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. 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 is a method of increasing the light sensitivity of a photographic emulsion prior to exposure. Hypo is the 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 is a chemical bath which removes traces of fixing agent from an emulsion.