Horizon is the 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. Hot shoe is a fitting on the top of many cameras designed to hold accessories, such as a flash gun. Hot spot is an often undesirable concentration of the central beam of a flood or spotlight on the subject. Hydrobromic acid is an acid liberated during the developing process by the reduction of bromide.
Hydrochloric acid is a chemical used in some bleaching solutions.
Hydrogen peroxide is a chemical used in hypo clearing agents. Hydroquinone is a reducing agent. It is used in developers to provide high contrast results in the presence of a strong alkali. Hyperfocal distance is the distance between the camera and the hyperfocal point . Hyperfocal point is the nearest point to the camera which is considered acceptably sharp when the lens is focused on infinity.