pincushion distortion

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pincushion distortion

irregular image produced when axial magnification is greater than peripheral magnification. See: Petzval surface.

pin·cush·i·on dis·tor·tion

(pin'kush-ŭn dis-tōr'shŭn)
Irregular image produced when axial magnification is greater than peripheral magnification.
See: Petzval surface

distortion

Aberration of an optical system resulting in an image which does not conform to the shape of the object, somewhat resembling the image viewed through a cylindrical lens. This is due to an unequal magnification of the image. Distortion can be barrel-shaped (barrel-shaped distortion) in which the corners of the image of a square are closer to the centre than the middle part of the sides; or pincushion (pincushion distortion) in which the corners of the image of a square are farther from the centre than the middle part of the sides (Fig. D10). Example of barrel-shaped distortion: a square object seen through an uncorrected negative spectacle lens. Example of pincushion distortion: a square object seen through an uncorrected positive spectacle lens. See correction; fisheye lens; sine condition.
Fig. D10 Distortion (O, object; A, pincushion distortion; B, barrel-shaped distortion)enlarge picture
Fig. D10 Distortion (O, object; A, pincushion distortion; B, barrel-shaped distortion)
References in periodicals archive ?
More whimsical silver pincushions modelled as miniature domesticated, farmyard and wild animals flowed out of the city to delight Victorian and Edwardian ladies who collected them as fervently as they are sought after today.
This exceptionally beautiful eight-lobed pincushion was distinctive in exhibiting virtuosity in two very different decorative techniques: finely worked floral moosehair embroidery within delicate borders of raised beadwork and on a red woolen background.
Pincushion describes a purple, pink, sometimes cream flower with petals that seem to hold up a cushion stuck with pins.
It will also harbor some of last remaining populations of the threatened Siler pincushion cactus (Pediocactus sileri) and the endangered dwarf bear poppy (Arctomecon humilis), a plant found only in Washington County, Utah.
To make this point-tool pincushion, just glue the foam to 1/2-in.
Witness the picture above, kindly sent tome by regular column contributors Nick and Cherry Bowmaker, of a robin's pincushion, which they discovered beside the Macclesfield Canal recently.
The 19-millimeter EF ($89.95) sports an impressive 65[degrees] field of view that is free of pincushion distortion and field curvature out to the edges, and a comfortable 19 mm of eye relief.
I still occasionally encounter a nurse with great marksmanship, but I've also had experiences when I've come out of a lab or examination room feeling like a pincushion.
Why is this guy trying to pass as a human pincushion? To secure a spot in the Guinness World Records 2003, Garry Turner of Lincolnshire, England, clipped 153 clothespins to his face.
There are musclemen showing their self-sufficiency, and the Human Pincushion, Ronald C.
Examining the Nikon we noted no astigmatism, curvature of field, rolling distortion, or pincushion distortion.
Just south of the camp lie the remains of the 7525-acre Hondo Fire; after six years the front of the mountain is still a pincushion of burnt trees.