Zoom lens system, interchangeable lens apparatus and camera system

An interchangeable lens apparatus, comprising:

• a zoom lens;
• and
• a mount section connected to a camera body that includes an image sensor which receives an optical image formed by the zoom lens system thereby to convert the optical image to an electrical image signal, wherein
• the zoom lens system includes:
• an aperture diaphragm;
• a lens unit having negative optical power and being closest to the object side;
• a lens unit arranged on the object side relative to the aperture diaphragm and being adjacent to the aperture diaphragm, the lens unit that is arranged on the object side relative to the aperture diaphragm and is adjacent to the aperture diaphragm being arranged on the image side relative to the lens unit that is closest to the object side;
• and
• a lens unit arranged on the image side relative to the aperture diaphragm and being adjacent to the aperture diaphragm, wherein
• at the time of zooming, interval between the aperture diaphragm and the lens unit arranged on the object side relative to the aperture diaphragm and being adjacent to the aperture diaphragm varies, and interval between the aperture diaphragm and the lens unit arranged on the image side relative to the aperture diaphragm and being adjacent to the aperture diaphragm varies.

A camera system, comprising:

• an interchangeable lens apparatus that includes a zoom lens system;
• and
• a camera body which is connected to the interchangeable lens apparatus via a camera mount section in an attachable and removable manner and includes an image sensor which receives an optical image formed by the zoom lens system thereby to convert the optical image to an electrical image signal, wherein
• the zoom lens system includes:
• an aperture diaphragm;
• a lens unit having negative optical power and being closest to the object side;
• a lens unit arranged on the object side relative to the aperture diaphragm and being adjacent to the aperture diaphragm, the lens unit that is arranged on the object side relative to the aperture diaphragm and is adjacent to the aperture diaphragm being arranged on the image side relative to the lens unit that is closest to the object side;
• and
• a lens unit arranged on the image side relative to the aperture diaphragm and being adjacent to the aperture diaphragm, wherein
• at the time of zooming, interval between the aperture diaphragm and the lens unit arranged on the object side relative to the aperture diaphragm and being adjacent to the aperture diaphragm varies, and interval between the aperture diaphragm and the lens unit arranged on the image side relative to the aperture diaphragm and being adjacent to the aperture diaphragm varies.