Zoom lens system, interchangeable lens apparatus and camera system

#This application is based on Japanese Patent Application Nos. 2009-021832 and 2009-021833 filed on Feb. 2, 2009. Hereby, the contents of Japanese Patent Application Nos. 2009-021832 and 2009-021833 are incorporated by reference.

#1. Field of the Invention

#The present invention relates to a zoom lens system and, in particular, to a zoom lens system suitable for an imaging lens system employed in an interchangeable lens apparatus in a so-called interchangeable-lens type digital camera system. Further, the present invention relates to an interchangeable lens apparatus and a camera system that employ this zoom lens system.

#FIG. 1 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment 1 (Example 1);

#FIG. 2 is a longitudinal aberration diagram showing an infinity in-focus condition of a zoom lens system according to Example 1;

#FIG. 3 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment 2 (Example 2);

#FIGS. 1, 3, 5, 7, 9, 11, 13 and 15 show lens arrangement diagrams of zoom lens systems according to Embodiments 1, 2, 3, 4, 5, 6, 7 and 8, respectively, and each show a zoom lens system in a infinity in-focus condition.

#In each diagram, part (a) shows a lens configuration at a wide-angle limit (in the minimum focal length condition: focal length fW), part (b) shows a lens configuration at a middle position (in an intermediate focal length condition: focal length fM=√{square root over ( )}(fW*fT)), and part (c) shows a lens configuration at a telephoto limit (in the maximum focal length condition: focal length fT). Further, in each diagram, each bend arrow located between part (a) and part (b) indicates a line obtained by connecting the positions of the lens units respectively at a wide-angle limit, a middle position, and a telephoto limit, in order from the top. In the part between the wide-angle limit and the middle position, and the part between the middle position and the telephoto limit, the positions are connected simply with a straight line, and hence this line does not indicate actual motion of each lens unit. Moreover, in each diagram, an arrow imparted to a lens unit indicates focusing from an infinity in-focus condition to a close-object in-focus condition. That is, the arrow indicates the moving direction at the time of focusing from an infinity in-focus condition to a close-object in-focus condition.

#In FIGS. 1, 3, 5, 7, 9, 11, 13, and 15, asterisk “*” imparted to a particular surface indicates that the surface is aspheric. Further, in each diagram, symbol (+) or symbol (−) imparted to the symbol of each lens unit corresponds to the sign of the optical power of the lens unit. Still further, in each diagram, the straight line located on the most right-hand side indicates the position of the image surface S. Still further, in each diagram, the straight line located between adjoining lens elements indicates the position of an aperture diaphragm A.