TheAncestorFiles: The Tanner Family Daguerreotype: What is a Daguerreotype?

Wednesday, March 7, 2012

The Tanner Family Daguerreotype: What is a Daguerreotype?

The history of photography is too complicated to describe here, but the first photographic images of people were created in 1838 or 1839, just a few years before the Tanner daguerreotype was taken. It was a technology whose time had come: it quickly became widespread within a few years.

Here is the picture of the first known photographic image that shows living people. The picture was taken with a ten-minute exposure, so the only people who show up are a man getting his shoes polished, and the shoe-shine boy, who didn't move for much of that time. (Look in the bottom left corner.)

From Wikipedia.

This picture was created by Frenchman Louis Daguerre, the man who developed the process known as daguerreotype. There were many other processes being developed about the same time; William Henry Fox Talbot made major contributions to the technology.

The daguerreotype process is complicated:

The daguerreotype is a direct-positive process, creating a highly detailed image on a sheet of copper plated with a thin coat of silver without the use of a negative. The process required great care. The silver-plated copper plate had first to be cleaned and polished until the surface looked like a mirror. Next, the plate was sensitized in a closed box over iodine until it took on a yellow-rose appearance. The plate, held in a lightproof holder, was then transferred to the camera. After exposure to light, the plate was developed over hot mercury until an image appeared. To fix the image, the plate was immersed in a solution of sodium thiosulfate or salt and then toned with gold chloride.

Exposure times for the earliest daguerreotypes ranged from three to fifteen minutes, making the process nearly impractical for portraiture. Modifications to the sensitization process coupled with the improvement of photographic lenses soon reduced the exposure time to less than a minute.

Although daguerreotypes are unique images, they could be copied by redaguerreotyping the original. Copies were also produced by lithography or engraving. ("The Daguerreotype," Library of Congress.)

A daguerreotype was taken by a camera with the lens in a sliding compartment. The daguerreotype artist focused the picture by sliding the rear compartment of the box forward or backward. The daguerreotype was a mirror image unless the image was flipped by a mirror or prism. The artist took the picture by putting a plate into the camera, and then removing the lens cap to expose the plate.

Daguerreotypes came in several standard sizes:

Whole plate          6.5 x 8.5 inches
Half plate                4.25 x 5.5 inches
Quarter plate           3.25 x 4.25 inches
Sixth plate               2.75 x 3.25 inches
Ninth plate        2 x 2.5 inches
Sixteenth plate        1.375 x 1.625 inches

A daguerreotype was typically placed in a case and a brass protector, then covered with glass, a brass mat, and a paper seal. (Christopher Warren.)