Zoom Lens Extender Layout for Long Focal Length Without Bulk
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Solution Overview
Problem
Existing zoom lenses with large aperture diameters and long focal lengths face challenges in maintaining good optical performance when an extender is inserted, often requiring large sizes and improper positioning, which complicates the integration of magnification conversion units.
Innovation Solution
A zoom lens design with specific refractive power relationships between lens units, allowing for an extender to be easily inserted while maintaining optical performance, comprising a first lens unit with positive power, a second with negative power, and a rear group with an n-th lens unit having positive power and an (n−1)-th lens unit with negative power, along with a detachable extender consisting of multiple cemented lenses to ensure proper magnification conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If an extender is inserted into the optical path to change focal length range, then the focal length can be extended to the long focal length side, but the overall lens length becomes large and the device size increases
Solution Approach 1:
The extender is designed to be detachably mounted within the lens barrel structure, nesting the extender optics inside the existing lens housing. This allows the focal length extension function to be added without proportionally increasing the overall lens length, as the extender components are integrated into the available internal space of the lens assembly.
Solution Approach 2:
The lens system employs variable air gaps between lens units that can be dynamically adjusted during zooming. By optimizing these air gaps according to specific inequalities involving focal lengths and distances, the system maintains good optical performance before and after extender insertion while avoiding excessive overall length increase.
2Ease of operation
If the position of extender insertion is not proper, then the main optical system and extender become large, but inserting at the correct position requires precise refractive power settings
Solution Approach 1:
The patent specifies precise parameter ranges for the refractive powers of lens units before and after the extender insertion point. By defining these parameters within specific inequalities ( involving focal lengths fn-1 and fn, and distances Lnm and Lsi), the system achieves optimal balance between ease of extender insertion and maintenance of good optical performance, reducing the need for complex trial-and-error configurations.
3Adaptability or versatility
If a large air gap is necessary to insert the extender, then the extender can be inserted, but the overall lens size becomes large
Solution Approach 1:
The lens system employs variable air gaps between lens units that can be dynamically adjusted during zooming. By optimizing these air gaps according to specific inequalities involving focal lengths and distances, the system maintains good optical performance before and after extender insertion while avoiding excessive overall length increase.
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 a zoom lens that can change focal length ranges easily, maintains good optical performance, and reduces overall size by optimizing the refractive power relationships and using a compact extender configuration.
Implementation Method 1
a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, and a rear group including a plurality of lens units
Data Source
AI summary
A zoom lens consists of, in order from an object side to an image side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, and a rear group including a plurality of lens units. A distance between adjacent lens units is changed during zooming. The rear group includes a diaphragm, an n-th lens unit disposed closest to an image plane and having a positive refractive power, and an (n−1)-th lens disposed on the object side of the n-th lens unit and having a negative refractive power. A predetermined condition is satisfied.