Zoom lens system and image capture apparatus having the same

Abstract

A zoom lens system has four lens units, i.e., in order from an object side to an image side, a first lens unit of negative optical power, a second lens unit of positive optical power, a third lens unit of positive optical power, and a fourth lens unit of positive optical power. During zooming from a wide-angle end to a telephoto end, a space between the first lens unit and the second lens unit decreases, a space between the second lens unit and the third lens unit varies, and a space between the third lens unit and the fourth lens unit increases. Two negative lens elements constituting the first lens unit are made from high refractive index materials. Accordingly, a small-sized zoom lens system capable of obtaining a desired wide angle of field at the wide-angle end, a desired zoom ratio and high optical performance with a minimum number of lens elements can be provided.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to zoom lens systems which are suitable, for example, for use as a photographing optical system for digital still cameras. [0003] 2. Description of the Related Art [0004] Digital still cameras for capturing still images using a solid-state image sensor, such as a CCD (charge-coupled device) sensor or a CMOS (complementary metal oxide semiconductor) sensor, have received attention in recent years. It is desirable to have such digital still cameras small and compact in size. Accordingly, it is desirable for a photographing optical system serving as one of the units of a digital still camera to be very short in total length. [0005] In addition, it is desirable for the photographing optical system to have a wide angle of field in consideration of capturing still images. Moreover, it is desirable for the photographing optical system to provide high optical performance since the digital still...

AI Technical Summary

Benefits of technology

[0017] The present invention is directed to a small-sized zoom lens system capable of obtaining a desired wide angle of

Problems solved by technology

However, the zoom lens disclosed in Japanese Patent Publication No. 6-66008 has a great number of lens elements and is, therefore, disadvantageous in terms of compactness.

Therefore, although the zoom lens can be used as a photographing optical system of a silver-halide film camera without problems, the size of the zoom lens tends to increase because design limitations are imposed on power arrangement wh

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