Focus Adjustment Apparatus with Diaphragm Correction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing focus adjustment systems in cameras face challenges in maintaining accurate focus detection and adjustment when the diaphragm aperture diameter changes, leading to potential out-of-focus images and unnatural image recording during moving image capturing, due to errors in vignetting correction and discontinuous focus adjustment states.
Innovation Solution
A focus adjustment apparatus that includes a diaphragm aperture adjustment unit, a focus detection unit, and a detection result correction unit, which calculates a reduced defocusing amount correction value after a predetermined change in diaphragm aperture area and adjusts the focus accordingly to minimize discontinuity and errors in focus detection results.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If focus detection is performed using light flux passed through the photographic lens, then focus detection can be executed, but when the diaphragm aperture diameter changes, errors in vignetting correction occur leading to inaccurate focus detection
Solution Approach 1:
The system performs focus detection at multiple diaphragm aperture diameters before the actual capture, and preliminarily determines the optimal diaphragm aperture diameter and focus position combination. This preliminary action ensures that when the diaphragm aperture changes during capture, the focus is already optimized for the new aperture size, preventing vignetting correction errors from causing focus inaccuracies.
Solution Approach 2:
The system actively changes the diaphragm aperture diameter parameter during the focus detection process, performing focus detection at multiple different aperture sizes. By varying this parameter and selecting the optimal combination of aperture diameter and focus position, the system adapts to different lighting conditions and depth of field requirements while maintaining accurate focus detection without relying on potentially erroneous vignetting correction.
2Adaptability or versatility
If the diaphragm aperture diameter is adjusted during imaging, then light reception amount and blur amount can be controlled, but focus detection and adjustment become affected leading to out-of-focus images
Solution Approach 1:
Before actual image capture, the system preliminarily performs focus detection at multiple diaphragm aperture diameters and determines the optimal focus position for the intended aperture setting. This preliminary focus adjustment ensures that when the diaphragm aperture is adjusted during capture for controlling light reception and blur effects, the focus remains accurate and the image does not become out-of-focus.
Solution Approach 2:
The system maintains continuous focus optimization by performing focus detection across multiple aperture settings and interpolating or selecting the optimal focus position that corresponds to the actual capture aperture. This continuous approach ensures smooth transition and maintains focus accuracy even as the diaphragm aperture diameter changes during the imaging process.
3Measurement precision
If focus adjustment is executed based on detected defocusing amount, then focus can be corrected, but discontinuous focus adjustment states occur during moving image capturing
Solution Approach 1:
The system preliminarily performs focus detection at multiple diaphragm aperture diameters and determines the optimal focus position before capture. By having multiple pre-determined focus positions corresponding to different aperture settings, the system can smoothly transition between them during moving image capturing, preventing discontinuous focus adjustment states and maintaining stable, continuous focus throughout the sequence.
Solution Approach 2:
The system dynamically selects the appropriate focus position based on the current diaphragm aperture diameter during moving image capturing. By making the focus position adaptive and dynamic rather than fixed, the system maintains continuous and smooth focus adjustment even as aperture settings change, preventing abrupt discontinuities in the focus state throughout the video sequence.
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 ensures continuous and accurate focus adjustment, reducing the likelihood of out-of-focus images and maintaining a natural image recording experience during electronic viewfinder observation and moving image capturing by effectively managing the impact of diaphragm aperture changes on focus detection.
Implementation Method 1
an image sensor is used as a focus detection sensor... an image on a set of focus detection sensors by the secondary imaging optical system
Data Source
AI summary
A focus adjustment apparatus includes a diaphragm aperture adjustment unit configured to adjust a diaphragm aperture area of a photographic lens, a focus detection unit configured to detect a defocusing amount by using a pair of light fluxes passed through different areas of the photographic lens, a detection result correction unit configured to calculate, during focus detection after the diaphragm aperture area has changed by a value equal to or larger than a predetermined value, a reduced defocusing amount correction value with respect to the defocusing amount, and a focus adjustment unit configured to execute control to adjust a focus based on the defocusing amount correction value.