A detecting device compares, with a threshold value, a difference or ratio between values of information on distances or defocused states of two distributed points in a distribution of distances or defocused states in an object space and determines whether two areas corresponding to the two distributed points represent one and the same object according to the result of comparison. The detecting device sets the threshold value at a value based on the information on distances or defocused states of the two distributed points subjected to determination, so that fluctuations of the determination taking place depending on distances or defocused states can be lessened.
Distance detecting device, focus state detecting device and camera having same