Focus Detection Correction for Interchangeable Lens Aberration
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Solution Overview
Problem
Existing image-capturing apparatuses face challenges in correcting focus detection errors caused by aberration in the image-capturing optical system, especially when interchangeable lenses are attached, as they do not account for the unique characteristics of captured images produced by different cameras, leading to inconsistent visual focus states.
Innovation Solution
The solution involves an image-capturing apparatus with an image sensor, a focus detector, and a controller that acquires and uses correction values specific to both the image-capturing optical system and the image sensor to perform focus control, ensuring accurate focus detection regardless of camera characteristics. This includes an interchangeable lens with memory to store correction values and communicate with the camera to transmit these values and receive focus control commands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If focus detection is performed using phase difference detection method with pupil division, then focus detection capability is improved, but focus detection accuracy deteriorates due to aberration causing difference between best image surfaces of focus detection pixels and image-capturing pixels
Solution Approach 1:
The patent introduces focus correction information as an intermediary element that mediates between the focus detection pixels and image-capturing pixels. This correction information, transmitted from the interchangeable lens, adjusts the focus detection results to account for aberration-induced differences in best image surfaces, thereby resolving the accuracy deterioration while maintaining the pupil division focus detection method.
Solution Approach 2:
The patent applies parameter changes by dynamically adjusting focus detection parameters based on the specific interchangeable lens being used. Different correction values are applied depending on the lens characteristics, allowing the system to adapt focus detection accuracy to varying optical conditions without changing the fundamental detection method.
2Adaptability or versatility
If interchangeable lens is used with detachable mounting, then adaptability of the system is improved, but focus correction consistency deteriorates across different camera models due to varying pixel pitches and image production algorithms
Solution Approach 1:
The patent applies local quality by customizing focus correction parameters for each specific camera-lens combination. Rather than using a universal correction approach, the system adjusts correction values based on the specific pixel pitch and image production algorithm of each camera model, ensuring consistent focus correction while maintaining lens adaptability.
Solution Approach 2:
The system incorporates feedback mechanisms where the camera provides identification information about its specific characteristics (pixel pitch, image production algorithm) back to the lens, which then selects appropriate correction values. This feedback loop ensures that focus correction remains consistent across different camera models while maintaining the versatility of interchangeable lenses.
Data Source
AI summary
The image-capturing apparatus includes an image sensor configured to capture an object image formed by an image-capturing optical system, a focus detector configured to produce a focus state of the image-capturing optical system to produce focus detection information, a first acquirer configured to acquire a first correction value relating to the image-capturing optical system, and a second acquirer configured to acquire a second correction value relating to the image sensor. The apparatus further includes a controller configured to perform focus control using the focus detection information corrected with the first and second correction values.