Zograscope
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A zograscope is an optical device for magnifying flat pictures that also has the property of enhancing the sense of the depth shown in the picture. It consists of a large
magnifying lens A magnifying glass is a convex lens that is used to produce a magnified image of an object. The lens is usually mounted in a frame with a handle. A magnifying glass can be used to focus light, such as to concentrate the sun's radiation to cre ...
through which the picture is viewed. Devices containing only the lens are sometimes referred to as graphoscopes. Other models have the lens mounted on a stand in front of an angled
mirror A mirror or looking glass is an object that Reflection (physics), reflects an image. Light that bounces off a mirror will show an image of whatever is in front of it, when focused through the lens of the eye or a camera. Mirrors reverse the ...
. This allows someone to sit at a table and to look through the lens at the picture flat on the table. Pictures viewed in this way need to be left-right reversed; this is obvious in the case of writing. A print made for this purpose, typically with extensive graphical projection perspective, is called a ''
vue d'optique ''Vue d'optique'' (French), ''vue perspective'' or perspective view refers to a genre of etching popular during the second half of the 18th century and into the 19th. ''Vues d'optique'' were specifically developed to provide the illusion of depth wh ...
'' or "perspective view". Zograscopes were popular during the later half of the 18th century as parlour entertainments. Most existing ones from that time are fine furniture, with turned stands, mouldings, brass fittings, and fine finishes. According to
Michael Quinion Michael Quinion (born c. 1943) is a British etymologist and writer. He ran World Wide Words, a website devoted to linguistics. He graduated from Peterhouse, Cambridge, where he studied physical sciences and after which he joined BBC radio as a ...
, the origin of the term is lost, but it is also known as a diagonal mirror, as an optical pillar machine, or as an optical diagonal machine. In Japan, the zograscope became known as 和蘭眼鏡 (Oranda megane, 'Dutch glasses') or 覗き眼鏡 (nozoki megane 'peeping glasses'), and the pictures were known as 眼鏡絵 ( megane-e, 'optique picture') 繰絵 (karakuri-e 'tricky picture').


History

*In 1570,
John Dee John Dee (13 July 1527 – 1608 or 1609) was an English mathematician, astronomer, astrologer, teacher, occultist, and alchemist. He was the court astronomer for, and advisor to, Elizabeth I, and spent much of his time on alchemy, divinatio ...
wrote ''A very fruitfull Preface ... specifying the chiefe Mathematicall Scieces, etc.'' in which he defined "zographie" as a mathematical art for representing visual images. *In 1677, German writer Johann Christoph Kohlhans described the effect of a convex lens in a
camera obscura A camera obscura (; ) is a darkened room with a aperture, small hole or lens at one side through which an image is 3D projection, projected onto a wall or table opposite the hole. ''Camera obscura'' can also refer to analogous constructions su ...
as if the subject appeared "naked before the eye in width, breadth, familiarity and distance".Blake, E. C. (2003). Zograscopes, virtual reality, and the mapping of polite society in eighteenth-century England. In L. Gitelman, & G. B. Pingree (Eds.), New Media, 1740-1915 (pp. 1-30). Cambridge, MA and London: MIT Press. Retrieved from https://mitpress-request.mit.edu/sites/default/files/titles/content/9780262572286_sch_0001.pdf *In 1692,
William Molyneux William Molyneux FRS (; 17 April 1656 – 11 October 1698) was an Irish writer on science, politics and natural philosophy. He is noted as a close friend of fellow philosopher John Locke, and for proposing Molyneux's Problem, a thought exper ...
wrote in his ''Dioptrica Nova'' how "Pieces of Perspective appear Natural and strong through Convex Glasses duly apply'd". *
Raree show A raree show, peep show or peep box is an exhibition of pictures or objects (or a combination of both), viewed through a small hole or magnifying glass. In 17th and 18th century Europe, it was a popular form of entertainment provided by wandering ...
boxes became very popular in the 17th century in The Netherlands. Some artists from the 17th-century
Dutch Golden Age painting Dutch Golden Age painting is the painting of the Dutch Golden Age, a period in Dutch history roughly spanning the 17th century, during and after the later part of the Eighty Years' War (1568–1648) for Dutch independence. The new Dutch Republ ...
, like
Pieter Janssens Elinga Pieter Janssens Elinga (1623–1682) was a Dutch Golden Age painter, mainly of domestic interior scenes with a strong emphasis on the rectangular geometrical elements of windows, floor tiling paintings, and other elements, and a few genre figure ...
and
Samuel Dirksz van Hoogstraten Samuel Dirksz van Hoogstraten (2 August 1627, in Dordrecht – 19 October 1678, in Dordrecht) was a Dutch painter of the Golden Age, who was also a poet and author on art theory. Biography Samuel Dirksz van Hoogstraten trained first with his fat ...
created a type of peep shows with an illusion of depth perception by manipulating the perspective of the view seen inside, usually the interior of a room. From around 1700 many of such "perspective boxes" or "optica" had a bi-convex lens with a large diameter and small dioptre for an exaggerated perspective, giving a stronger illusion of depth. Most pictures showed architectural and topographical subjects with linear perspectives. *In 1730, the first zograscopes, then called "optiques", were developed in Paris. Many perspective views, mainly of scenes from France and Germany but some from England, were published.Court, T. H., & von Rorh, M. (1935). On old instruments both for the accurate drawing and the correct viewing of perspectives. The Photographic Journal, 75(February), 54-66. Retrieved from https://archive.rps.org/archive/volume-75/734093?q=rohr%201935> Optiques incorporated a mirror but lacked any simple means of varying the distance of the lens from the image. *In 1745, the first English versions of the devices began to appear and soon many perspective views were printed for it, mostly of views with urban architecture. The oldest known reference to the English device is found in an advertisement in an English newspaper from April 1746. The term ''optical diagonal machine'' dates from as early as 1750.


Experience of zograscope viewing

Zograscopes created an unprecedentedly realistic experience of depicted scenes, so much so that Blake (2003) described it as "
virtual reality Virtual reality (VR) is a simulated experience that employs pose tracking and 3D near-eye displays to give the user an immersive feel of a virtual world. Applications of virtual reality include entertainment (particularly video games), educ ...
". A zograscope allowed viewers to move their eyes over very large scenes, yielding an immersive experience. Koenderink et al. (2013) showed that viewing photographs with a zograscope allowed observers to see depicted objects, such as
Rodin François Auguste René Rodin (12 November 184017 November 1917) was a French sculptor, generally considered the founder of modern sculpture. He was schooled traditionally and took a craftsman-like approach to his work. Rodin possessed a uniqu ...
's
Danaid (Rodin) ''Danaid'' is a sculpture by Auguste Rodin, based on the account in the ''Metamorphoses'' of Hypermnestra, eldest of the Danaïdes. It was originally conceived as part of his ''The Gates of Hell'' but was not included in the final version of th ...
, in objectively measured depth.


Explanation

Magnification Magnification is the process of enlarging the apparent size, not physical size, of something. This enlargement is quantified by a calculated number also called "magnification". When this number is less than one, it refers to a reduction in siz ...
of images was well understood by the time the first devices were constructed in the early 18th century. Basically, the image is placed at the focal point of a biconvex or plano-convex lens (a
magnifying glass A magnifying glass is a convex lens that is used to produce a magnified image of an object. The lens is usually mounted in a frame with a handle. A magnifying glass can be used to focus light, such as to concentrate the sun's radiation to crea ...
) allowing someone to view the magnified image at varying distances on the other side of the lens. Court and von Rorh (1935) suggested that the popularity of the early French models was because they allowed
presbyopic Presbyopia is physiological insufficiency of accommodation associated with the aging of the eye that results in progressively worsening ability to focus clearly on close objects. Also known as age-related farsightedness (or age-related long si ...
purchasers to see the images clearly despite the French fashion against wearing glasses. But Chaldecott (1953) doubted this could have been the sole reason for the devices' enduring popularity, leaving the major factor to be the realistic appearance of the depicted images. A zograscope makes a realistic experience for someone looking through it is by enhancing depth perception. One way is by minimizing other depth cues that specify the flatness and pictorial nature of the picture. The image is magnified, perhaps giving it a
visual angle Visual angle is the angle a viewed object subtends at the eye, usually stated in degrees of arc. It also is called the object's angular size. The diagram on the right shows an observer's eye looking at a frontal extent (the vertical arrow) tha ...
similar to the real scene the picture is depicting. The edges of the picture are blocked by the frame of the lens. The light coming from the lens to the eye is
collimated A collimated beam of light or other electromagnetic radiation has parallel rays, and therefore will spread minimally as it propagates. A perfectly collimated light beam, with no divergence, would not disperse with distance. However, diffraction p ...
, preventing accommodation. In early prints of interior scenes, some objects were hand-tinted with
saturated Saturation, saturated, unsaturation or unsaturated may refer to: Chemistry * Saturation, a property of organic compounds referring to carbon-carbon bonds ** Saturated and unsaturated compounds **Degree of unsaturation ** Saturated fat or fatty ac ...
colors whereas the background was tinted with "a pale wash" exploiting color contrast as a depth cue. A second way a zograscope could enhance depth perception is by creating binocular stereopsis. Because each eye views the image from a different position, the surface of the picture could have
binocular disparity Binocular disparity refers to the difference in image location of an object seen by the left and right human eye, eyes, resulting from the eyes’ horizontal separation (parallax). The brain uses binocular disparity to extract depth information from ...
from different magnification for the two eyes or from differences in the rotation of the images received by the eyes, so-called cyclodisparity. Such disparities create an overall slant of the picture surface around the vertical
meridian Meridian or a meridian line (from Latin ''meridies'' via Old French ''meridiane'', meaning “midday”) may refer to Science * Meridian (astronomy), imaginary circle in a plane perpendicular to the planes of the celestial equator and horizon * ...
or horizontal meridian respectively. As well, coloured parts of the image will be refracted differently for each eye, creating a version of
chromostereopsis Chromostereopsis is a visual illusion whereby the impression of depth is conveyed in two-dimensional color images, usually of red–blue or red–green colors, but can also be perceived with red–grey or blue–grey images. Such illusions ha ...
. Even if the binocular disparity were incorrect for the surface of the image or any coloured parts of it, the stereoscopic information tends to integrate with the other depth information in the image.


Construction of modern variation

A simple zograscope can be built from a frame (by cutting a rectangular opening in the bottom of a cardboard box) and placing in the frame a large, magnifying,
fresnel lens A Fresnel lens ( ; ; or ) is a type of composite compact lens developed by the French physicist Augustin-Jean Fresnel (1788–1827) for use in lighthouses. It has been called "the invention that saved a million ships." The design allows the c ...
available from stationery stores. When this is placed over a
computer monitor A computer monitor is an output device that displays information in pictorial or textual form. A discrete monitor comprises a visual display, support electronics, power supply, housing, electrical connectors, and external user controls. The di ...
displaying a photograph of a natural scene, the depicted depth will be enhanced.


See also

*
Peep show A peep show or peepshow is a presentation of a live sex show or pornographic film which is viewed through a viewing slot. Several historical media provided voyeuristic entertainment through hidden erotic imagery. Before the development of the ci ...
*
Stereoscope A stereoscope is a device for viewing a stereoscopic pair of separate images, depicting left-eye and right-eye views of the same scene, as a single three-dimensional image. A typical stereoscope provides each eye with a lens that makes the ima ...
*
Optical toys Optical toys form a group of devices with some entertainment value combined with a scientific, optical nature. Many of these were also known as "philosophical toys" when they were developed in the 19th century. People must have experimented with op ...
* Rayok


References


External links


Brightbytes.com




{{Authority control Audiovisual introductions in 1746 Magnifiers Optical toys