William Henry
Fox Talbot born 1800 died 1877.
Fox Talbot was
considered a polymath some of his interests and qualifications
included Philosophy, Mathematics, Physics, Egyptology, Philology,
Syrian, Chaldean cuneiform text and photography. Fox Talbot carried
out his experiments at the family home which was Laycock Abbey
Wiltshire.
 |
| Fox Talbot's sketch of Lake Como using camera obscura. |
Fox Talbot
started looking in earnest for a way to fix an image to paper in
1834; he would first have to find a paper that could be submerged in
a solution of salt and silver nitrate without it disintegrating. The
result of combining these two chemicals would make silver nitrate a
light-sensitive salt that was not affected by the moisture in the
paper. He now had a paper that could be used for photogenic drawing.
The first pictures he produced were of leaves
and
lace. He placed these on a sheet of light-sensitive paper and put
a sheet of glass over them, then left them out in the sun.
Fox Talbot used
many different types of camera to produce his pictures. There we a
couple of cameras or boxes that only measured two or three inches
which Fox Talbot left around the grounds of Laycock Abby in different
places with light-sensitive paper in for about an hour at a time.
They were nick named mouse traps by the family. His early cameras
would use telescope or microscope lenses.
This is the
picture
of the famous Oriel window in the south gallery of Laycock Abby. It is
the earliest surviving paper negative dated 1835. when originally
taken you could count the two hundred tiny pieces of glass that made
up the window with the help of a lens. This is a replica of the
camera
he used to take the Oriel window shot.
By chance in 1840
Fox Talbot discovered when re-sensitizing some paper that the image
had appeared; this became known as the latent image. Before this time
he was having trouble with the sensitivity of the papers. Although he
had been able to fix the images by using a strong salt solution of
potassium iodine of hypo to stop the images fading. This new
discovery was a major break through that meant exposures could be
achieved in one to three minutes instead of half hour or more. The
year after Fox Talbot discovered how to make his photogenic drawing
process more sensitive to light by adding Gallic acid to the process.
He also found that a further treatment of Gallic acid and silver
nitrate would bring the latent image out. It was time he changed the
name of the process to Calotype (from the Greek "Kalos"
meaning beautiful) the Calotype was a negative/positive
process introduced in 1841. Strictly speaking Calotype should
have referred to the Positive part of the process.
The advantages of
the calotypes
were unlimited prints from one negative, retouching could be done
to the negative or print, the paper print was easier to see and could
be handled with out damage and had warmer tones.
Some of the draw back of this process were that prints tended to fade; fibers in the paper reduced the quality of the print, making the focus soft but some people found this an advantage. Materials were less sensitive to light needing longer exposure.
For more information:
