Auxiliary Camera Focusing System for Film Cameras
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Solution Overview
Problem
Film cameras face challenges in obtaining a reliable distance signal for focusing, particularly due to mechanical issues with auxiliary cameras, lens changes, and the need for precise alignment of optical axes, which complicates depth calculation and results in imprecise focusing, especially in low depth of field conditions.
Innovation Solution
A method using detachably connected auxiliary cameras that output focusing signals to a servomotor, with image calculation units capable of pattern recognition and depth image calculation, allowing for simultaneous distance measurement of multiple motifs and automatic focus adjustment, and the ability to store lens calibration tables for efficient lens changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If auxiliary cameras are pivotable to align optical axes onto the object to be focused, then distance measurement capability is improved, but mechanical reliability deteriorates due to susceptibility to failure and tolerances in pivot movement
Solution Approach 1:
The system separates the auxiliary camera from mechanical pivot mechanisms by fixing the auxiliary camera laterally adjacent to the film camera. Instead of moving the camera to align optical axes, the system uses a rigid fixed position and processes images computationally to achieve alignment, eliminating mechanical pivot failures and tolerances.
Solution Approach 2:
The patent replaces the mechanical pivot system with a fixed rigid mounting arrangement. The alignment function previously achieved through mechanical movement is now achieved through computational image processing and fixed geometric relationships between the auxiliary camera and film camera optical axes.
2Reliability
If auxiliary cameras are fixed laterally adjacent to the film camera, then mechanical reliability is improved, but alignment precision deteriorates due to fixed position constraints
Solution Approach 1:
The patent replaces mechanical alignment adjustments with computational image processing. The fixed auxiliary camera captures images that are then processed to determine distance information, eliminating the need for precise mechanical optical axis alignment while maintaining measurement capability.
Solution Approach 2:
The system transitions from requiring precise three-dimensional optical axis alignment to using two-dimensional image processing techniques. By analyzing the fixed image relationship between auxiliary and film cameras, the system calculates distance information without needing perfect spatial alignment.
3Ease of operation
If lens control system uses separate focusing unit and servomotor, then focusing control capability is improved, but device complexity deteriorates
Solution Approach 1:
The patent integrates the auxiliary camera, image calculation unit, and lens control system into a unified device. This merging reduces the number of separate components and interfaces while maintaining focusing control capability, thereby reducing overall system complexity.
Solution Approach 2:
The auxiliary camera serves multiple functions: it provides distance measurement information for focusing control, enables depth image calculation, and supports both manual and automatic focusing modes. This multi-functionality reduces the need for separate dedicated components for each function.
4Measurement precision
If distance measurement is performed with camera-dependent calibration, then measurement accuracy for current lens is improved, but adaptability deteriorates when lens changes occur
Solution Approach 1:
The system performs preliminary calibration by capturing test images with the auxiliary camera and film camera together before actual distance measurement. This preliminary calibration establishes the geometric relationship between the two cameras, enabling accurate distance measurement that adapts to different lens configurations without requiring full recalibration.
Solution Approach 2:
The patent uses the auxiliary camera to capture a copy image that represents the scene from a known fixed position. By comparing this auxiliary image with the film camera image and using the pre-established geometric relationship, the system determines distance information that is adaptable to different lenses without requiring physical recalibration.
Data Source
AI summary
A method for focusing a film camera, in which at least one auxiliary camera is provided for producing an auxiliary representation of an object to be recorded, from which the desired focus setting is determined and a focusing signal is delivered to the film camera.