An apparatus for calculating correlation between first and second sets of data which are respectively composed of plural data includes a first transfer apparatus, a second transfer apparatus, and an apparatus for calculating absolute value. The first transfer apparatus comprises at least first and second transfer stages and is adapted to transfer the first set of data in succession from the first transfer stage to the second transfer stage, and the second transfer apparatus comprises at least first and second transfer stages and is adapted to transfer the second set of data in succession from the second transfer stage to the first transfer stage in synchronization with the data transfer by the first transfer apparatus. The absolute value to be calculated is that of the difference between the data in the first transfer stage of the first transfer apparatus and the data in the first transfer stage of the second transfer apparatus in synchronization with the data transfer by the first and second transfer apparatuses.
A focus state detecting device for a camera has plural areas for focus state detection for an object, and is capable of securing wide focus state detecting areas. The device has a pair of first photo-detector arrays arranged in a first direction and a pair of second photo-detector arrays arranged in a second direction, wherein the light receiving area of the first arrays is wider than that of the second arrays, and the first direction is the same as the longitudinal direction of the photographing field.
