Latensification
Encyclopedia
Latensification is the name given to uniformly pre-exposing a photographic emulsion
(film).
The benefits of latensification are applicable in astrophotography
- capturing images of stars. Without latensification an image would come out with several visible stars and be a perfectly acceptable image. However, many areas of the image would contain 'sub-latent' images, or areas of emulsion which have not received sufficient light to be exposed enough to show up. If the film was pre-exposed, the threshold point of exposure could be reduced, so these 'sub-latent' images could become visible. More simply, the stars which would normally be too dark to expose the film, would now be sufficiently bright to expose correctly.
In general photography, this process is often referred to as pre-exposure or pre-flashing
, and is used with both film
and paper
. It can provide greater control over lower values than simply decreasing the time the film spends in developer
, as well as enhancing the response of paper to low values during printing.
Photographic emulsion
Photographic emulsion is a light-sensitive colloid, such as gelatin, coated onto a substrate. In silver-gelatin photography, the emulsion consists of silver halide crystals suspended in gelatin, and the substrate may be glass, plastic film, paper or fabric....
(film).
The benefits of latensification are applicable in astrophotography
Astrophotography
Astrophotography is a specialized type of photography that entails recording images of astronomical objects and large areas of the night sky. The first photographs of an astronomical object were taken in the 1840s, but it was not until the late 19th century that advances in technology allowed for...
- capturing images of stars. Without latensification an image would come out with several visible stars and be a perfectly acceptable image. However, many areas of the image would contain 'sub-latent' images, or areas of emulsion which have not received sufficient light to be exposed enough to show up. If the film was pre-exposed, the threshold point of exposure could be reduced, so these 'sub-latent' images could become visible. More simply, the stars which would normally be too dark to expose the film, would now be sufficiently bright to expose correctly.
In general photography, this process is often referred to as pre-exposure or pre-flashing
Pre-flashing
In cinematography and photography, pre-flashing is the exposure of the film or other photosensor to uniform light prior to exposing it to the scene to be imaged...
, and is used with both film
Photographic film
Photographic film is a sheet of plastic coated with an emulsion containing light-sensitive silver halide salts with variable crystal sizes that determine the sensitivity, contrast and resolution of the film...
and paper
Photographic paper
Photographic paper is paper coated with light-sensitive chemicals, used for making photographic prints.Photographic paper is exposed to light in a controlled manner, either by placing a negative in contact with the paper directly to produce a contact print, by using an enlarger in order to create a...
. It can provide greater control over lower values than simply decreasing the time the film spends in developer
Photographic developer
In the processing of photographic films, plates or papers, the photographic developer is a chemical that makes the latent image on the film or print visible. It does this by reducing the silver halides that have been exposed to light to elemental silver in the gelatine matrix...
, as well as enhancing the response of paper to low values during printing.