Search results
Results from the WOW.Com Content Network
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.
Photosensitizers utilize light to enact a chemical change in a substrate; after the chemical change, the photosensitizer returns to its initial state, remaining chemically unchanged from the process. Photoinitiators absorb light to become a reactive species, commonly a radical or an ion, where it then reacts with another chemical species. These ...
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 ...
Apart from the widely employed factors such as log-exposure, density, opacity and transmission, sensitometric control of film for television transmission is also particularly concerned with contrast ratios. The definition of contrast ratio is therefore re-stated as follows : 'The ratio between the opacities of the darkest and lightest points in ...
A sensitizer in chemiluminescence is a chemical compound, capable of light emission after it has received energy from a molecule, which became excited previously in the chemical reaction. A good example is this: When an alkaline solution of sodium hypochlorite and a concentrated solution of hydrogen peroxide are mixed, a reaction occurs:
Photographic processing or photographic development is the chemical means by which photographic film or paper is treated after photographic exposure to produce a negative or positive image. Photographic processing transforms the latent image into a visible image, makes this permanent and renders it insensitive to light.
A demonstration of the effect of exposure in night photography. Longer shutter speeds result in increased exposure. The true characteristic of most photographic emulsions is not actually linear (see sensitometry), but it is close enough over the exposure range of about 1 second to 1/1000 of a second. Outside of this range, it becomes necessary ...
Advertisement for Ansco Cyko photographic paper, 1922. Photographic paper is a paper coated with a light-sensitive chemical, used for making photographic prints.When photographic paper is exposed to light, it captures a latent image that is then developed to form a visible image; with most papers the image density from exposure can be sufficient to not require further development, aside from ...