Variable-focal-length lens system and imaging apparatus

Abstract

The invention provides a variable-focal-length lens system and an imaging apparatus. The variable-focal-length lens system includes first to fifth lens groups having positive, negative, positive, negative, and positive refractive powers, respectively, from the object side. As the lens-position state changes from wide-angle to telephoto, the air space between the first and second lens groups increases, the air space between the second and third lens groups decreases, the air space between the third and fourth lens groups changes, the air space between the fourth and fifth lens groups increases, the first lens group moves monotonously toward the object, the second lens group is fixed in the optical-axis direction, and the third and fourth lens groups move toward the object. Conditions 0.2<D23w / ft<0.4, 0.1<f2 / f4<0.4 are satisfied, D23w, ft, and f2 and f4 being the air space between the second and third lens groups at wide-angle, lens system's overall focal length at telephoto end, and focal lengths of the second and fourth lens groups, respectively.

Description

[0001] References to related applications [0002] The present application contains subject matter related to that disclosed in Japanese Priority Patent Application JP 2009-046783 filed in the Japan Patent Office on Feb. 27, 2009, the entire content of which is hereby incorporated by reference. technical field [0003] The present invention relates to a variable focal length lens system and an imaging device. More specifically, the present invention relates to a variable focal length lens system used for a digital video camera, digital still camera, etc. and having a zoom ratio greater than 5 times, and an imaging device using the variable focal length lens system. Background technique [0004] In the prior art, in order to perform recording in a digital camera, there is a method in which a photoelectric converter such as a CCD (Charge Coupled Device) sensor or a CMOS (Complementary Metal Oxide Semiconductor) sensor is used by an imaging device to be formed in the imaging de...

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Problems solved by technology

[0009] This is because when the position of the exit pupil of the lens system becomes closer to the photoelectric converter, that is, when the angle formed between the chief ray reaching each photoelectric converter and the optical axis becomes larger, toward the periphery of the picture plane The off-axis beam in the direction forms a large angle with the optical axis, and the off-axis beam does not reach the photoelectric converter, resulting in insufficient light

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