Variable Magnification Optical System High-Speed Focusing
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Solution Overview
Problem
Existing variable magnification optical systems are not optimized for reducing the weight of the focusing group sufficiently and are not suitable for high-speed focusing operations.
Innovation Solution
A variable magnification optical system comprising a first lens group with positive refractive power, an intermediate group with negative refractive power, a focusing group with positive refractive power that moves upon focusing, and an image side group with positive refractive power, where the distances between these groups are varied to achieve magnification changes, and the image side group is composed of an A group, a B group with negative refractive power satisfying a specific focal length ratio, and a C group, allowing for effective vibration reduction and correction of aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the focusing group is made lighter to enable high-speed focusing, then focusing speed is improved, but optical performance and aberration correction may deteriorate
Solution Approach 1:
The image-side group is segmented into three sub-groups (A, B, and C) with different refractive powers. The B group with negative refractive power is specifically designed to correct aberrations, allowing the focusing group to be lighter while maintaining optical performance through the coordinated action of these segmented components.
Solution Approach 2:
The B group with negative refractive power acts as an intermediary element between the A and C groups. This intermediate group with negative power helps correct aberrations introduced by the positive power groups, enabling the focusing group to achieve high-speed operation while maintaining reliable optical performance.
2Object-affected harmful factors
If the image side group is designed with specific focal length ratios for vibration reduction, then camera shake correction is improved, but device complexity increases
Solution Approach 1:
The patent specifies particular focal length ratios (1.67 ≤ -fA/fB and 2.33 ≤ -fB/fC) as key parameters to achieve vibration reduction. By optimizing these numerical parameters, the system reduces camera shake impact without requiring complex mechanical stabilization mechanisms, thus balancing performance improvement with controlled complexity.
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 achieves excellent optical performance, reduces the weight and size of the focusing lens group, enabling high-speed focusing operations while effectively correcting various aberrations and minimizing the impact of camera shake.
Implementation Method 1
a first lens group disposed at a most object side and having positive refractive power, an intermediate group disposed at an image side of the first lens group and having negative refractive power, a focusing group disposed at an image side of the intermediate group and having positive refractive power
Data Source
AI summary
A variable magnification optical system includes a positive first lens group disposed at a most object side, a negative intermediate group disposed at an image side of the first lens group, a positive focusing group disposed at an image side of the intermediate group, and a positive image side group disposed at an image side of the focusing group. Upon varying magnification, a distance between the first lens group and the intermediate group, a distance between the intermediate group and the focusing group and a distance between the focusing group and the image side group are varied; and the image side group includes, in order from an object side, a positive A group, a negative B group satisfying a predetermined conditional expression with respect to the A group, and a C group, whereby excellent optical performance, high speed focusing, and other advantages are achieved.