Zoom Lens Focus Control for Blur Reduction During Manual Zooming
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for reducing out-of-focus blur during zooming in lens systems face challenges due to inaccuracies in predicting zoom positions, particularly when using manual operation without a zoom motor, leading to insufficient blur reduction.
Innovation Solution
A lens apparatus and control method that utilize a processor to determine the target position of a focus lens unit based on the predicted position of a magnification-varying lens unit, incorporating phase compensation and PID control to accurately adjust the focus lens position in response to zoom changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a zoom position is predicted using operation amount of the zoom lens, then out-of-focus blur during zooming can be reduced, but prediction accuracy deteriorates when using manual operation without a zoom motor due to large backlash component
Solution Approach 1:
The patent implements feedback control by continuously monitoring the actual zoom position via a zoom position detector and comparing it with the predicted zoom position. The focus lens position is adjusted based on the detected actual position, creating a closed-loop control system that compensates for prediction errors and backlash effects in manual operation modes.
Solution Approach 2:
The patent replaces reliance on mechanical operation amount measurement (which suffers from backlash) with optical/electronic detection using a zoom position detector. This substitution allows accurate detection of the actual zoom position regardless of whether the operation is manual or motor-driven, eliminating the backlash problem inherent in mechanical coupling.
2Stability of the object's composition
If the focus lens position is adjusted based on predicted zoom position, then focus stability during zooming can be improved, but focus accuracy deteriorates when prediction accuracy is low
Solution Approach 1:
The system uses feedback control where the actual zoom position detected by the zoom position detector continuously corrects the focus lens positioning. This closed-loop approach maintains both stability during zooming and accuracy at the final focus position by constantly adapting to the actual zoom state rather than relying solely on predictions.
Solution Approach 2:
The system performs preliminary focus adjustment based on predicted zoom position to maintain focus stability during the zooming process, then applies final correction based on actual detected position to ensure focus accuracy. This two-stage approach combines the benefits of predictive control with precise feedback correction.
Data Source
AI summary
A lens apparatus includes an optical system including a focus lens unit and a magnification-varying lens unit, and a processor configured to control driving of the focus lens unit. The processor is configured to acquire a detected position of the magnification-varying lens unit from a zoom position detector, and determine a target position of the focus lens unit according to a predicted position of the magnification-varying lens unit based on locus information indicating a relationship between a position of the magnification-varying lens unit and a position of the focus lens unit that is in focus at the position of the magnification-varying lens unit, and the detected position of the magnification-varying lens unit.