Adaptive Focus Control for Interchangeable Lens Aberrations
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Solution Overview
Problem
Conventional image pickup apparatuses face challenges in achieving accurate focus detection due to aberrations and chromatic aberrations, leading to in-focus position shifts, which require large data storage for correction and inefficient firmware updates for interchangeable lenses.
Innovation Solution
An image pickup apparatus with a lens unit that includes a first focus detection unit for contrast detection and a second focus detection unit for phase difference detection, along with a control unit that determines the appropriate focus control method based on aberration-induced in-focus position displacement information received from the lens unit, allowing for adaptive focus control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If phase difference detection method is used for focus detection, then focus detection speed is improved, but in-focus accuracy deteriorates due to aberration and chromatic aberration causing best focus shift
Solution Approach 1:
The patent introduces a communication interface as an intermediary between the interchangeable lens and the image pickup apparatus. This intermediary enables the transmission of lens-specific aberration information from the lens to the apparatus, allowing the system to select or adjust the focus detection method based on the actual lens characteristics, thereby resolving the contradiction between speed and accuracy.
Solution Approach 2:
The patent changes the parameter of focus detection method selection based on lens-specific aberration parameters. By receiving aberration information from the lens and dynamically selecting between phase difference detection (for speed) and contrast detection (for accuracy), or applying correction values, the system adapts the detection parameters to match the lens characteristics, resolving the contradiction.
2Measurement precision
If correction values for every interchangeable lens are stored to correct best focus shift, then in-focus accuracy is improved, but data storage capacity requirement increases extremely
Solution Approach 1:
The patent extracts only the essential aberration information parameters from each lens and transmits them via the communication interface. Instead of storing complete correction datasets for every lens, the system stores and transmits only the necessary aberration characteristics, significantly reducing data storage requirements while maintaining correction capability.
Solution Approach 2:
The patent creates a universal communication protocol that can handle multiple lens types with different aberration characteristics through a single standardized interface. This universal approach eliminates the need for separate large-scale storage for each lens type, as the same communication channel and data structure can accommodate any lens's aberration information.
3Adaptability or versatility
If firmware updating is implemented to correct best focus shift for future interchangeable lenses, then adaptability is improved, but system complexity and update requirements increase
Solution Approach 1:
The patent enables each interchangeable lens to self-report its aberration characteristics through the communication interface. The lens itself provides the necessary correction information without requiring the camera body to be pre-programmed with lens-specific data or to undergo firmware updates. This self-service approach eliminates the need for complex firmware update mechanisms.
Solution Approach 2:
The patent performs preliminary action by having the lens provide its aberration information through communication upon mounting, before image capture begins. This preliminary exchange of information allows the system to immediately configure the appropriate focus detection method or correction values without requiring subsequent firmware updates or complex initialization procedures.
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 enables effective suppression of focus shifts caused by aberrations, improving focus detection accuracy and reducing the need for extensive data storage and firmware updates by dynamically selecting the appropriate focus detection method for each lens.
Implementation Method 1
each of which includes a plurality of photodiodes corresponding to a micro lens
Implementation Method 2
a first focus detection unit configured to perform a focus detection by a contrast detection method based on a signal output from the image pickup element
Implementation Method 3
a second focus detection unit configured to perform a focus detection by a phase difference detection method based on a pair of image signals output from the image pickup element
Data Source
AI summary
An image pickup apparatus on which a lens unit is to be removably mounted includes an image pickup element, a first focus detection unit which performs a focus detection by a contrast detection method based on a signal output from the image pickup element, a second focus detection unit which performs a focus detection by a phase difference detection method based on a pair of image signals output from the image pickup element, and a control unit which performs a focus control based on an in-focus position detected by the first or second focus detection unit, and the control unit receives, from the mounted lens unit, first information related to a displacement of the in-focus position by the phase difference detection method and determines whether to use the second focus detection unit for the focus control according to the first information.