Abstract: On a focus adjusting apparatus of an optical pickup apparatus, light reflected by a recording medium is concentrated into two focuses by an optical divider. First and second optical detectors are disposed so that a focus adjusting mechanism is controlled in accordance with the output of both detectors. Each optical detector includes central and peripheral light receiving planes. In a first system, the focus adjusting mechanism is controlled so that a difference of a ratio of a quantity of received light of the central light receiving plane to the whole quantity of received light of both the central and peripheral light receiving planes of the first optical detector and the same ratio of the second optical detector is reduced to O. Even if unblance occurs in the quantities of incident light to both the optical detectors, the unbalanced component is canceled between a denominator and a numerator of the above noted ratio.

Abstract: A camera including operable means changeable from an initial position to a predetermined position and vice versa, drive means for driving the operable means, detection means for detecting that the operable means reaches the predetermined position, control means for controlling the drive means, whereby the operable means is forcibly reset in the initial position when an erroneous operation occurs. The camera detects the occurrence of erroneous operations and automatically suspends the driving of the operable means so as to eliminate the influence of erroneous operations and assure accurate photography.