Zoom Lens with Stationary Groups for Large Image Circle
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Solution Overview
Problem
Existing zoom lenses with a five-group system suffer from large lateral chromatic aberration and a small image circle, making them unsuitable for modern cameras with larger sensors that require high image quality and larger image circles, while also needing to maintain a compact size.
Innovation Solution
A zoom lens configuration with a first lens group having positive refractive power, a second lens group with negative refractive power, a third lens group with positive refractive power, and a fifth lens group with positive refractive power, where the first and fifth lens groups remain stationary during zooming, and the second and third lens groups move along the optical axis, with specific lens group configurations and cemented lenses to control aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the five-group lens system is proportionally enlarged to increase the image circle size, then the image circle becomes large enough for modern cameras, but the overall length of the lens system becomes long
Solution Approach 1:
The lens system is divided into five distinct lens groups (G1-G5) with different refractive powers and movement characteristics. During zooming, only G2, G3, and G4 move while G1 and G5 remain stationary, segmenting the zooming function to control overall length while maintaining image circle size
Solution Approach 2:
The lens groups are configured with dynamic movement characteristics during zooming - G2 moves to the image side, G3 and G4 change distances with adjacent groups, while G1 and G5 remain stationary. This dynamic configuration allows the system to maintain a compact overall length while achieving a large image circle
2Reliability
If the five-group lens system is proportionally enlarged to achieve favorable optical performance, then optical quality improves, but the lateral chromatic aberration increases and image circle remains small
Solution Approach 1:
Each lens group is assigned specific local optical characteristics - G1 has positive power with stationary positioning, G2 has negative power and moves during zooming, G3-G5 have positive power with varying movement. The second lens group specifically uses one positive lens and one or more negative lenses with controlled Abbe numbers to address chromatic aberration locally while maintaining overall optical performance
3Reliability
If larger sensor size is used to obtain high image quality, then image quality improves, but the lens system requires larger image circle which increases system size
Solution Approach 1:
The lens system segments zooming and focusing functions across five groups, with G1 and G5 stationary during zooming to define the overall size envelope, while G2-G4 handle zooming movements internally. This segmentation allows achieving large image circle for high image quality while controlling external dimensions
Solution Approach 2:
The patent addresses the size issue by optimizing the arrangement and movement characteristics of lens groups along the optical axis, utilizing the dimensional space efficiently. The stationary G1 and G5 groups establish boundaries while moving groups operate within this fixed envelope, achieving large image circle without proportional increase in overall length
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 provides a zoom lens with a large image circle and favorable optical performance while maintaining a compact size, effectively reducing chromatic aberrations and spherical aberrations, and allowing for high image quality across various zoom settings.
Implementation Method 1
a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, a third lens group G3 having a positive refractive power, a fourth lens group G4 having a positive refractive power, and a fifth lens group G5 having a positive refractive power
Data Source
AI summary
The zoom lens consists of, in order from an object side, a positive first lens group, a negative second lens group, a positive third lens group, a positive fourth lens group, and a positive fifth lens group. During zooming, the second lens group, the third lens group, and the fourth lens group move. The first lens group consists of, in order from an object side, a negative first a lens group, a positive first b lens group that moves during focusing, and a positive first c lens group. The second lens group includes one positive lens and one or more negative lenses successively in order from a most object side to an image side.