An auto focus camera includes a usual zoom lens and provides a pseudo focal length mode, in which the size of focus condition detecting area, to the photographing scene to be printed, is variable. A pseudo focal length is stored and a focus condition is detected in accordance with a ray of light passed through the zoom lens. When the camera is in such a mode as to continuously detect focus condition for keeping an object in focus, or to be operated when the contrast of the object whose focus condition is detected is low, the focal length of the zoom lens and the pseudo focal length are controlled respectively in accordance with the mode.