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A pinhole occluder is an opaque disk with one or more small holes through it, used by ophthalmologists, orthoptists and optometrists to test visual acuity. The occluder is a simple way to focus light, as in a pinhole camera, temporarily removing the effects of refractive errors such as myopia. Because light passes only through the center of the ...
Early pinhole camera. Light enters a dark box through a small hole and creates an inverted image on the wall opposite the hole. [8]The first known description of pinhole photography is found in the 1856 book The Stereoscope by Scottish inventor David Brewster, including the description of the idea as "a camera without lenses, and with only a pin-hole".
Impossible object: Irradiation illusion: Isometric illusion: An isometric illusion (also called an ambiguous figure or inside/outside illusion) is a type of optical illusion, specifically one due to multistable perception. Jastrow illusion: The Jastrow illusion is an optical illusion discovered by the American psychologist Joseph Jastrow in 1889.
In addition to the gestalt principles of perception, water-color illusions contribute to the formation of optical illusions. Water-color illusions consist of object-hole effects and coloration. Object-hole effects occur when boundaries are prominent where there is a figure and background with a hole that is 3D volumetric in appearance.
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Slide – a tube used to get an object to an otherwise impossible to reach location. Slip – to retain the top or bottom cards, or both, during an overhand shuffle. Slip-on corner – a corner of a card that can be placed over the actual corner of a card. These corners show a rank and suit different from the card's actual.
A camera obscura consists of a box, tent, or room with a small hole in one side or the top. Light from an external scene passes through the hole and strikes a surface inside, where the scene is reproduced, inverted (upside-down) and reversed (left to right), but with color and perspective preserved. [10]
The stick not in the trapeze is inserted between the strings on either side of the stick in the trapeze. The diabolo is tossed into the air, and the strings form an X. The diabolo is caught on the X, and then it can be tossed and caught again. Suicide/stick release: Any trick in which the performer releases one stick, and catches it again.