Wide Angle Lens with Segmented Moving Group for Fast Focusing
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Solution Overview
Problem
Current wide angle lenses for cinematic applications face challenges in achieving a small F number for low-light imaging, a wide angle of view, and fast focusing speeds while minimizing the weight of lens groups that move during focusing operations, which are essential for high optical performance and efficient image capture.
Innovation Solution
A wide angle lens design comprising three lens groups: a fixed first lens group with positive refractive power, a moving second lens group with reduced weight, and a fixed third lens group, optimized with specific refractive power configurations and cemented lenses to achieve a small F number, wide angle of view, and reduced weight, while maintaining high optical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the entirety of lens groups positioned more toward the image side than the aperture stop are moved for focusing operations, then focusing functionality is achieved, but the weight of moving lens groups becomes heavy and focusing speed becomes slow
Solution Approach 1:
The lens system is divided into multiple lens groups (first through fourth lens groups) with different functions. Only the second lens group, which has relatively small weight, is moved for focusing operations, while the heavier first, third, and fourth lens groups remain fixed. This segmentation allows focusing functionality to be achieved with minimal moving mass, thereby improving focusing speed.
2Speed
If two lens groups are moved in different directions by different amounts for focusing operations, then focusing functionality is achieved, but the weights of moving lens groups must be further reduced to accelerate focusing speed
Solution Approach 1:
The focusing function is extracted and assigned to a single dedicated lens group (the second lens group) rather than requiring coordinated movement of multiple lens groups. This simplification reduces the complexity of the focusing mechanism while maintaining effective focusing capability, and allows the system to achieve fast focusing speeds with a single lightweight moving component.
3Reliability
If lens groups are configured to achieve wide angle of view and small F number, then optical performance is improved, but the weight of lens groups increases
Solution Approach 1:
Different lens groups are assigned specific optical functions with appropriate refractive powers. The second lens group, which is moved for focusing, is designed with optimized local optical properties (refractive power and position) to contribute to wide angle of view and small F number while maintaining minimal weight. The fixed lens groups handle other optical corrections, allowing the moving group to be lightweight yet effective.
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 design enables fast focusing speeds and high-quality, bright images with a wide angle of view, effectively addressing the limitations of existing lenses by optimizing lens configurations and refractive power distributions.
Implementation Method 1
a first lens group having a positive refractive power
Implementation Method 2
a second lens group that moves along the optical axis during focusing operations
Implementation Method 3
a cemented lens formed by cementing a lens having a positive refractive power and a lens having a negative refractive power together
Data Source
AI summary
A wide angle lens includes: a positive first lens group, a second lens group, constituted by two or fewer lenses, that moves during focusing operations, and a third lens group that includes at least one positive lens, provided in this order from the object side. The first lens group includes at least a positive meniscus lens with a convex surface toward the object side, a negative meniscus lens with a convex surface toward the object side, a lens having a concave surface with a radius of curvature having a smaller absolute value toward the image side, a negative lens, a cemented lens formed by a positive lens and a negative lens, and an aperture stop provided adjacent to the cemented lens toward the image side thereof, provided in this order from the object side. The wide angle lens satisfies a predetermined conditional formula.