Digital Photography & Photography History:

Beyond the Daguerrotype:

Many know of the Daguerrotype, used in the 1850's. Less know is how short a time the Daguerrotype was in use. It was replaced by a process that had better spectral sensitivity. Why? Because in the 1850 photographers worked with astronomers to get the first photographs of the moon and the planets. Amazingly, photography using the collodion process helped document a rare event in our solar system,  as early astrophotography teams photographed the Transit of Venus.

(Photo 1 at left)

Here, John Likes of Colorado and his wife use the
collodion process  ( gun cotton in alcohol and ether that forms a clear film on the glass after the solvents evaporate) , invented in 1856 by English sculptor named Frederick Scott Archer. In collodion, silver halides impervious to water are fixed on glass plates, as John has done with his portrait subjects. Inside a cloth- darkened area within a pole supported white teepee, setup on the plains in the wind, silver nitrate is poured onto the glass plate and ideally, dries smoothly. In reality it takes a lot of practice to pour the chemistry correctly.  The photographer then puts the glass plate inside a wooder carrier, the equivalent of a sheet film holder today, and this carrier attaches to the back of the heavy camera, and after pulling the famous dark cloth over his head, John  exposes the plate by pulling a dark slide away.

John Likes used exposures from 10 seconds at noon in the shade to longer exposures.   He has to expose the plate within about 15 minutes of coating the glass with the emulsion, though, and his plates have to be developed within about 15 minutes of exposure. Development occurs back in the teepee, and the plate is backed with black and framed, or printed on albumen paper coated with egg white giving it a glossy surface, the foundation of modern "glossy" papers.

Many know of William Henry Jackson's 20 x 24 glass plates that he used to photograph the American west. Carleton Watkins also photographed using glass plates that weighed 4 pounds each. His 2,000 pounds of photography gear came in handy, when they helped Yosemite Valley become a national park. Painters of the day often based their compositions on Watkins, Brady, and Jackson photographs, but photography was considerably influenced by painting.

William Henry Jackson once said that the time it took to make a photograph, starting from when the camera was pulled off the back of his mule and ending when it went back atop the mule, was a half hour.   The collodion process was 20 times faster than previous methods, and had no restrictive patents. Matthew Brady also used collodion to capture the Civil War, and this process is still used today for civil war re-enactment photography.  For Matthew Brady, documenting the emotion of the civil war as noone had done with photography before was a passion. Long prized for their value as historical documents, Brady's Civil War photographs initially did not sell, because after the war they were seen as unnecessary reminders of hardship and conflict . Dry plates were invented in the 1870's, and this gelatin dry plate let to the invention of the Kodak camera by George Eastman in 1888. Beautiful examples of this camera are on display in New York in Rochester at the George Eastman Intl. museum holding 400,000 photographs and negatives.
 
 

Transit of Venus : Ask an Astronomer

When the collodion process was invented, it was used to capture the Transit of Venus, as mathematicians and astronomers calculated the distance between the earth and the sun, and also the circumpherence of the earth. Every century or so, Venus makes two passes between us and the Sun -- about ten years apart. Unlike our Moon, which blots out the Sun, Venus is far away. Watch it through a dark glass and you see only a small black spot moving across the sun's disc. Venus blots out nothing, but that crossing, or transit, of the Sun gives the information we need to calculate the size of the solar system. This is written up in detail at the following link to work by David Sellars
in Leeds England.

When transits of Venus occur, they occur in pairs separated by 8 years. The last set of transits occurred in December 1874 and December 1882.

Ask the astromers! The next set of transits will occur on June 8, 2004, starting at approximately 1 AM, EST, and lasting until approximately 6 AM. (That is, on the East Coast it will be just ending at sunrise.) Another transit will occur on June 5, 2012, starting at approximately 5 PM EST and lasting until about midnight. So the East Coast will see the beginning of that one. The precise start times and duration of the transit depend upon one's location on the earth (reference, Jim Lochner, Imagine the Universe). The last transit occurred in 1882. For a fascinating look at the process of photographing it, click here for the 1882 Transit of Venus.

Thought Questions:

1) What do photography and astronomy have in common ?
2) How were photography and painting interconnected?
3) Name 3 ways photography was influenced by painting?
4)  Trick Question: What national park did photography help establish?
5) What are the similarities between computer digital imaging and wet plate photography?