How to use a camera lucida

The camera lucida is generally considered to have been invented by the English chemist W. H. Wollaston in 1806-07, although there is some speculation that it is a reinvention of a device described by Kepler some 200 years earlier. The term camera lucida means 'light room' and it indicates that the device didn't require the darkened space that had been necessary for the earlier camera obscura. There is no projected image and it is based on very different optical principles. A camera lucida consists of a simple prism and lens that allow an artist to see the scene that they depicting superimposed over the paper that they are drawing on, so that they can simply trace around the image. The rest of the device comprises of a clamp and extendable arm, with which it can be securely fixed in position to one side of the artist's drawing board or sketch pad with the prism set at a convenient height.




A French camera lucida or 'Chambre Claire Universelle', made by Breveté S.G.D.G., with a set of 12 numbered lenses.

Detail of the prism (set within the black holder) and lens.

Looking downwards through the very edge of the prism, the subject is seen the correct way up on the drawing surface, as shown in the above photos.

As the superimposed images tend to be quite faint, white paper can be too bright for the image to appear clearly. Drawing in chalk on black paper can be used to achieve better results.

These instructions for the 'Chambre Claire Universelle' explain which of the different numbered lenses is to be used in various circumstances, dependant on the height of the prism above the paper and the distance of the subject being drawn. Increasing the height of the prism above the drawing surface creates a larger image.

A 19th century engraving by C. Varley made using a camera lucida, depicting G. Dollond who is also drawing with the device. George Dollond (1774-1852), who was a noted maker of telescopes and other optical instruments, helped popularise the camera lucida in England.

It was after using a camera lucida in 1833 that the the pioneer of photography William Fox Talbot began his attempts to fix images chemically.

David Hockney has speculated on how great artists have used the camera lucida in his book 'Secret Knowledge: Rediscovering the Lost Techniques of the Old Masters'. (for a very brief summary of some of these ideas, see his article in RA Magazine from Summer 1999).

A two-part BBC documentary based on Hockney's book is available on YouTube (Pt1, Pt2).


Further information on how to use a camera lucida can be found at Gilai Collectibles.


For an updated take of the same principle, an iPhone and iPad app called Camera Lucida is available which allows photographs taken with the camera to be traced onto paper, as demonstrated here.


(all photos © copyright Russell Light)

How to construct an Ames room

The Ames room was developed by Adelbert Ames Jr as part of his research into optics and perception during the 1930s and 40s. After an early career as a painter, Ames began to explore the relationship between visual art and the scientific study of vision. He studied opthalmology at Clark University, Massachusetts and became a professor of physiological optics, developing an interest optical illusions. As part of his research, he conducted a series of experiments that he called 'the distorted room demonstrations'.

When viewed from the correct position, an Ames room gives the illusion of a standard orthogonal room. It is actually a trapezoid shaped space, which means that people standing in different corners at the back of the room and who appear to be the same distance from the viewer, look as if they are completely different sizes. The optical illusion is so convincing that someone walking across the back of the room appears to increase or decrease in scale as they move from one side to the other.

An Ames room is constructed by plotting the visual rays from the chosen view point to the various points of the notional orthogonal room. Points in the Ames room can then be established on the same visual rays, either closer or further from the view point. The following example is quite a simple version of an Ames Room, where the floor and ceiling slope, but with walls that are still vertical. The dimensions of the wall on the right hand side have been reduced by exactly 50% compared to the left. The illusion can be developed further with sloping wall surfaces, whilst still maintaining the apparent appearance of an orthogonal space.

Plans, showing an orthogonal room on the left and the plan of an equivalent Ames room on the right (viewing position at bottom)

3D view showing the perceived orthogonal space

3D view showing the irregular space of the Ames room

Section through the Ames room showing visual rays

(images © copyright Russell Light)

A SketchUp model can be downloaded from the Google 3D Warehouse.


The principle of the Ames room is often used to create spatial illusions in films. Most recently, the effect has been used in the Lord of the Rings trilogy so that the hobbits would appear smaller than other taller characters.

Ames' original room also incorporated an anti-gravity illusion, that took advantage of the apparently flat floor that actually sloped. A ball would be appear to roll upwards along a grooved track that was positioned across the room.


Sources:

F Dubery & J Willats (1983) - 'Perspective and Other Drawing Systems', Herbert Press, London. Amazon link

R Gregory (1994) - 'Even Odder Perceptions', Routledge, Amazon link

3D model of perspective construction

I have added a 3D SketchUp model of the perspective construction used in the 'How to...' section.  This is not in order to demonstrate an alternative method of setting up a perspective drawing, but to help explain more clearly the geometry that underlies any perspective view, whether constructed in the traditional way or via a 3D CAD model.

(images © copyright Russell Light)

Clearly, a CAD model has many advantages in that it can be used as a basis for a whole series of drawings and different perspective views. However, it is still useful to develop an understanding of the basic principles of perspective by constructing a drawing manually, as this can help with composition and selecting a view, as well as being useful for sketches in the field or when a computer isn't to hand.

The SketchUp model can be downloaded from the Google 3D Warehouse.

Shadows in perspective

I have added an additional section to the 'How to...' page, showing a method for constructing shadows in perspective, or sciagraphical perspective, both in sunlight and for an artificial light source.

The illustrations come from Richard Brown's 'Principles of Practical Perspective' of 1815. Brown, who described himself as an architect and professor of perspective, dedicated his treatise to John Soane. The book contained 51 plates and was originally priced at two guineas.

"To enter into any laboured encomiums on the importance of Perspective, and the use of painting would be needless.  The absolute necessity of an intimate acquaintance with its principles and its practice, in order to arrive at excellence, or even mediocrity in the imitative arts, is now universally felt and acknowledged.  A practical treatise on Perspective and Painting needs, therefore, no apology."

(image copyright © Russell Light)