To provide an imaging apparatus etc. which solves a conventional problem of an imaging apparatus which is not capable of realizing a function to change the responsiveness of exposure control because it is not considered to change the responsiveness of an iris mounted to a lens side, from a camera side.

The imaging apparatus comprises: a camera unit 121 comprising imaging means 103; and a lens unit comprising diaphragm means 102. The imaging apparatus comprises: storage means 119 for storing diaphragm responsiveness information; selection means 110 for selecting the responsiveness of exposure control; generation means 110 for generating diaphragm responsiveness information from the responsiveness selected by the selection means and the diaphragm responsive information stored by the storage means; and control means 119 for controlling the responsiveness of the diaphragm means 102 on the basis of the diaphragm responsive information generated by the generation means.