Abstract: An improved focus detecting apparatus comprises a photographic lens, a focus detecting device for detecting the focusing condition of the photographic lens and a lens driving means for driving the photographic lens based on the focusing condition detected, and the photographic lens is driven, in advance, to a focusing position where a frequently used magnification rate determined in accordance with the focal length of said photographic lens is attained, and then driven to an in-focus position.

Abstract: In an automatic focus control device of a camera there are provided defocus amount calculation means for calculating a defocus amount for a predetermined focus plane of a photographic lens in the camera on the basis of the electric signal generated by a light receiving means, comparing means for comparing the obtained value on the basis of the calculated defocus amount with a reference value, control means controlling driving speed of the photographic lens by the lens driving means in response to the comparison result of a comparing means, photographic condition setting means for setting the photographic condition and reference value setting means for setting said reference value in response to the set photographic condition.

Abstract: An auto-focus camera includes focus detection means for detecting the focussing state of a photographic lens, reliability discriminating means for discriminating whether the result of the focus detection means is reliable, first drive control means for driving the photographic lens to a position determined from the result of the focus detection means when the reliability discriminating means discriminates that the result is reliable, second drive control means for driving the photographic lens in a predetermined direction when the reliability discriminating means discriminates that the result is unreliable, and means for executing operations necessary for focussing during the predetermined direction driving, such as judgement as to whether a reverse driving is necessary, calculation of the driving amount of the photographic lens to an in-focus position.

Abstract: In an automatic focus detection device for use in a camera, a focus condition detecting unit detects a focus condition of a photographic lens in a camera based on the output of a light receiving device and calculates the amount of defocus of the photographic lens. An auxiliary light emitting device emits auxiliary light and comparator compares the stored output of memory and the output of the light receiving device under the ambient light; and then the detected defocus amount under the auxiliary light emission is corrected in accordance with the result of comparison so as to eliminate the bad effect of the color aberration of the lens of the camera, whereby a correct focus position can be detected.

Abstract: A camera with an automatic focusing device has an objective lens mounted on a camera. An image formed by the objective lens is divided into a plurality of zones. In each zone, a brightness distribution is obtained so as to detect a rough focusing condition in each zone, thereby producing a plurality of rough focusing condition data. Based on the result of the rough focusing condition data, one zone is selected. Furthermore, a precise focusing condition is detected in the selected zone based on the light contained in the selected zone, so as produce a precise focusing condition data. Based on the precise focusing condition data obtained from the selected zone, the object lens is driven to an infocus condition.

Abstract: In an automatic focus control device of a camera there are provided defocus amount calculation means for calculating a defocus amount for a predetermined focus plane of a photographic lens in the camera on the basis of the electric signal generated by a light receiving means, comparing means for comparing the obtained value on the basis of the calculated defocus amount with a reference value, control means controlling driving speed of the photographic lens by the lens driving means in response to the comparison result of a comparing means, photographic condition setting means for setting the photographic condition and reference value setting means for setting said reference value in response to the set photographic condition.

Abstract: A focus detection condition display device suitable for use in a camera provided with an electronic viewfinder. The pattern signal corresponding to a focus detection zone on which focus detection is conducted by a focus detecting system is superimposed on the video signal of the object field and said signal is output to an electronic viewfinder. When the focus detection has become impracticable for such reason as lack of contrast of the object field, or focusing has become impracticable because of the object coming too close to the camera, an alarm is issued by the pattern corresponding to a focus detection zone displayed on the electronic viewfinder displaying in a manner different from that ordinarily used.

Abstract: An automatic focus control device for use in a camera in which a defocus condition of the lens of the camera is detected by estimating the defocus value by detecting the motion of the photographic object.

Abstract: In an automatic focus detection device for use in a camera, a focus condition detecting unit detects a focus condition of a photographic lens in a camera based on the output of a light receiving device and calculates the amount of defocus of the photographic lens. An auxiliary light emitting device emits auxiliary light and comparator compares the stored output of memory and the output of the light receiving device under the ambient light; and then the detected defocus amount under the auxiliary light emission is corrected in accordance with the result of comparison so as to eliminate the bad effect of the color aberration of the lens of the camera, whereby a correct focus position can be detected.