Actinic light
Encyclopedia
Actinic light is either light that affects photographic film
, or will facilitate photosynthesis
or stimulate light sensitive species.
to distinguish light that would expose the monochrome films from light that would not. A non-actinic safe-light (e.g. red or amber) could be used in a darkroom
without risk of exposing (fogging) light-sensitive films, plates or papers.
Early 'non colour-sensitive' (NCS) films, plates and papers were only sensitive to the high energy end of the visible spectrum
from green to UV. This would render a print of the 'red' areas as a very dark tone. Such light was actinic light. Yellow and red light was non-actinic. Xenon flash lamps are generally highly actinic, as is daylight.
In the first half of the 20th century, developments in film technology
produced films (orthochromatic and panchromatic) sensitive to red and yellow light and extended that through to near infra-red light. These gave a truer equivalent rendering of colour (hue) as a light, medium or dark tone, according to how we believe the human eye experiences it.
In photography, therefore, actinic light must now be referenced to the photographic material in question.
industry. They are used to promote coral and invertebrate growth.
They are also used to accentuate the fluorescence of fluorescent fish.
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...
, or will facilitate photosynthesis
Photosynthesis
Photosynthesis is a chemical process that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight. Photosynthesis occurs in plants, algae, and many species of bacteria, but not in archaea. Photosynthetic organisms are called photoautotrophs, since they can...
or stimulate light sensitive species.
Photography Use
The term was first commonly used in early photographyPhotography
Photography is the art, science and practice of creating durable images by recording light or other electromagnetic radiation, either electronically by means of an image sensor or chemically by means of a light-sensitive material such as photographic film...
to distinguish light that would expose the monochrome films from light that would not. A non-actinic safe-light (e.g. red or amber) could be used in a darkroom
Darkroom
A darkroom is a room that can be made completely dark to allow the processing of light sensitive photographic materials, including photographic film and photographic paper. Darkrooms have been created and used since the inception of photography in the early 19th century...
without risk of exposing (fogging) light-sensitive films, plates or papers.
Early 'non colour-sensitive' (NCS) films, plates and papers were only sensitive to the high energy end of the visible spectrum
Visible spectrum
The visible spectrum is the portion of the electromagnetic spectrum that is visible to the human eye. Electromagnetic radiation in this range of wavelengths is called visible light or simply light. A typical human eye will respond to wavelengths from about 390 to 750 nm. In terms of...
from green to UV. This would render a print of the 'red' areas as a very dark tone. Such light was actinic light. Yellow and red light was non-actinic. Xenon flash lamps are generally highly actinic, as is daylight.
In the first half of the 20th century, developments in film technology
Technology
Technology is the making, usage, and knowledge of tools, machines, techniques, crafts, systems or methods of organization in order to solve a problem or perform a specific function. It can also refer to the collection of such tools, machinery, and procedures. The word technology comes ;...
produced films (orthochromatic and panchromatic) sensitive to red and yellow light and extended that through to near infra-red light. These gave a truer equivalent rendering of colour (hue) as a light, medium or dark tone, according to how we believe the human eye experiences it.
In photography, therefore, actinic light must now be referenced to the photographic material in question.
Medical Use
Actinic is also applied to medical conditions triggered off by exposure, or excessive exposure to light, especially UV light.Aquarium Use
Actinic lights are also common in the reef aquariumReef aquarium
A reef aquarium or reef tank is an marine aquarium that prominently displays live corals and other marine invertebrates as well as fish that play a role in maintaining the coral reef environment...
industry. They are used to promote coral and invertebrate growth.
They are also used to accentuate the fluorescence of fluorescent fish.