Lens barrel

A lens barrel configured for detachably attaching to a camera body, comprising:

• a fixed tube section that has a base end for detachably attaching to the camera body, a top end, and a first pitch screw section formed on an inner peripheral surface of the top end;
• a movable tube section that is a tube member for holding a plurality of lenses and has a second pitch screw section formed at an outer peripheral surface, and is located so as to be movable inside the fixed tube section in such a state that the second pitch screw is threadedly engaged with the first pitch screw;
• a nut member threadedly engaged with the second pitch screw and abutting on the top end of the fixed tube section, so as to restrict a relative rotation between the fixed tube section and the movable tube section;
• wherein the plurality of lenses are two groups of lenses, a first group and a second group, held within the movable tube section;
• wherein the movable tube section has:
• a base movable tube section that has the second pitch screw and holding the first group of lenses;
• a top movable tube section detachably attached to the base movable tube section and holding the second group of lenses;
• and
• a first fixed diaphragm plate having a fixed diameter opening located between the base movable tube section and the top movable tube section and being located between the first and second groups of lenses;
• and
• one or more replacement fixed diaphragm plates having fixed diameter openings different from the fixed diameter opening of the first fixed diaphragm plate, the one or more replacement diaphragm plates configured for exchange with the first fixed diaphragm plate.