Flare A streak or flaw on a photograph resulting from an undesirable light source or reflection. Flash A burst of light used to illuminate a photographic subject so that the image may be recorded on film. Properly used, a programmable automatic flash can be useful in many light conditions beyond basic darkness. For example, use the fill-in setting when your subject is in shadow, even on a bright day. The distance that a lens should be held from a screen in order to project a focused image on that screen.
Focal length dictates the angle of view.
The longer the focal length, the narrower the angle of view. Wide-angle lenses have short focal lengths typically 20mm, 24mm, and 35mm. Standard focal length lenses are 50mm and 80mm to 300mm are telephoto lenses. Focus Adjustment of the distance setting on a lens to define the subject sharply. Frame One picture on a roll of film.