Variable Magnification Optical System Brightness Control
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Solution Overview
Problem
Conventional variable magnification optical systems face a significant reduction in lens brightness at the telephoto state due to their compact size, which compromises optical performance.
Innovation Solution
A variable magnification optical system comprising multiple lens groups with specific refractive powers and movements, including a vibration reduction lens group that adjusts orthogonally to the optical axis, to maintain image quality and brightness across zoom states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the entire lens system is configured with a relatively small size, then the back focus is shortened and the lens system is compact, but the lens brightness is extremely decreased in the telephoto state
Solution Approach 1:
The lens system is divided into multiple lens groups (first through fourth lens groups) with different refractive powers and movement characteristics. Each group can move independently during zooming, allowing optimized light path management that maintains brightness while keeping the overall system compact.
Solution Approach 2:
The patent implements dynamic movement of lens groups during zooming operations. The distances between lens groups are varied to achieve different focal lengths while maintaining optimal brightness characteristics. Additionally, a vibration reduction lens group can move orthogonally to the optical axis to correct image blur, providing adaptive performance across different shooting conditions.
2Length of stationary object
If the lens system is made compact with shortened back focus, then the overall size is reduced, but the brightness at telephoto state deteriorates significantly
Solution Approach 1:
The patent implements dynamic movement of lens groups during zooming operations. The distances between lens groups are varied to achieve different focal lengths while maintaining optimal brightness characteristics. Additionally, a vibration reduction lens group can move orthogonally to the optical axis to correct image blur, providing adaptive performance across different shooting conditions.
Solution Approach 2:
The patent optimizes specific parameter relationships, including focal lengths of different lens groups and their relative positions. By carefully controlling the ratio of focal lengths and movement distances, the system maintains sufficient brightness at telephoto state while achieving a compact form factor with shortened back focus.
3Adaptability or versatility
If zooming is implemented with multiple lens groups, then variable magnification is achieved, but the distances and positions become complex to control
Solution Approach 1:
The lens system is divided into multiple lens groups (first through fourth lens groups) with different refractive powers and movement characteristics. Each group can move independently during zooming, allowing optimized light path management that maintains brightness while keeping the overall system compact.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables a small-sized optical system with minimal aberration variation and sufficient brightness at the telephoto state, achieving high performance and efficient zooming capabilities.
Implementation Method 1
a lens group having negative refractive power within the 3b-th lens group being used as a vibration reduction lens group and moved so as to include a component in a direction orthogonal to the optical axis, whereby image plane correction is performed when image blurring occurs
Implementation Method 2
a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and a fourth lens group; upon zooming from a wide angle end state to a telephoto end state, a distance between the first lens group and the second lens group being varied
Data Source
AI summary
Provided is a variable magnification optical system comprising, in order from an object side along an optical axis, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, and a fourth lens group G4; upon zooming from a wide angle end state to a telephoto end state, a distance between the first lens group G1 and the second lens group G2 being varied, a distance between the second lens group G2 and the third lens group G3 being varied, and a distance between the third lens group and the fourth lens group being varied; the third lens group G3 comprising, in order from the object side along the optical axis, a 3a-th lens group G3a having positive refractive power, an aperture S, and a 3b-th lens group G3b having positive refractive power; a lens group having negative refractive power within the 3b-th lens group G3b being used as a vibration reduction lens group and moved so as to include a component in a direction orthogonal to the optical axis, whereby image plane correction is performed when image blurring occurs; and predetermined conditions being satisfied. Whereby, a small-size and high-performance variable magnification optical system, capable of realizing a small variation in aberration and attaining a sufficient brightness even in the telephoto state, an imaging apparatus, and a method for manufacturing the variable magnification optical system are provided.