Panchromatic film

All infrared-sensitive materials must be loaded and developed in total darkness, as safelight screens, even those for panchromatic films and plates, transmit the infrared freely. 

In addition to different types of emulsions, there are different types of film. These include panchromatic films, which are sensitive to all colors of visible light to varying degrees (these include all those films mentioned in the previous section) orthochromatic films, which are primarily blue-sensitive infrared films, which record in the infrared or near-infrared spectrum document films, which are extremely high in contrast exhibiting little or no mid-tones unless... 

As panchromatic film choices have narrowed, so too have choices in alternative films. Current orthochromatic films include Adox 25 ORT and Rollei Ortho 25 . Infrared films... 

Almost any panchromatic film made today can be pushed one stop with little or no discernible loss in quality. For example, Kodak Tri-X can easily be pushed to El 800 and Ilford Delta 3200 (which is closer to El 1200 than it is to ISO 3200) can easily be pushed one stop to El 2400. Try adding 25% to the normal development time for Tri-X, and 25% to 40% with other films for a one stop push. With testing and experience, you should be able to capture almost any event on film, regardless of how little ambient light is present. (See Yuette at the Coffee House on page 53 )... 

Both the transmission and reflection methods work equally well with any panchromatic film. Using either method, as many sheets of film as can be safely handled at once can be developed. When a film is fully developed it should be moved into a holding acid stop bath or running-water rinse where it can be left until the other films catch up at which time they can all... 

The first panchromatic film, able to render the image of a scene realistically into black and white, followed on the work of Vogel in Berlin after 1873, [2] in which he associated dyes with the halide semiconductor grains. The first sensitization of a photoelectrode was reported shortly thereafter, using a similar chemistry [3]. However, the clear recognition of the parallels between the... 

The silver hafides are sensitive mainly to blue, violet, and ultraviolet light hence, without sensitization, positive photographs reproduce all other colors as dark grays or blacks. However, by the addition of certain dyes to the emulsion, increased sensitivity to the other colors is obtained. Thus, panchromatic films, in which sensitivity is extended throughout the visible spectimn. 

Figure 2 shows a fogging curve of film exposed to y radiation over the top of a core (130-150 rads/hr) for various times. (Note that the orthochromatlc, film Gravure Positive does not obey equation (1) and has. In fact, a much worse radiation performance than panchromatic films). 

This may not be the place to deal with the various photographic emulsions. Moreover, infrared, black-and-white or color films do not deserve special explanations. We should remember, however, that the power of infrared-sensitive emulsions does not, practically speaking, extend beyond 0.9 jum. It is not advisable to expose infrared film without a filter, as in this case, results are far superior with normal black-and-white or color panchromatic films. 

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