Inner zoom lens

Abstract

The invention discloses an inner zoom lens, which comprises a first lens group with a positive refractive index, a second lens group with a negative refractive index, a third lens group with a positive refractive index, and a fourth lens group with a positive refractive index in sequence on an optical axis from an object to an image, wherein the first lens group for receiving light is fixed. When a focal distance of the inner zoom lens changes from a wide angle end to a telephoto end, the second lens group moves towards the image, and the third lens group moves towards the object in order to increase spacing between the first and the second lens groups and shorten spacing between the second and the third lens groups. The fourth lens group moves in the process of focusing, can function as a compensation system in the process of zooming, and moves independently to perform a focusing action after moving together with the second and third lens groups simultaneously to perform a zooming action in order to compensate the movement of an imaging surface caused by zooming. The inner zoom lens disclosed by the invention has the characteristics of high optical zoom and large aperture, and can meet the requirements of short optical total length, good imaging performance, low manufacture cost and the like.

Description

technical field [0001] The invention relates to a zoom lens, in particular to an internal zoom lens with a high zoom ratio and a large aperture applied to a camera or image-taking device. Background technique [0002] An external zoom or sunken zoom lens is a retractable lens that stretches out to the outside of the fuselage when zooming. Most of the digital cameras currently on the market use this kind of sunken lens. In order to achieve a thin structure, the sunken lens generally adopts a three-group lens group structure with negative, positive and positive refractive powers, and then zooms in a way that one group (such as the first group) retracts. However, under this structure, in order to achieve a high zoom ratio, the moving distance of the lens zoom must be relatively large, so it is still unable to effectively achieve the purpose of thinning. In addition, because this kind of sunken lens, especially the lens with high zoom ratio, has to extend out of the fuselage f...

AI Technical Summary

Problems solved by technology

In addition to the characteristics of total optical length and large aperture, monitor lenses are also increasingly required to have a high zoom ratio (Zoom Ratio), such as a 10x zoom ratio, which is suitable for telephoto shooting because it can shoot clearly distant scenes. Therefore, the difficulty of its design is further increased

[0005] Usually, the internal zoom lens with high zoom ratio is implemented with multiple lens groups, multiple lenses, and a long lens length, which does not meet the current trend of miniaturization and thinning of electronic devices.

At the same time, in order to correct various aberrations such as lateral chromatic aberration caused by the increase of zoom ratio, these internal zoom lenses have added a number of special low dispersion (LD, Low Dispersion) lenses and aspheric lenses to meet the requirements of high resolution. Adding multiple expensive special low dispersion lenses will significantly increase the manufacturing cost

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