Fox Talbot's interest in photography
was sparked in 1833 when using a camera obscura to draw, his mind was set
to pondering to a means of recording the image chemically. In Fox Talbot's
process, paper was coated with chemicals to make it light sensitive, the
preparation of the photographic paper needed to be completed shortly before
use, as it would not keep for many days. Once made it was placed in the
camera and exposed in the normal way. In his earlier experiments the exposure
was continued until the image appeared on the paper simply as a result of
continued reaction. However, this was unacceptably long and Fox Talbot found
that in common with the Daguerreotype system a "latent" image existed after
a short exposure and this could be made visible with treatment - development.
After this the paper needed to be "fixed" to prevent the image continuing
to process until obliterated by the action of light. This could be done
in a saturated solution of common salt. The result would be a negative image
on paper, which when placed against another similarly treated sheet of paper
and exposed through the back, would create a positive. The name of this
process was Calotype. Any number of rather grainy copies could be generated
from the first sheet, in this respect it had the advantage over the Daguerreotype
system which created a single positive original. The Calotype system did
not enjoy quite the commercial success of the Daguerreotype, but it pointed
the way for the future and can rightly be regarded as the beginning from
which modern photography came. |