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The most common application for this is the treatment of strabismus. By moving the image in front of the deviated eye, double vision can be avoided and comfortable binocular vision can be achieved. Other applications include yoked prism where the image is shifted an equal amount in each eye.
It is also the principle used in corneal pachymetry, the mapping of corneal topography, done prior to refractive eye surgery such as LASIK, and used for early detection of keratoconus.
Aperture information was relayed through Nikon's "ADR" (Aperture Direct Readout) which was a window at the top center of the viewfinder that got its information from a micro-prism that read small numbers at the top of the mounted lens, of which type 'AI' (Aperture Indexing) or 'AIS' (Aperture Indexing Shutter Priority) lenses had printed behind ...
The Catadioptric system, where a spherical reflector is combined with a lens with the opposite spherical aberration, corrects the common optical errors of a reflector such as the Cassegrain system, making it suitable for devices that need a large aberration free focal plane (cameras).
Aberration can be defined as a departure of the performance of an optical system from the predictions of paraxial optics. [2] In an imaging system, it occurs when light from one point of an object does not converge into (or does not diverge from) a single point after transmission through the system.
The amount of aberration due to astigmatism is proportional to the square of the angle between the rays from the object and the optical axis of the system. With care, an optical system can be designed to reduce or eliminate astigmatism. Such systems are called anastigmats .
The optical quality of the eye is limited by optical aberrations, diffraction and scatter. [1] Correction of spherocylindrical refractive errors has been possible for nearly two centuries following Airy's development of methods to measure and correct ocular astigmatism.
The Petzval lens is one design which has significant field curvature; images taken with the lens are very sharp in the centre, but at greater angles the image is out of focus. Film cameras may be able to bend their image planes to compensate, particularly when the lens is fixed and known.
A roof pentamirror contains 3 mirrors. A pentamirror is an optical device used in the viewfinder systems of various single-lens reflex cameras instead of the pentaprism. It is used to reverse again the laterally reversed image coming from the reflex mirror. [1]
Tilt-lens photo of a model train. Note how the focus plane is along the train, and how the blurring of the background proceeds from left to right. Tilt–shift photography is the use of camera movements that change the orientation or position of the lens with respect to the film or image sensor on cameras .