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Prism dioptres. Prism correction is commonly specified in prism dioptres, a unit of angular measurement that is loosely related to the dioptre. Prism dioptres are represented by the Greek symbol delta (Δ) in superscript. A prism of power 1 Δ would produce 1 unit of displacement for an object held 100 units from the prism. [2]
Lenticular lenses are sometimes used as corrective lenses for improving vision. A bifocal lens could be considered a simple example. Lenticular eyeglass lenses have been employed to correct extreme hyperopia (farsightedness), a condition often created by cataract surgery when lens implants are not possible.
The Photomic prism head later evolved to include the Photomic T with TTL in 1965, a behind-the-lens metering prism head which metered an averaging pattern of the focusing screen. The later center-area reading Photomic Tn, concentrated 60% of its sensitivity in the central portion of the focusing screen and the remaining 40% for the outlying ...
Twin-lens reflex camera. The front of a Kinaflex twin-lens reflex camera. The focus rings of the two lenses are coupled with gears around their circumference in this simple design. A twin-lens reflex camera ( TLR) is a type of camera with two objective lenses of the same focal length. One of the lenses is the photographic objective or "taking ...
Sodium vapor process aka "yellowscreen" method. The sodium vapor process (occasionally referred to as yellowscreen) is a photochemical film technique for combining actors and background footage. It originated in the British film industry in the late 1950s and was used extensively by Walt Disney Productions in the 1960s and 1970s as an ...
A reflex finder is a viewfinder system with a mirror placed behind a lens. The light passing through the lens is reflected by the mirror to a focusing screen, usually ground glass. The image formed on this ground glass can be observed directly, giving a waist-level reflex finder, or through a redressing optical device (set of mirrors or prism ...
Contact lenses. to correct refractive errors of the eye; a little invasive. Phoropter. used in refraction testing. Tonometers. used to determine the intraoccular pressure (IOP) - useful in glaucoma; video link for various types of tonometers. Speculum: to keep the eyes open during any operation. Universal eye speculum.
June 12, 2024 at 10:58 AM. While most people rarely go anywhere without their cell phones in hand, the royals are likely held to a different standard when it comes to touting around mobile devices ...