(under subclass 257) Subject matter in which the diaphragm is adjusted to obtain a specific aperture size by an engagement of a mechanical device allowing rotation in only one direction (i.e., a pawl) with a toothed wheel (i.e., a ratchet).
SEE OR SEARCH THIS CLASS, SUBCLASS:
, FOR 748, for a foreign art collection involving camera automatic exposure control having a ratchet/pawl mechanism for controlling diaphragm only.
