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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]
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. [1] It is used by ophthalmologists and orthoptists in order to measure the vertical and horizontal deviation and includes both manifest and latent components. [1]
Corrective lens. 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.
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 ...
Using a positive lens of focal length f, a virtual image results when S 1 < f, the lens thus being used as a magnifying glass (rather than if S 1 ≫ f as for a camera). Using a negative lens ( f < 0 ) with a real object ( S 1 > 0 ) can only produce a virtual image ( S 2 < 0 ), according to the above formula.
Spherical aberration is the cause of night myopia and is commonly increased after myopic LASIK and surface ablation. It results in halos around point images. Spherical aberration exacerbates myopia in low light (night myopia). In brighter conditions, the pupil constricts, blocking the more peripheral rays and minimizing the effect of spherical ...
Gamma correction is a type of power law function whose exponent is the Greek letter gamma ( γ ). It should not be confused with the mathematical Gamma function. The lower case gamma, γ, is a parameter of the former; the upper case letter, Γ, is the name of (and symbol used for) the latter (as in Γ ( x )).
Correction, July 3: A news item below on Runway's debut of its Gen 3 Alpha text-to-video AI model has been corrected. An earlier version of the item said Gen 3 Alpha was available for free.