Variable-magnification observation optics

Abstract

These variable-magnification observation optics are provided with an objective system, an erecting system, and an eyepiece system. In order from the object side, the objective system comprises a positive first group, a positive second group, and a negative third group. In order from the object side, the eyepiece system comprises a positive fourth group and a positive fifth group. The erecting system is located between the first and second groups. In order from the object side, the fifth group comprises a negative meniscus lens, the concave surface of which faces the object side, and a positive lens, with an air gap therebetween. The fifth group has at least one aspheric surface.

Description

technical field [0001] The present invention relates to a variable magnification observation optical system, for example, relates to a variable magnification observation optical system used in medical magnifiers, work magnifiers, binoculars, ground telescopes and the like. Background technique [0002] In observation optical systems used in magnifying glasses, binoculars, ground telescopes, etc., conventionally, a reverse erecting system such as a prism is used to invert the inverted image formed by the objective lens system into an erected image, and observe the image through the eyepiece system. The so-called Keplerian type (real image type) of the type. In addition, a zoom optical system having a zoom ratio of about 2x is easy to downsize, so as proposed in Patent Document 1, a zoom type that performs zooming with a pair of lenses sandwiching the above-mentioned inverted image is generally employed. [0003] For example, in Example 1 of Patent Document 1, for the purpose...

AI Technical Summary

Problems solved by technology

[0005] In Embodiment 1 of Patent Document 1, the moving group is composed of a plurality of lenses, so the weight of the moving group increases and the mechanical structure becomes complicated

Therefore, it is difficult to reduce the weight of the whole unit

In Example 2 of Patent Document 1, the group closest to the pupil in the eyepiece system is composed of only a pair of cemented lenses, so it is difficult to simultaneously and satisfactorily correct aberrations in the central portion and the peripheral portion

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