How to Take Glass Plate Photos
Glass plates are placed in plate holders (light-tight containers) to prepare them for use. The transfer of these plates into their holders requires complete darkness. Hartman would have been forced either to do this in a dark tent, or wait until nightfall.
After the camera is attached to a tripod, the lens is opened and...
...the camera is focused on the object or scene to be photographed.
Keep in mind, the 'focused' image that is seen through the lens is actually upside-down and reversed!
The lens is closed and the glass plate holder is carefully inserted into the camera.
The dark slide (a light-tight sheet in the plate holder that covers the glass plate before exposure) is removed and...
...the lens is opened to expose the glass plate to light. Once the glass plate is sufficiently exposed, the dark slide is returned to the plate holder (flipped to identify the plate as exposed).
The glass plate holder (with exposed plate inside) is removed from the camera and is ready for development at any time.
This was repeated for EACH glass plate negative. Such an involved procedure left many opportunities for error:
- Glass plates were frequently loaded backwards into the camera, with the emulsion side facing away from the lens (resulting in an inverted image when the photograph was printed).
- The lens was not closed before loading the plate (resulting in an overexposed image).
- The plate holders were not properly marked after exposure and would consequently be re-used (resulting in a double exposure).
Special thanks to Jim Burke at the Photographic & Electronic Imaging Services, University of Pittsburgh.
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