Zograscope

Rod Bantjes Collection, #RB-01

English(?) late 18^th century

Dimensions: H=59 cm, W=24 cm, D=31.3 cm (with mirror open)

Lens: ⌀=12 cm, ƒ=152 cm

 

Figure RB-01.1 –Zograscope
Photo © Rod Bantjes, 2025.

Figure RB-01.2 –View through the zograscope
This is a stereo image that you can free-view cross-eyed to get a feeling for the 3D effect. The image is a vue d'optique from the late 18th century. Photo © Rod Bantjes, 2025.

This is a biconvex-lens viewer for enhancing the 3D-effect of copper-plate engravings known as vues d'optique.

 

It is an example of an "optical machine." Zograscopes are distinguished from other diagonal-mirror viewers in the Optical Machine Taxonomy by the fact that they have no enclosing box or image-holder and so rely on a surface such as a table to support the image.

 

To appreciate the 3D effect you must look through the lens with both eyes at the image of a print reflected in the mirror (see Figure RB-01.2). You position the print upside-down at the base of the zograscope. Since the mirror reverses the print left-to right, vues d'optique often had titles printed in reverse so that they could be read when seen through the device.

 

This zograscope has a thumbscrew near the top of the column for adjusting the height of the lens-mirror assembly, so that the user can find the position that gives them the best 3D effect. Eighteenth-century writers recommend that distance between the print should and the lens should be approximately the focal length of the lens. That distance would make the direction of the two eyes parallel when looking at the surface of the print, just as they would be when looking at a distant horizon. This is supposed to make depicted landscapes appear to be at a great distance, and the illusion of a great space to open up before the viewer.

The 3D Effect

The zograscope is one of the most common forms of the "optical machine" – any viewer that uses a convex lens or concave mirror to enhance the 3D effect of an image. There are close to a hundred different varieties of optical machines, but the optical principles are the same for all of them, and you can follow this link to learn more about how it works .

 

The focal length of this lens is unusually long (152 cm), close to 3 times the distance to the image. While it does not conform to 18^th-century theory, it still produces a weak spatial effect.

Masking /Immersion

One of the explanations that people sometimes give for the supposedly "immersive" spatial effect is that the device masks out all visual distractions so that the eyes take in only the image and the mind can be absorbed into its imagined space. That explanation clearly does not apply to the zograscope as you can see from Figure RB-01.2.

 

If you move further back from the lens so that the edges of the print are not visible (about 18cm) then the image occupies only a small portion of your visual field. You see the zograscope mechanism all the way down to its base and far more of the room beyond than of the vue d'optique world in which you are supposed to be immersed.

Figure RB-01.3 – Zograscope, 1871
Source: Casella, C. F. 1871. An Illustrated and Descriptive Catalogue of Philosophical, Meteorological, Mathematical, Surveying, Optical and Photographic Instruments. London: P. Lane..

Figure RB-01.4 – Zograscope and Cubism
Source: Roger de la Fresnaye, 1913, Still Life [with Zograscope], 92.5 x 73.5 cm, Oil on canvas, Statens Museum for Kunst, Copenhagen.

Exposed Mechanism /Rational Recreation

The zograscope was popular in bourgeois households where curiosity and self-discovery of scientific principles were encouraged as part of children's' education. "Philosophical toys" like the optical machine were meant to part of this education and to instruct, but also to amuse and delight. It was important that children both enjoyed the illusion that the device created, but perhaps more important that they thought about how the illusion worked.

 

The open structure, that brings into view the machine's lenses and mirrors, was better suited to this sort of "rational recreation." The zograscope was perhaps not intended to be immersive, but rather to always encourage a critical remove on the part of the user.

 

Material evidence for this claim is the reverse printing of the descriptive information about each vue d'optique. That design choice assumes that people will be reading while looking into the machine in a way that invites rational rather than immersive engagement.

Long History of the Zograscope

The zograscope was not only one of the most popular of the optical machines, but also, in the form that you see it here (Figure RB-01.3), one of the most long-lived – from the mid-18^th century until at least 1871.

 

C. S. Casella was still selling them in 1871 when so many more 3D visual amusements were then available. His offering shares with my zograscope (Figure RB-01.1) many of the classic design features. It has a turned base and stand with a central column-like element. At the top of the column is a spool-like form with a wooden thumbscrew that secures the lens-mirror assembly and allows it to be adjusted up or down. The lens-case and mirror are rectangular and the frame that holds the lens-mirror assembly is turned with end-blocks joined by column-like forms. The verticals are topped by finials.

 

This enduring standard of design makes individual zograscopes difficult to date with accuracy.

 

The cubist painter, Roger de la Fresnaye, included a zograscope in a still-life that he painted in 1913 (Figure RB-01.4). Apparently it still could be found in some households in the early 20^th century. The cubists were interested in the constructed character of our spatial perception. I like to think that de la Fresnaye saw in the zograscope, as I do, a device that helped to lay bare the mechanisms by which our visual faculty constructs space.^[xxx]

 

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