Clayden effect

Derived from experiments described by A. W. Clayden.

Clayden effect (plural Clayden effects)

1. (photography) A dark streak that appears in a photograph when there has been a very brief flash of intense light, such as a stroke of lightning, while the photographic plate is being exposed. This effect is caused by the flash causing the part of the photographic plate exposed to the intense light less sensitive, so that it is less affected than the surrounds during the rest of the exposure.
   • 1910 April, Wilder D. Bancroft, “The Electrochemistry of light”, in The Journal of Physical Chemistry, volume 14, number 4, page 306:

     After I had established in this way the similarity between the action of electrical discharges and of the Röntgen rays, it was very important to determine whether here, as in the Clayden effect, it was a matter of the brief but intense light action of the spark or whether perhaps some special electrical property was the determining factor.

   • 1975, Coherent Optical Processing: Seminar, page 56:

     Other important film effects such as reciprocity failure and intermittancy ^[sic], adjacency effects, Herschel effects, solarization effects, and Clayden effects have not been considered in the simple discussion presented here, […]

   • 2022, Leonard B. Loeb, Electrical Coronas: Their Basic Physical Mechanisms, page 190:

     This is an example of the Clayden effect shown by certain photographic emulsions. It is seen much more clearly on the negative, or in direct traces on an opaque film of the light of a more sensitive emulsion.