Zoom Lens with Fixed Outer Groups for High Magnification

The zoom lens is divided into five distinct lens groups (G1-G5) with specific refractive powers, where each group performs a specialized function. The first lens group (G1) with positive refractive power handles initial light convergence, the second lens group (G2) with negative refractive power provides divergence, and the third through fifth lens groups (G3-G5) with positive refractive power complete the focusing. This segmentation allows high magnification to be achieved through coordinated movement of these specialized groups rather than using a single complex group.

The patent implements dynamic movement of the second, third, and fourth lens groups (G2-G4) along the optical axis during zooming operations, while the first and fifth lens groups (G1 and G5) remain fixed. This dynamic configuration allows the intervals between adjacent lens groups to change continuously, enabling high magnification ratios without requiring all lens groups to be large or complex. The selective movement optimizes the optical path for different focal lengths.

The zoom lens divides the zooming function across three movable lens groups (G2, G3, G4) rather than using a single complex moving assembly. Each group contributes to the overall zoom range through its specific movement pattern, allowing the system to achieve versatile focal length adjustment while keeping individual group movements relatively simple and compact.

The patent employs dynamic movement of lens groups G2, G3, and G4 along the optical axis during zooming, with all intervals between adjacent lens groups changing simultaneously. This coordinated dynamic adjustment enables a wide zoom range to be achieved through relatively compact mechanical structures, as the movement is distributed across multiple groups rather than requiring a single large-travel mechanism.

The optical power is segmented across five lens groups (G1-G5) with alternating positive and negative refractive powers. The first lens group (G1) has positive refractive power for initial convergence, the second lens group (G2) has negative refractive power for divergence and aberration correction, and the third through fifth lens groups (G3-G5) have positive refractive power for final focusing. This segmentation distributes the refractive power requirement across multiple smaller groups, maintaining compact lens size while achieving excellent optical characteristics through the combined effect of all groups.

Each lens group is assigned a specific local function: G1 provides initial convergence, G2 provides divergence and corrects certain aberrations, G3-G5 provide final focusing and correct other aberrations. The second lens group (G2) with negative refractive power is specifically positioned to correct spherical and chromatic aberrations introduced by the positive power groups. This local specialization of optical quality in each group allows compact sizing while maintaining overall optical excellence.

The zoom lens segments the zooming function by fixing only the first (G1) and fifth (G5) lens groups while allowing the intermediate groups (G2, G3, G4) to move. This segmentation of fixed and movable elements achieves high magnification ratios through the coordinated movement of the three intermediate groups, while keeping the overall mechanical structure relatively simple by minimizing the number of moving components.

The patent implements selective dynamics where lens groups G2, G3, and G4 are moved along the optical axis during zooming while G1 and G5 remain fixed. This partial dynamic configuration achieves high magnification ratios through the interval changes between the movable groups, while maintaining simplified mechanical structures by reducing the number of moving parts compared to designs where all groups move.