A camera has a variable focal length lens and a viewfinder system whose magnification is variable in accordance with the focal length of the lens. A line array sensor generates an electrical signal in accordance with the intensity of the received light. A distance measuring optical system, which transmits light from a photographic object to the sensing elements of the sensor, has an optical axis which is different from the optical axis to the viewfinder system. A designator designates a particular sensing area, corresponding to the focal length of the lens, over the sensing elements of the sensor. A first distance data generator generates first distance data based on electrical signals generated by the sensing elements within the designated sensing area, and a second distance data generator generates second distance data based on electrical signals generated by the sensing elements outside of the designated sensing area. A discriminator discriminates whether the first distance data generator is operable. A selector selects the first distance data generator when it has been discriminated to be operable, and the second distance data generator when the first distance data generator is discriminated to be inoperable. A focusing device places the lens in an in-focus state based on the selected first or second distance data.