature on both sides, and diameter equal to twice the radius of curvature. The same optical laws may be applied to analyze its imaging characteristics as for other lenses. As a lens, a transparent sphere of any material ...
Optical aberration. 1: Imaging by a lens with chromatic aberration. 2: A lens with less chromatic aberration. In optics, aberration is a property of optical systems, such as lenses, that causes light to be spread out over some region of space rather than focused to a point. [1]
The B4 mount defines the sensor to have a diagonal size of 11 mm (a so-called 2/3" size sensor). The B4-mount is used by practically all 2/3" broadcast lenses and cameras (as of 2019). Although the standard was set in 1992, the B4 mount already existed before 1980. The Sony BVP-300, produced from 1978, was possibly the first camera with a B4 mount.
Petzval portrait lens. The Petzval objective, or Petzval lens, is the first photographic portrait objective lens (with a 160 mm focal length) in the history of photography. [1] It was developed by the Slovak mathematics professor Joseph Petzval in 1840 in Vienna, [2] with technical advice provided by Peter Wilhelm Friedrich von Voigtländer [ de].
Cyclotropia is a form of strabismus in which, compared to the correct positioning of the eyes, there is a torsion of one eye (or both) about the eye's visual axis. Consequently, the visual fields of the two eyes appear tilted relative to each other. The corresponding latent condition – a condition in which torsion occurs only in the absence ...