A photographing system according to one example embodiment includes a hardware photographing device configured to photograph each of a first pattern and a second pattern; at least one memory storing instructions; and at least one processor configured to execute the instructions to: set, for the hardware photographing device, a control value for changing the focal position; evaluate degrees of focus of a plurality of images of the first pattern and select an image having a maximum evaluation value, as well as evaluate degrees of focus of a plurality of images of the second pattern and select an image having a maximum evaluation value; and acquire a correspondence relationship between a focal position of an optical system and a control value, based on the control values used in capturing the images of the first pattern and the second pattern, and subject distances of the first pattern and the second pattern.