In the first half of the 20th century, developments in film technology produced films sensitive to red and yellow light, known as orthochromatic and panchromatic, and extended that through to near infra-red light.
32.
These early products, described as " isochromatic " or " orthochromatic " depending on the manufacturer, made possible a more accurate rendering of colored subject matter into a black-and-white image.
33.
Named by the United Kingdom Antarctic Place-Names Committee ( UK-APC ) in 1960 for Hermann W . Vogel ( 1834 1898 ), German chemist who introduced the first orthochromatic emulsion for photographic plates in 1903.
34.
This will, however, require longer exposure ( and change the resulting image ) . ( This is only true with panchromatic black-and-white film, since orthochromatic film is already sensitive to only a limited spectrum .)
35.
The orthochromatic negative ended up reversed from the normal handedness, but as the two negatives were often contact-printed onto one duplitized film for subsequent colour-toning, as in the Prizma process, this often worked to the advantage of the laboratory.
36.
When using a film whose spectral sensitivity is not a good match to that of the light meter, for example orthochromatic black-and-white or infrared film, the meter may require special filters and re-calibration to match the sensitivity of the film.
37.
The old orthochromatic film stock of the early days was less discriminating about a person's color, as were black and white stocks in general, permitting some African-American actors a break, as their " color " was washed out or less obvious when photographed in black and white.
38.
The progression of lens design for later emulsions is of practical importance when considering the use of old lenses, still often used on large-format equipment; a lens designed for orthochromatic film may have visible defects with a color emulsion; a lens for panchromatic film will be better but not as good as later designs.
39.
On early 20th century and older orthochromatic ( blue-sensitive ) photographic film, the relative brightnesses of the blue supergiant Rigel and the red supergiant Betelgeuse irregular variable star ( at maximum ) are reversed compared to what human eyes perceive, because this archaic film is more sensitive to blue light than it is to red light.
40.
The strips would be adhered to a board, usually a stiff white paper on which the artist would draw the publication's margins and columns, either lightly in pencil or in non-photographic blue ink, a light cyan color that would be ignored by the orthochromatic film used to make printing plates in offset lithography.
