Camera lucida

[1][2] [3] The basic optics were described 200 years earlier by the German astronomer Johannes Kepler in his Dioptrice (1611), but there is no evidence he constructed a working camera lucida.

[4] There is also evidence to suggest that the Elizabethan spy Arthur Gregory's 1596 "perspective box" operated on at least highly similar principles to the later camera lucida, but the secretive nature of his work and fear of rivals copying his methods led to his invention becoming lost.

[6] While on honeymoon in Italy in 1833, the photographic pioneer William Fox Talbot used a camera lucida as a sketching aid.

He later wrote that it was a disappointment with his resulting efforts which encouraged him to seek a means to "cause these natural images to imprint themselves durably".

In 2001, artist David Hockney's book Secret Knowledge: Rediscovering the Lost Techniques of the Old Masters was met with controversy.

Their evidence is based largely on the characteristics of the paintings by great artists of later centuries, such as Ingres, Van Eyck, and Caravaggio.

[citation needed] In the simplest form of camera lucida, the artist looks down at the drawing surface through a glass pane or half-silvered mirror tilted at 45 degrees.

[9] Of particular concern is distortion, and new digital methods are being introduced which can limit or remove this, "computerized techniques result in far fewer errors in data transcription and analysis than the camera lucida procedure".