A finder apparatus which is used together with a photographing apparatus presents
a marker for positioning for setting relative positions of the photographing apparatus
and an object for calibration so as to be visually recognizable by an operator
in a finder configured to present an image of a subject so as to be visually recognizable
by the operator, when photographing the object for calibration including at least
one of a known shape and a known surface attribute in order to acquire parameters
of a photographing optical system of the photographing apparatus.
