Dichroic

Dichroic filters
Produced by metallic surface coatings on glass to form colours by interference of light. Used in high quality colour enlarger heads.
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Dichroic Filters Most photographic filters use colored dyes that absorb certain wavelengths and allow others to be transmitted. Such filters do not begin and end transmission at precise wavelengths.

Dichroic Enlarger: An enlarger equipped with dichroic filters for colour printing. Dichroic filter values are adjusted by turning dials normally located on the side or top of the enlarger.

dichroic filter
A light producing mechanism which concentrates and directs visible light but not infrared radiation (heat). Used in movie and multimedia production, and in some scanners. See scanner.
digital camera ...

dichroic color
property of having two peaks in the spectrophotometric reflectance curve causing it to respond differently to differnet light sources.

Dichroic
A vapor-deposited coating (usually on glass or metal) that reflects unwanted portions of the light spectrum. A filter with such a coating, typically one that converts tungsten light to match daylight sources or films.

Dichroic head
An enlarger head that contains yellow, magenta, and cyan filters that can be moved in calibrated stages into or out of the light beam to change the colour balance of the enlarging light.

-Dichroic - displaying two colors - one by transmitted and one by reflected light.
-Dichroic filters - produced by metallic surface coatings on glass to form colors by interference of light. Used in high quality color enlarger heads.

Dichroic Dichroic filters are interference filters at an angle of incidence of light of 45°. The transmissivity and reflectivity of dichroites depend on a specific wavelength of light.

A hot mirror is a specialized dielectric mirror, a dichroic filter, often employed to protect optical systems by reflecting infrared light back into a light source, while allowing visible light to pass.

I don't know that arrays of dichroic mirrors can be manufactured in the size we'd want for photography at all, or at a reasonable price. For all I know, Nikon might want to use these in their RGB meters, not at the taking image plane.

Some photographers have encountered dichroic fog (an ugly brown metallic stain) on sheet film processed in T-MAX developer. The new T-MAX RS developer-replenisher should eliminate this problem with sheet film.

My article on calibrating a dichroic enlarging head for use as a VCCE light source when printing on variable contrast black and white printing papers. This is an updated version of what appeared in Photo Techniques in February 1998.

See also: Light, Filter, Filters, Image, Lighting