A film plane is the area inside any camera or image taking device with a lens and film or digital sensor. The film plane varies in distance from the lens focal point in each manufacturer. Thus each lens used has to be chosen carefully to assure that the image from the lens is focused on the exact place where the individual frame of film or digital sensor is positioned during exposure, the film plane is the location in which the lens creates the focused image which must be exactly upon the light-sensitive material. It is sometimes marked on a camera body with the 'Φ' symbol where the vertical bar represents the exact location.
Movie cameras often also have small focus hooks where the focus puller can attach one side of a tape measure to quickly gauge the distance to objects that he intends to bring into focus. The measurement is taken from the film plane to the subject.
Due to Petzval field curvature, the film plane upon which a lens focuses may not be a literal plane. Cameras may bend the film stock or even plate stock slightly to compensate, improving the area of critical focus and sharpness. Nevertheless, the general concept of a focal plane is understood to refer to this position in the camera sensor relative to the lens.
Famous quotes containing the words film and/or plane:
“All the old supports going, gone, this man reaches out a hand to steady himself on a ledge of rough brick that is warm in the sun: his hand feeds him messages of solidity, but his mind messages of destruction, for this breathing substance, made of earth, will be a dance of atoms, he knows it, his intelligence tells him so: there will soon be war, he is in the middle of war, where he stands will be a waste, mounds of rubble, and this solid earthy substance will be a film of dust on ruins.”
—Doris Lessing (b. 1919)
“As for the dispute about solitude and society, any comparison is impertinent. It is an idling down on the plane at the base of a mountain, instead of climbing steadily to its top.”
—Henry David Thoreau (1817–1862)