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For example, for a given film, if a light meter indicates a required EV of 5 and the photographer sets the aperture to f/11, then ordinarily a 4-second exposure would be required; a reciprocity correction factor of 1.5 would require the exposure to be extended to 6 seconds for the same result. Reciprocity failure generally becomes significant ...
Photographic emulsion is a light-sensitive colloid used in film-based photography. Most commonly, in silver-gelatin photography , it consists of silver halide crystals dispersed in gelatin . The emulsion is usually coated onto a substrate of glass , films (of cellulose nitrate , cellulose acetate or polyester ), paper, or fabric.
Exposure is a combination of the length of time and the illuminance at the photosensitive material. Exposure time is controlled in a camera by shutter speed, and the illuminance depends on the lens aperture and the scene luminance. Slower shutter speeds (exposing the medium for a longer period of time), greater lens apertures (admitting more ...
A developable photographic latent image forms when crystals of silver halide in an emulsion layer are exposed to light. The initial nucleation phase is chemically and thermodynamically unstable; it is thus temperature sensitive, and involves the production of one, or very few silver atoms as sub-latent image specks in each silver halide crystal.
If the EV is known, it can be used to select combinations of exposure time and f-number, as shown in Table 1. Each increment of 1 in exposure value corresponds to a change of one "step" (or, more commonly, one "stop") in exposure, i.e., half as much exposure, either by halving the exposure time or halving the aperture area, or a combination of ...
An example of a black and white developer is Kodak D-76 which has bis(4-hydroxy-N-methylanilinium) sulfate with hydroquinone and sodium sulfite. In graphic art film, also called lithographic film which is a special type of black and white film used for converting images into halftone images for offset printing, a developer containing methol ...
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This reduces photographic speed and contrast. This is common with emulsions optimized for highest sensitivity with long exposure using old emulsion technology. HIRF is due to creation of many latent subimages that are not developable due to small size. Because of brief and intense exposure, many photoelectrons are created simultaneously.