Zooming lens and camera device

Abstract

The invention provides a zooming lens, which is small-sized and has good optical performance, and has little performance deterioration of the manufacture error or the assembly error even the focal power of a second lens group. The zooming lens, from the objective side, has, in order, a positive first lens group (G1), a negative second lens group (G2) moving to zoom, a diaphragm, a positive third lens group (G3), and a positive fourth lens group (G4) for performing the correction and focusing of the image position with the zooming. The second lens group (G2), from the objective side, has, in order, a first negative lens (L21), a curved moon-shaped lens (L22) with a convex surface toward the objective side, a second negative lens (L23), and a positive lens (L24). The focal length of the curved moon-shaped lens (L22) is f22, the focal length of the second lens (G2) is f2, thus the formula (1) is satisfied: the absolute value of f22 / f2 is more than 5.0 (1).

Description

technical field [0001] The present invention relates to a zoom lens and an imaging device, and more particularly relates to a zoom lens suitably used for a video camera, an electronic still camera, a surveillance camera, etc., and an imaging device including the zoom lens. Background technique [0002] Conventionally, 4-group or 5-group zoom lenses have been proposed as zoom lenses for consumer video cameras, surveillance video cameras, and the like. For example, Patent Documents 1 and 2 disclose a zoom lens having a zoom ratio of about 10 times and an F-number of about 1.8. In this type, no matter it is a single-plate type or a 3-plate type, most of the zoom lenses commonly use the first lens group composed of negative lens, positive lens, and positive lens, and the negative lens, negative lens, etc. , The structure of the second lens group composed of three positive lenses. [0003] Patent Document 1: Japanese Patent Laid-Open No. 2006-221208 [0004] Patent Document 2:...

AI Technical Summary

Problems solved by technology

[0005] However, in the above-mentioned zoom lens, in order to reduce the amount of movement of the second lens group accompanying the magnification change and to reduce the size of the optical system, a large negative refractive power is often given to the second lens group, so each The focal power of the lens becomes larger

In this case, there is a problem that performance degradation due to manufacturing errors or assembly errors tends to be large

Images