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In geometric optics, distortion is a deviation from rectilinear projection; a projection in which straight lines in a scene remain straight in an image.It is a form of optical aberration that may be distinguished from other aberrations such as spherical aberration, coma, chromatic aberration, field curvature, and astigmatism in a sense that these impact the image sharpness without changing an ...
PC Magazine reports 3.1% distortion at 8 mm and 0.7% at 12 mm. [8] It also reports that distortion switches to pincushion distortion of 1.4% at 16 mm. [8] SLAR Gear reports that the point of convergence between barrel and pincushion is about 13 mm. [3] Foreground subjects seem abnormally large compared to similar background subjects with this ...
Fig. 2b: An instrumental pincushion distortion of = leads to an almost complete elimination of the globe effect. The image of an afocal optical instrument is distortion-free if the f-tan theta condition, also known as tangent condition and first defined by Bow and Sutton in 1861, is satisfied: [4] = .
The reverse, in which the perimeter is magnified more than the center, is known as "pincushion distortion" (figure 3b). This effect is called lens distortion or image distortion, and there are algorithms to correct it. Systems free of distortion are called orthoscopic (orthos, right, skopein to look) or rectilinear (straight lines). Figure 4
In other words, it is a lens with little or no barrel or pincushion distortion. At particularly wide angles, however, the rectilinear perspective will cause objects to appear increasingly stretched and enlarged as they near the edge of the frame. These types of lenses are often used to create forced perspective effects.
Today the complex surfaces of a progressive lens can be cut and polished on computer-controlled machines, allowing 'freeform surfacing', as opposed to the earlier casting process, thus explaining the difference in price. In short, the price is based on the technology used and the year the lens came to market.
Highest listing price on eBay: $750 Hazel Atlas Blue Royal Lace stands out among Depression glass patterns, prized for its intricate design and vibrant cobalt blue hue. Produced between 1934 and ...
For example, a greater degree of barrel and pincushion distortion is tolerated in lenses that span the focal length range from wide angle to telephoto with a focal ratio of 10× or more than would be acceptable in a fixed focal length lens or a zoom lens with a lower ratio. Although modern design methods have been continually reducing this ...