hypersensitization

Photographic hypersensitization refers to a set of processes that can be applied to photographic film or plates before exposing.

Some of the earliest gas-phase hypersensitization methods involved exposing the plates to mercury vapor before exposure to light.

This was an extremely fine-grained, high-contrast, extended-red-sensitivity panchromatic film that benefited dramatically from hypersensitization.

Several hypersensitization or "hypering" techniques have been developed to overcome this failure of the reciprocity law, and what follows refers mainly to work in astronomy.

The hyperactive state in the former condition suggests the development of denervation hypersensitization even though the neurons interrupted are preganglionic rather than postganglionic.

Hypersensitization was also used, and can still be used, with other black-and-white materials and with color films, especially the Kodak Ektachrome line.

Hypersensitization is used particularly in deep-sky astrophotography, which deals with low-intensity incoming light, requires long exposure times, and is thus particularly sensitive to contaminants in the film.

Also present is a research-grade CCD imaging system, an 8-inch Schmidt camera, photoelectric photometers, an image intensifier, and a darkroom with film hypersensitization facilities.

"Chronic pain actually changes the way the spinal cord, nerves, and brain process unpleasant stimuli causing hypersensitization, but the brain and emotions can moderate or intensify the pain."

It is used in chambers for gas hypersensitization, a process in which photographic film is heated in forming gas to drive out moisture and oxygen and to increase the base fog of the film.

Gas hypersensitization is the process of soaking or flushing the photographic film or plate for an extended period of time in nitrogen, hydrogen, or a hydrogen/nitrogen mixture called forming gas, sometimes with heating.

Hypersensitization with forming gas or hydrogen was widely used by professional astronomers on plates and by amateur astronomers on film up until the wide adoption of CCD astronomical cameras relieved them of the tedium.

Hypersensitization techniques are intended to lengthen the lifetime of the unstable sub-latent image, to increase the chances of the silver halide crystal receiving enough light to form an image that will catalyze the action of the developer.

Spectroscoptic studies of the planet Venus were carried out by JPL astronomers, Andrew and Louise Young, with Jim Young assisting with hypersensitization of Eastman Kodak IR spectroscoptic glass plates.

Some progress was made in the field of photographic emulsions and in the techniques of forming gas hypersensitization, cryogenic cooling, and light amplification, but starting in the 1970s after the invention of the CCD, photographic plates have given way to electronic imaging in professional observatories.