PURPOSE: To eliminate the effect of variations in the outputs among photoelectric transducer groups and sliminate the need for driving circuits by processing the respective outputs of two groups of the photoelectrlic transducers which change the changes in the respective relative positions of the subject to electric signals by an electrical processing unit.
CONSTITUTION: While the subject 1 is projected through total reflecting mirrors 2, 4 onto a photoelectric transducer group 8 by a projecting lens 6, it is projected through total reflecting mirrors 3 (rotary type), 5 onto a photoelectric transducer group 9 by a projecting lens 7. The outputs i1..., i1'... proportional to the quantity of incident light from the respective photoelectric transducers d1..., d1' are led to an electric processing circuit 10, whereby the focuses are detected and measured. in the processing circuit 10, the effect of variations in the outputs is removed by obtaining the output differences between the adjoining transducers of the same group of two sets of the transducer groups and the time when focus matches is detected by converting the output differences to absolute values, again obtaining differences between the diagonal ones among the transducers, doing so between the diasonal ones in the opposite direction, obtaining the differences therebetween, converting front focus, rear focus and focusing and ditecting the ration at which said output differences become zero.
SADANAO MASAO
NAKAMURA KAZUO
