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|Roger touched on the original pinhole camera, or camera obscura
which apparently started being used by European artists in the 15th century
(see David Hockney's "Secret Knowledge").
The camera obscura inverts the image so that right-handed objects appear left-handed. It was soon realised that if the image is cast onto a translucent screen and viewed from the back, it is inverted and flipped left to right, and handedness is preserved.
The use of a lens makes it possible to have a larger hole, admitting more light, without losing sharpness.
|The camera lucida was a portable development, invented by William
Woolaston in 1807, when the properties of a prism began to be understood. The
crucial feature is that there are two internal reflections of the image of the
The eye is placed carefully (by looking through a small hole) so that half of the pupil is looking at the paper/pencil and half at the subject. The eye then sees pencil and subject superimposed on the paper, where it can be drawn.
|The camera lucida allows very rapid and accurate drawing. It
revolutionises the perspective representation of, for example:
the distortion of patterns on clothing,
very awkward shapes, including in particular awkwardly aligned regular ones, wrongly-drawn versions of which "do not look right"
shine and highlights.
The white on black sketches below were each one or two minutes work.
|The camera lucida has been used by many famous artists to ensure
correct landscape and portrait perspective. It permits people with no artistic
skill (explorers, for example) to make accurate landscape and even wildlife
drawings and has been used as a scaling tool (for example to reduce the very
large Audubon paintings to a size suitable for publication in "Birds of
Because the optical aperture is small the images tend to be rather faint. So the object should be strongly lit and the paper less so. This leads to a preference for tinted paper and for sunny days with the paper in shadow.
|The size of a drawn object is proportional to the distance of the
paper from the eye and this is limited by the length of the user's arm. For a
lifesize still-life or portrait the object needs to be the same distance from
the eye as the paper.
Roger uses a development of the camera lucida which does away with the need for the eye to be so accurately placed, above the centre of the paper and with the object at a right angle to it. This is done by half-silvering the face of the prism so that one of the two internal reflections is from the half-silvered surface and the object is viewed through the same surface.
|In the second half of the evening we all had the opportunity to try
out the three examples of the camera lucida that Roger had brought along - one
set up for portraits, one for still life and one for copying an existing
A most interesting evening. For more information
call 0118 959 6704
or email firstname.lastname@example.org
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