Imaging Apparatus Flash Control for Bounce Photography Distance Accuracy
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Solution Overview
Problem
In bounce photography, the conventional method of controlling main light emission based on estimated subject distance using pre-light emission can lead to underexposure due to the influence of subject reflectance, as the estimated distance may differ from the actual distance indicated by distance measurement, especially when light is reflected off surfaces like ceilings or walls.
Innovation Solution
An imaging apparatus that adjusts main light emission by combining estimated pre-light-emitted subject distance with lens-focused subject distance, obtained through focus information, to improve accuracy, and includes mechanisms to correct for lens errors and light emission attenuation based on the orientation of the light-emitting section.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If bounce photographing is performed using pre-light emission for distance estimation, then the main light emission can be controlled, but underexposure occurs when subject reflectance is extremely high because the estimated distance becomes smaller than the actual distance
Solution Approach 1:
The patent introduces an optical path length calculation as an intermediary parameter that accounts for bounce photographing geometry. Instead of directly using pre-light emission distance estimation, the system calculates the actual optical path length (from flash to ceiling/wall and then to subject) based on the estimated distance and bounce angle, providing a more accurate basis for main light emission control that compensates for high reflectance effects
Solution Approach 2:
The patent changes the parameter used for main light emission control from the raw pre-light emission distance estimate to a corrected optical path length parameter. This parameter transformation incorporates the bounce geometry and optical path considerations, converting the inaccurate distance estimate into a reliable control parameter that accurately reflects the actual light travel distance
2Device complexity
If only pre-light emission distance estimation is used for main light emission control, then the control process is simple, but underexposure occurs due to significant influence of subject reflectance on distance estimation
Solution Approach 1:
The patent performs preliminary calculation of the optical path length and correction factors before main light emission control. By pre-calculating the relationship between estimated distance, bounce angle, and actual optical path length, the system establishes a correction framework that can be applied during photographing without adding significant real-time complexity
Solution Approach 2:
The patent implements a feedback mechanism where the pre-light emission distance estimation is continuously refined based on the calculated optical path length. The system uses the estimated distance to calculate the optical path, then feeds this corrected path length back into the main light emission control, creating a closed-loop system that compensates for reflectance-induced estimation errors
Data Source
AI summary
To increase the accuracy of adjusting the main light emission. An amount of main light emission is adjusted on the basis of an estimated pre-light-emitted subject distance or information corresponding to the estimated pre-light-emitted subject distance and an estimated lens-focused subject distance. The estimated pre-light-emitted subject distance and the information corresponding to the estimated pre-light-emitted subject distance are obtained by pre-light-emission processing. The estimated lens-focused subject distance is obtained from focus information through a lens. In a case of bounce light emission, in a case where the estimated pre-light-emitted subject distance is smaller than the estimated lens-focused subject distance, a distance made closer to the estimated lens-focused subject distance from the estimated pre-light-emitted subject distance by a predetermined amount is set as an estimated subject distance for adjusting the main light emission.