A half plate glass Paget colour taking screen, one of two colour screens used to make Paget ...

A half plate glass Paget colour taking screen, one of two colour screens used to make Paget colour transparencies. The Paget colour system was first introduced in 1912. This colour screen, a geometric matrix of very small red, green and blue colour filters, was used to provide the colour information when making a Paget black and white negative. The taking screen was held screen side in close contact with the emulsion side of a panchromatic black and white negative in a modified negative holder that could accept two pieces of glass and positioned in the camera so that the screen was between the negative and the lens. When the camera shutter was activated the image recorded on the black and white negative had to pass first through the colour screen before exposing the negative behind. The exposed negative was developed and a contact print made on another piece of glass. A viewing screen was then introduced, screen side to the emulsion side of the positive, and registered so that the screen was in exactly the same position as the taking screen. If the taking screen was registered correctly a colour image should result. This early colour system was only made possible with the development of panchromatic emulsions that could record the whole colour spectrum. Typical black and white emulsions of this period were orthochromatic, very blue sensitive and not sensitive at all to the red end of the spectrum. Although panchromatic emulsions could record the whole colour spectrum they were still very blue sensitive and photographers using Paget screens to make a glass colour transparencies would typically use a yellow filter to help balance the colour information recorded on the black and white negative. This was also common practice when exposing Autochromes. As panchromatic emulsions of the time were very slow, typically not faster than the equivalent of 10 to 12 ASA, exposures were measured in seconds and movement was a serious problem. To help overcome this problem the Paget system used two screens, a taking screen of much less colour intensity that permitted more light to reach the negative and a viewing screen to be attached to the positive of more intense colour.

• A half plate glass Paget colour viewing screen, one of two colour screens used to make Paget ...