Equipment and Process
The cameras that Lytle had to work with in the course of his career were bulky, heavy, and required specialized knowledge to operate. There were no “point-and-shoot” cameras until the late 1880s and even then few people could afford them. Almost all photographic images before then were created by professional photographers.
When a photograph was made, the image fell on a glass plate negative that had been prepared using the wet-plate collodion process, which not only required special knowledge but timely action. The plate had to be prepared, exposed, and developed while the collodion remained wet.
Photographic collodion is a mixture of raw cotton treated with nitric and sulfuric acids and then dissolved in ether and alcohol, with a little iodide and bromide mixed in. The solution is transparent and sticks to nearly everything. To make photographs using this wet-plate collodion process, the photographer:
- Pours the collodion onto a glass plate and then tilts the plate to evenly coat the entire surface with the solution. Any excess collodion is poured back into its bottle.
- Moves into the darkroom (or, if in the field, the dark tent). While the plate is still wet, he dips it into a solution containing silver nitrate. The silver nitrate binds with the iodide and bromide to make a silver halide coating, which is sensitive to light. Excess silver nitrate solution is wiped off the back of the plate with a clean cloth.
- Inserts the still-wet plate into a lightproof holder, takes the holder to the camera and inserts it. The silver nitrate solution often drips from the holder even when in the camera. The photographer then removes a slide in the holder that covers the glass plate, making the collodion plate ready for exposure.
- Removes the lens cap and exposes the plate by allowing light to enter the camera and strike the light-sensitive collodion. Plate exposure times range from 20 seconds to five minutes.
- Replaces the lens cap to end the exposure.
- Reinserts the holder’s slide so that the holder can be removed from the camera without further exposing the plate and takes the holder back to the darkroom or dark tent.
- Removes the glass plate from the holder, and while holding the plate over a tray, pours developer over the plate. The developer is a solution of iron sulfate and acetic acid. It turns the silver-halide grains that have been struck by light into metallic silver. The glass plate is rinsed with water to remove the developer. At this point, the plate can be taken from the dark room.
If Lytle went into the field to shoot, he had to bring not only the camera and tripod but also a portable darkroom (or a fast horse to get the plate back to town before it dried out). Exposure times were relatively long and the slightest movement by the subject or the camera meant a wasted shot.
Very few glass plate negatives made by Lytle have survived. Photographic prints of the images on these plates have been created from a modern internegative, which is more stable and robust than the original glass plate negative. To help protect the original glass plates that do survive, any future prints will be made from the internegative rather than the glass plate.