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The prism cover test (PCT) is an objective measurement and the gold standard in measuring strabismus, i.e. ocular misalignment, or a deviation of the eye. It is used by ophthalmologists and orthoptists in order to measure the vertical and horizontal deviation and includes both manifest and latent components. [1]
Prism lenses (here unusually thick) are used for pre-operative prism adaptation. Eye care professionals use prism correction as a component of some eyeglass prescriptions. A lens which includes some amount of prism correction will displace the viewed image horizontally, vertically, or a combination of both directions.
A corrective lens is a transmissive optical device that is worn on the eye to improve visual perception. The most common use is to treat refractive errors: myopia, hypermetropia, astigmatism, and presbyopia. Glasses or "spectacles" are worn on the face a short distance in front of the eye.
Chromatic aberration is used during a duochrome eye test to ensure that a correct lens power has been selected. The patient is confronted with red and green images and asked which is sharper.
A photographic loupe for examining film and prints. A loupe (/ ˈ l uː p / LOOP) is a simple, small magnification device used to see small details more closely. They generally have higher magnification than a magnifying glass, and are designed to be held or worn close to the eye.
Initially, the F3 model with the DE-2 eye-level finder was introduced, soon followed by the popular F3HP, or High Point camera, with the DE-3 High Eyepoint prism/finder. The major advantage of this finder was that the entire viewfinder image could be seen from a distance of 2.5 cm from the viewfinder.
In 2001, the Canon EF 400mm f/4 DO IS USM (Japan) was first diffractive optics lens for consumer cameras (for Canon EOS 35mm SLRs). Normally photographic cameras use refractive lenses (with the occasional reflective mirror) as their image forming optical system.
Flange focal distance. For an interchangeable lens camera, the flange focal distance ( FFD) (also known as the flange-to-film distance, flange focal depth, flange back distance ( FBD ), flange focal length ( FFL ), back focus [1] or register, depending on the usage and source) of a lens mount system is the distance from the mounting flange (the ...
The Prentice position is an orientation of a prism, used in optics, optometry and ophthalmology. In this position, named after the optician Charles F. Prentice, the prism is oriented such that light enters it at an angle of 90° to the first surface, so that the beam does not refract at that surface. All the deviation caused by the prism takes ...
The Canon FT QL is a 35mm single-lens reflex camera introduced by Canon Inc. in March 1966. It has a Canon FL lens mount compatible with the large range of FL series lenses. The FT can also operate the later Canon FD series lenses in stop-down mode, but the earlier R series has a different lens aperture mechanism and cannot be used, although ...