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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 aim is to improve ...
Geometrical optics, or ray optics, is a model of optics that describes light propagation in terms of rays.The ray in geometrical optics is an abstraction useful for approximating the paths along which light propagates under certain circumstances.
Petzval's lens established two new features: firstly, it was faster compared to previous lenses, with a maximum aperture of 1:3.6. In comparison to Daguerre's daguerreotype camera lens of 1839, Petzval's design had 22 times the light-gathering capacity, which for the first time enabled portraits under favourable conditions with exposure times ...
AI lenses enabled lenses to be mounted without having to align the lens with the camera body's "rabbit ears". The F2AS Photomic (DP-12 head) was the most advanced F2 version and the chrome version with Nikkor AI 50 mm f/1.4 lens had a US list price of $1,278 in 1978.
All manual-focus lenses for Mamiya 645 are Sekor C lenses, which Mamiya used to designate multi-coated lenses. [ 1 ] E — only for the 70mm f/2.8 E lens sold as a kit with the original M645, apparently late in the M645's production run to differentiate it from the leaf-shutter version.
Efforts must first be made to identify and treat the underlying cause of the problem. Treatment options include eye exercises, [2] wearing an eye patch on alternative eyes, [2] [24] prism correction, [26] [24] [27] and in more extreme situations, surgery [5] [28] or botulinum toxin. [29]
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