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Esotropia is a form of strabismus in which one or both eyes turn inward. The condition can be constantly present, or occur intermittently, and can give the affected individual a "cross-eyed" appearance. [1] It is the opposite of exotropia and usually involves more severe axis deviation than esophoria. Esotropia is sometimes erroneously called ...
Prism (optics) An optical prism is a transparent optical element with flat, polished surfaces that are designed to refract light. At least one surface must be angled — elements with two parallel surfaces are not prisms. The most familiar type of optical prism is the triangular prism, which has a triangular base and rectangular sides.
Amblyopia. Anisometropia is a condition in which a person's eyes have substantially differing refractive power. [1] Generally, a difference in power of one diopter (1D) is the threshold for diagnosis of the condition . [2] [3] Patients may have up to 3D of anisometropia before the condition becomes clinically significant due to headache, eye ...
The history of the single-lens reflex camera (SLR) begins with the use of a reflex mirror in a camera obscura described in 1676, but it took a long time for the design to succeed for photographic cameras. The first patent was granted in 1861, and the first cameras were produced in 1884, but while elegantly simple in concept, they were very ...
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].
However, for the record: the first autofocus lens for a still camera was the Konishiroku Konica Hexanon 38mm f/2.8 built into the Konica C35 AF (1977, Japan) 35mm point-and-shoot; the first autofocus lens for an SLR camera was the unnamed 116mm f/8 built into the Polaroid SX-70 Sonar (1978, USA) instant film SLR; the first interchangeable ...
Subjective Refraction is a technique to determine the combination of lenses that will provide the best corrected visual acuity (BCVA). [1] It is a clinical examination used by orthoptists, optometrists and ophthalmologists to determine a patient's need for refractive correction, in the form of glasses or contact lenses.
The 35mm SLR camera Alpa-Reflex has its origins back in the 1930s when a Swiss precision mechanical manufacturer decided to diversify their product range, having mainly relied on manufacturing parts for the watch industry. They sought outside assistance and by 1939 the plans were ready and building cameras commenced at a very slow rate.
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