Variable Magnification Lens Group Configuration for Bright F-Value
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Solution Overview
Problem
There is a growing demand for a variable magnification optical system with satisfactory optical performance and a brighter F-value, which existing systems have not adequately addressed.
Innovation Solution
A variable magnification optical system is designed with a configuration that includes a first lens group with negative refractive power, a second lens group with positive refractive power, an intermediate group with negative refractive power, and a vibration-reduction lens group that is movable orthogonal to the optical axis. The system achieves varying magnification by adjusting the distances between these groups, ensuring the focal length ratios satisfy specific conditional expressions to maintain a bright F-value and correct aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a conventional variable magnification optical system with camera shake compensation is used, then the system provides basic imaging functionality, but the F-value is not bright enough and optical performance is insufficient
Solution Approach 1:
The optical system is divided into multiple lens groups with specific functions: first lens group (negative power) for wide-angle imaging, second lens group (positive power) for magnification control, intermediate group (negative power) for aberration correction, and vibration-reduction lens group for shake compensation. This segmentation allows each group to be optimized for its specific function, achieving both bright F-value and satisfactory optical performance
Solution Approach 2:
Each lens group is designed with specific refractive power characteristics and positional relationships to address local optical requirements. The intermediate group with negative refractive power is specifically positioned to correct aberrations, while the vibration-reduction lens group is configured to compensate for camera shake, ensuring local optimization of optical quality
2Adaptability or versatility
If the distance between lens groups is adjusted to achieve varying magnification, then the system provides flexible focal length adjustment, but aberrations such as spherical and coma aberrations occur
Solution Approach 1:
The system dynamically adjusts the distances between lens groups to achieve varying magnification from wide-angle to telephoto ends. The conditional expressions define the dynamic relationships between group distances and focal lengths, ensuring that aberration correction is maintained throughout the magnification range. The vibration-reduction lens group also provides dynamic adjustment to compensate for camera shake during operation
Solution Approach 2:
The system changes key parameters including the distances between lens groups, the refractive powers of individual groups, and the positional relationships defined by conditional expressions (1) and (2). These parameter changes allow the system to maintain satisfactory optical performance across different magnification states while providing flexible adaptability
3Illumination intensity
If the composite focal length ratio satisfies the conditional expression, then the system achieves a bright F-value, but the structural complexity increases
Solution Approach 1:
The intermediate group with negative refractive power serves multiple functions: it helps achieve the required composite focal length ratio for bright F-value, corrects aberrations, and maintains compact structural relationships. The vibration-reduction lens group also provides multi-functionality by enabling both shake compensation and contributing to the overall focal length control, reducing the need for additional dedicated components
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 a bright F-value of approximately F2.8 to F3.5 and effectively corrects aberrations such as spherical and coma aberrations, providing a wide angle of view and excellent imaging performance across various focal lengths.
Implementation Method 1
a first lens group having a negative refractive power
Implementation Method 2
a second lens group having a positive refractive power
Implementation Method 3
an intermediate group disposed closer to an image side than the second lens group... which has negative refractive power
Implementation Method 4
a vibration-reduction lens group disposed closer to the image side than the intermediate group and configured to be movable so as to have a component in a direction orthogonal to an optical axis
Data Source
AI summary
A variable magnification optical system comprises: a first lens group having a negative refractive power; at least one positive lens disposed closer to an image side than the first lens group; an aperture, the at least one positive lens being disposed between the first lens group and the aperture; an intermediate group having a plurality of lenses disposed closer to the image side than the aperture; and a vibration-reduction lens group disposed closer to the image side than the intermediate group. The plurality of lenses of the intermediate group integrally move upon varying magnification, and the system satisfies the conditional expression 1.500<f(1˜Gn)t/ft<100.000, where f(1˜Gn)t denotes a composite focal length from the first lens group to the intermediate group in a telephoto end state, and ft denotes a focal length of the entire system in the telephoto end state.