Compact Zoom Lens Design for Cinematic Imaging
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Solution Overview
Problem
There is a lack of compact, lightweight, and high-performance wide angle zoom lenses compatible with the increasing pixel density of cinematic cameras, which are essential for varied imaging styles and demand for portable lenses.
Innovation Solution
A zoom lens configuration comprising a fixed positive refractive power first lens group, independently movable lens groups, and a final fixed positive refractive power lens group, optimized by specific refractive index and focal length conditions to achieve a wide angle of view while minimizing size and weight, with aspherical surfaces and cemented lenses for improved aberration correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If conventional wide angle zoom lens configurations are used, then image size coverage is adequate, but lens size and weight are excessive
Solution Approach 1:
The lens is divided into multiple lens groups (first lens group with positive refractive power, second lens group with negative refractive power, third lens group with positive refractive power) that can move independently. This segmentation allows each group to contribute differently to the overall optical function, enabling miniaturization while maintaining wide angle of view and multiple image size capabilities
Solution Approach 2:
The second lens group is configured to move along the optical axis during zooming operations, and the third lens group moves during focusing operations. This dynamic configuration allows the lens to achieve variable magnification and focus adjustment in a compact form factor, resolving the contradiction between small size and versatile image size coverage
2Volume of moving object
If lens groups are made smaller to reduce overall lens size, then portability improves, but aberration correction becomes more difficult
Solution Approach 1:
Aspherical surfaces are introduced in specific lens elements (first lens group and second lens group) to locally correct spherical aberration and other off-axis aberrations. This localized application of advanced optical surfaces enables effective aberration correction without increasing overall lens volume, as the correction is achieved at critical locations rather than throughout the entire optical system
Solution Approach 2:
Cemented lens structures are employed where lens elements with different refractive indices and Abbe numbers are bonded together. This composite approach allows simultaneous correction of spherical aberration, coma, and chromatic aberration within compact lens groups, achieving high manufacturing precision without increasing lens volume
3Reliability
If more lens groups are added to improve image quality, then performance increases, but device complexity increases
Solution Approach 1:
The third lens group serves multiple functions: it acts as a focusing lens group that moves along the optical axis for focus adjustment, and simultaneously contributes to correcting spherical aberration and coma through its aspherical surface. This multi-functionality reduces the need for separate dedicated correction elements, thereby reducing overall device complexity while maintaining high image quality
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 the design of compact, lightweight zoom lenses with a wide angle of view and high image quality, suitable for cinematic cameras, by adhering to specific refractive index and focal length conditions, and incorporating aspherical surfaces and cemented lenses for effective aberration correction.
Implementation Method 1
a first lens group having a positive refractive power which is fixed while changing magnification; two or more movable lens groups that move independently from each other while changing magnification; and a final lens group having a positive refractive power which is fixed while changing magnification
Data Source
AI summary
A zoom lens includes: a first lens group having a positive refractive power which is fixed while changing magnification; two or more movable lens groups that move independently from each other while changing magnification; and a final lens group having a positive refractive power which is fixed while changing magnification, provided in this order from an object side. The zoom lens satisfying Conditional Formula (1) below:1.30<h/(Yimg·tan θ)<2.37 (1).