Focus Detection Correction Using Spectral Characteristics
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Solution Overview
Problem
Existing image capturing apparatuses face increased memory capacity requirements and inaccuracies in focus detection due to aberrations in the image capturing optical system, especially when using AF auxiliary lights with various spectroscopic characteristics.
Innovation Solution
An image capturing apparatus that includes an image sensor and a focus detector, which corrects focus detection errors by calculating and adjusting focus positions based on aberration information and spectroscopic characteristics of different light sources, reducing the need for extensive memory storage by dynamically updating calculation information during focus detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If correction amounts are stored for each AF auxiliary light and each optical state, then focus detection accuracy is improved, but memory capacity increases
Solution Approach 1:
The patent extracts only the essential correction information needed for focus detection accuracy. Instead of storing complete correction amounts for every combination of AF auxiliary light and optical state, it stores only the characteristic values that define the spectral properties of each AF auxiliary light, and calculates correction amounts dynamically based on these extracted characteristics and current optical conditions.
Solution Approach 2:
The patent changes the storage parameters from storing complete correction amounts to storing spectral characteristic values. By storing parameters that define the spectral properties (wavelength distribution, intensity characteristics) of each AF auxiliary light rather than pre-calculated correction values for all scenarios, the system reduces memory requirements while maintaining the ability to calculate accurate corrections adaptively.
2Measurement precision
If multiple correction amounts are stored for different interchangeable lenses, then focus detection accuracy is improved, but memory capacity increases
Solution Approach 1:
The patent creates a universal correction mechanism that works across different interchangeable lenses. By storing spectral characteristic values that are specific to each AF auxiliary light type rather than lens-specific correction amounts, the system develops a multi-functional solution where the same stored characteristics can be used with any lens, and corrections are adapted based on the actual optical state and lens being used.
3Measurement precision
If pre-stored correction amounts are used, then focus detection accuracy is improved, but system complexity increases
Solution Approach 1:
The patent enables the system to self-correct focus detection errors by using stored spectral characteristics to dynamically calculate appropriate correction amounts based on current conditions. Rather than relying on pre-computed correction tables for every scenario, the system serves itself by calculating corrections in real-time using the stored spectral properties and current optical state information.
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
This solution effectively suppresses the increase in memory capacity and accurately corrects focus detection errors caused by optical system aberrations, regardless of the spectroscopic characteristics of the AF auxiliary lights used, enhancing the reliability of focus detection.
Implementation Method 1
an image sensor configured to capture an object image formed from light that enters an image capturing optical system from an object
Data Source
AI summary
An image capturing apparatus includes an image sensor and a focus detector. The focus detector corrects a result of the focus detection by using a difference between a first focus position calculated as a focus position in image capturing by using aberration information of the image capturing optical system and first calculation information according to a spectroscopic characteristic of first light and a second focus position calculated as a focus position in the focus detection by using the aberration information and second calculation information according to the spectroscopic characteristic of the first light, and changes the second calculation information in the focus detection between when second light having a spectroscopic characteristic different from that of the first light is emitted to the object, and when the second light is not emitted.