Photography glossary - H
Hand-held exposure meter - External exposure meter.
Halation - diffused ring of light typically formed around small
brilliant highlight areas in the subject. It is caused by light passing
straight through the emulsion and being reflected back by the film
base on the light sensitive layer. This records slightly out of register
with the original image.
Halogens -a group of chemical elements. In photography, three
of these, bromine, chlorine and iodine are used with silver to
produce light sensitive material.
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Half-frame - negative format of 18 x 24mm. Images are recorded
on a vertical axis on standard 35mm film, thus giving 72 half-frame
images on film designed for 36 exposures.
Half-frame camera - camera designed to use 35mm film in a half-
frame format.
Half-plate - picture format measuring 4 3â„4 x 6 1â„2 inches. Some
early cameras produced negatives of this size.
Half-silvered mirror is a glass sheet evenly coated with a
substance which transmits part of the light incident on it and
reflects the remainder. Used for beam splitting devices in
holography, and for front projection.
Halftone - mechanical process for printing continuous tone
images in ink.
Halogens - collective term for the elements chlorine, bromine and
iodine, which are combined with silver to produce the light
sensitive crystals used as the basis for photographic emulsions.
Hand coloring - process of applying color tints, in the form of
paint, to a photographic image to create or enhance the color
effect.
Hanger - frame for holding sheet film for processing.
Hard - defines a scene, negative or print with high contrast.
Hard drive /disk - Device for the permanent storage of programs and information that remain after a computer has been turned off.
Hardeners - chemicals often used with a fixing bath to strengthen
the physical characteristics of an emulsion. The most common
hardeners are potassium or chrome alum.
Hard gradation - term denoting the quality of harsh contrast in a
photograph.
HDD - Hard Disc Drive.
Heat filter - optical attachment made of thick infrared absorbing
glass, used to absorb heat radiation from alight source without
diminishing output.
Heliography - early photographic process invented by Niepce,
employing a polished pewter plate coated with bitumen of Judea.
Herschel effect - the destruction of an exposed image by infrared
radiation.
Hide - camouflaged barrier used by natural history and wildlife
photographers.
High art photography - general term for an early form of artistic
photography (1851-1870), in which photographers set out to match
the style and subject matter of paintings of the period.
Hi Colour - Describes an image having at least 32,000 colours.
High contrast developer - solutions used to produce high
contrast images.
High key - photograph which contains large areas of light tones,
with few middle tomes or shadows.
Highlights - the brightest ares of the subject, represented on a
negative by dense deposits of black metallic silver, but reproducing
as bright areas on the positive print.
Hill cloud lens - lens with a 180° angle of view, used for
photographing cloud formations and other meteorological work.
Histogram – A graphic representation of the range of tones from dark to light in a photo. Some digital cameras include a histogram feature that enables a precise check on the exposure of the photo.
Holding back - 1. Shortening the development time given to film
to help reduce image contrast. 2. Method of decreasing exposure
given to selective areas of the print. Also referred to as dodging.
Holography - system of photography, using neither a camera not
lens, in which laser beams create an interference patter recorded
directly on appropriate light sensitive sheet film or plates. After
processing, viewing the image by the light of a laser gives a three
dimensional image.
Homepage - First page of an internet site.
Horizon - line at which earth and sky appear to meet. Its position,
which can be altered by titling the camera or by cropping the image
determines whether the sky or the landscape concentrates interest
in the picture. A low horizon (tilting the camera up) concentrates
interest in the sky while a high horizon (tilting the camera down)
concentrates interest in the landscape.
Hot Shoe A flash connector generally found on the top of the camera that lets you attach a flash unit and trigger it in sync with the shutter.
Hot spot - often undesirable concentration of the central beam of
a flood or spotlight on the subject.
Hot plugging - The connection and uncoupling of external devices while the PC is running. Restarting the computer is unnecessary. Requirements: →USB, and the relevant operating system. (Plug and Play)
html - Hypertext markup language, a file format used in the →World Wide Web.
http - Hypertext transfer protocol: transmission format and communication basis for the exchange of data in the internet.
Hue - name of the color (e.g. red, blue, yellow).
Hunting An autofocus system that has trouble finding the focus in an image so that the system moves in and out of focus continuously, "hunting" for the correct focus point.
HQ-resolution - High Quality-resolution. Description for high digital photo quality.
Hydrobromic acid - acid liberated during the developing process
by the reduction of bromide.
Hydrochloric acid - chemical used in some bleaching solutions.
Hydrogen peroxide - chemical used in hypo clearing agents.
Hydroquinone - reducing agent. It is used in developers to
provide high contrast results in the presence of a strong alkali.
Hyperfocal distance - distance between the camera and the
hyperfocal point.
Hyperfocal point - nearest point to the camera which is
considered acceptably sharp when the lens is focused on infinity.
When a lens is focused on the hyperfocal point, depth of field
extends from a distance halfway between this point and the
camera to infinity.
Hypersensitizing - method of increasing the light sensitivity of a
photographic emulsion prior to exposure.
Hypo - common name for a fixing agent, derived from an
abbreviation of hyposulfite of soda, the misnomer applied to
sodium thiosulfate during the 19th century.
Hypo eliminator - chemical bath which removes traces of fixing
agent from an emulsion.
