Variable magnification optical system, optical apparatus, and method for producing variable magnification optical system
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Solution Overview
Problem
Conventional variable magnification optical systems fail to adequately suppress variations in aberrations upon focusing, particularly in photographic and electronic cameras.
Innovation Solution
A variable magnification optical system comprising multiple lens groups with specific focal length and back focus ratios, where the object side focusing lens group moves differently from the image side focusing lens group during focusing, adhering to conditional expressions to control aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional variable magnification optical systems are used, then the system structure is simple, but variations in aberrations upon focusing cannot be adequately suppressed
Solution Approach 1:
The optical system divides focusing functions into separate lens groups: object side focusing lens groups and image side focusing lens groups. Each group handles focusing independently with different movement trajectories, allowing aberration suppression without requiring complete redesign of the entire optical system.
Solution Approach 2:
The patent implements dynamic focusing by allowing lens groups to move along different trajectories during focusing operations. The object side focusing lens groups and image side focusing lens groups have distinct movement paths, enabling adaptive correction of aberrations across varying magnification states.
2Reliability
If multiple focusing lens groups with different trajectories are introduced, then aberration variations are suppressed, but the device complexity increases
Solution Approach 1:
Different lens groups are assigned specific roles: object side focusing lens groups (with focal lengths satisfying 0.30 < fF1 < 0.80 times the wide-angle focal length) and image side focusing lens groups (with focal lengths satisfying 0.15 < fF2 < 0.50 times the wide-angle focal length). Each group has optimized local properties for its specific focusing function.
Solution Approach 2:
The patent optimizes specific parameters including the ratio of focal lengths between object side and image side focusing lens groups, back focus distance (0.10 < BFw/fw < 0.50), and movement trajectories. These parameter changes enable effective aberration suppression while controlling system complexity.
3Manufacturing precision
If the back focus is optimized for wide angle end state, then imaging performance is improved, but the system becomes less adaptable to other magnification states
Solution Approach 1:
The optical system design with multiple focusing lens groups and optimized parameter ranges enables the system to maintain good imaging performance across multiple magnification states (wide-angle, intermediate, and telephoto ends). The back focus and focal length ratios are set to achieve universal adaptability rather than optimization for a single state.
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 system effectively corrects spherical and coma aberrations across varying magnification states, ensuring high-quality imaging performance from infinity to close distances.
Implementation Method 1
a variable magnification optical system comprising a plurality of lens groups; upon varying a magnification, distances between respective lens groups in said plurality of lens groups being varied
Data Source
AI summary
A variable magnification optical system comprising a plurality of lens groups and, upon varying a magnification, distances between respective lens groups in the plurality of lens groups being varied. The plurality of lens groups comprises an object side focusing lens group which is moved upon carrying out focusing and at least one image side focusing lens group disposed in a more image side than the object side focusing lens group and moved with a trajectory differing from that of the object side focusing lens group, upon carrying out focusing. The predetermined conditional expressions are satisfied. Thus, variations in aberrations upon varying magnification from the wide angle end state to the telephoto end state as well as variations in aberrations upon carrying out focusing from an infinite distance object to a close distance object can be suppressed superbly.