Zoom lens and image pickup apparatus including the same

Abstract

The invention relates to a zoom lens and an image pickup apparatus including the same. The zoom lens includes first to fourth lens units in order from the object side to the image side. The first, third, and fourth lens units have a positive refractive power. The second lens unit has a negative refractive power. During zooming from a wide-angle end to a telephoto end, the first lens unit moves along a locus convex toward the image side, the second lens unit moves along a locus convex toward the image side from the wide-angle end to an intermediate zoom position and along a locus convex toward the object side from the intermediate zoom position to the telephoto end, and the third lens unit moves such that the distance to the second lens unit at the telephoto end is smaller than that at the wide-angle end. Focal lengths of the first lens unit and the entire lens system at the telephoto end are adequately set.

Description

technical field [0001] The present invention relates to a zoom lens and an image pickup device including the zoom lens. The present invention is applicable to, for example, an image pickup device such as a video camera including a solid-state image pickup element, an electronic still camera, a broadcast camera or a surveillance camera, or a silver halide film camera. Background technique [0002] Recently, image pickup devices have become smaller with increased functionality. Accordingly, demand for small, high zoom ratio (high magnification change ratio) zoom lenses with short length and high resolution for imaging optical systems of image pickup devices has increased. [0003] In order to comply with this demand, post-focus zoom lenses have been proposed that perform focusing by moving lens units other than the first lens unit disposed on the object side. [0004] In the post-focus zoom lens, the effective diameter of the first lens unit is generally small compared to th...

AI Technical Summary

Problems solved by technology

[0012] However, as the refractive power of each lens surface increases, the lens thickness increases, and the length of the lens system cannot be sufficiently reduced

Also, it becomes difficult to correct aberrations such as chromatic aberration at the telephoto end

[0013] In addition, as the zoom ratio increases, the influence of assembly errors (such as the tilt of each lens or lens unit) increases

[0014] If the sensitivity to the eccentricity of each lens or lens unit is high, the optical performance is greatly degraded due to the eccentricity due to assembly errors

As a result, the optical performance is also greatly degraded in the vibration-reduced state

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