Keeping the developer, stop bath, or fixer in a gentle, uniform motion while processing film or paper. Agitation helps to speed and achieve even development and prevent spotting or staining. The available light completely surrounding a subject. Light already existing in an indoor or outdoor setting that is not caused by any illumination supplied by the photographer. The area of a scene that a lens covers or sees.
Angle of view is determined by the focal length of the lens.
Aperture Lens opening. The opening in a camera lens through which light passes to expose the film. The size of aperture is either fixed or adjustable. An exposure mode on an automatic or autofocus camera that lets you set the aperture while the camera sets the shutter speed for proper exposure. If you change the aperture, or the light level changes, the shutter speed changes automatically.