Developing_tank
A developing tank is a light-tight container used for developing film.[1] A developing tank allows photographic film to be developed in a daylight environment. This is necessary because most film is panchromatic and therefore can not be exposed to any light during processing.[2] Depending upon the size and type, a developing tank can hold one to many roll or sheet films. Famous brands include Paterson, Yankee, Jobo and Nikor.
A film reel holds roll films in a spiral shape. The film is held evenly spaced so that the chemicals in the developing tank reach all of the film.