"H"-Format:- One of the three selectable Advanced Photo System print formats; identical to the 9:16 aspect ratio used in high-definition television (HDTV); suitable for wider shots than usual, such as groups; produces prints of 3.5 x 6 inches or 4 x 7 inches. See also Aspect Ratio and Interspersed Aspect Ratio.
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.
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 ¾ x 6 ½ 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.
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.
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.
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.
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.
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:- The fitting on a camera that holds a small portable flash. It has an electrical contact that aligns with the contact on the flash unit's "foot" and fires the flash when you press the shutter release. This direct flash-to-camera contact eliminates the need for a PC cord.
Hot spot:- often undesirable concentration of the central beam of a flood or spotlight on the subject.
Hue:- name of the color (e.g. red, blue, yellow).
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.