Agitation 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 natural 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 i.e. not by artificial light source. The area of a scene that a lens covers or sees.
Angle of view is determined by the focal length of the lens.
F11 Reflex Nikkor, only slightly over 1 degree of view. It can also be explained as the extent of the view taken in by a lens. For any particular film size, it varies with the focal length of the lens. Usually expressed on the diagonal of the image area. Having the ability to bring all colours of the visible spectrum to a common plane of focus, within close tolerances, usually refer to a lens with such superior colour correction.