- 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.
- Hand coloring - process of applying color tints, in the form of paint, to a photographic image to create or enhance the color effect.
- Hard gradation - term denoting the quality of harsh contrast in a photograph.
- 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 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.
- 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.
- 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.
- Hypo eliminator - chemical bath which removes traces of fixing agent from an emulsion.