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Focus detection apparatus and control method thereof

A technology of focus detection and equipment, which is applied in the direction of focusing devices, instruments, installations, etc., can solve the problems of detection accuracy decline, achieve the effects of reducing capacity, high-precision focus detection, and improving focus detection accuracy

Inactive Publication Date: 2010-11-17
CANON KK
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0020] As shown, depending on the type of light source illuminating the subject, a bright and dark uncompensated area remains between the sensors, thereby causing a decrease in the detection accuracy of the shift between the two images

Method used

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  • Focus detection apparatus and control method thereof
  • Focus detection apparatus and control method thereof
  • Focus detection apparatus and control method thereof

Examples

Experimental program
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no. 1 example

[0052] figure 1 is a block diagram showing an autofocus camera system including a single-lens reflex camera and an interchangeable lens to be mounted on the camera according to an exemplary embodiment of the present invention. The figure mainly shows the optical positional relationship of the system.

[0053] In this figure, a photographing lens 11 is mounted on the front of the camera body 1 . Optical components, mechanical components, electric circuits, and an imaging element such as a film or a CCD are housed in the camera body 1 , enabling pictures or images to be captured. The optical member 2 (hereinafter, referred to as an optical member) as a main mirror is obliquely disposed in the photographing optical path in the viewfinder observation state, and is withdrawn from the photographing optical path in the photographing state. In addition, the optical member 2 is configured as a half mirror that partially transmits or reflects incident light, and when the optical memb...

no. 2 example

[0102] In the first embodiment, compensation is performed by selecting any one of a plurality of pre-stored shading coefficients according to the light source judgment result.

[0103] The second embodiment described below is a typical embodiment that performs a compensation operation different from that of the first embodiment.

[0104] Figure 11 is a flowchart for explaining the automatic focus operation of the camera related to the second embodiment of the present invention. will refer to the aforementioned Figure 14 to illustrate Figure 11 The control flow shown.

[0105] when pressed figure 2 When the switch SW1 on the camera body 1 is shown, the operation starts in step S401. In this case, the camera microcomputer 100 performs an accumulation operation of the line sensors 211 a , 211 b , 212 a , and 212 b in the focus detection sensor 201 . After accumulation starts, the accumulation status is monitored based on a signal from the focus detection sensor 201 . On...

no. 3 example

[0120] The cameras according to the first and second embodiments perform compensation based on light source detection results and a plurality of shading coefficients stored in advance.

[0121] The third embodiment described below is a typical embodiment that performs compensation operations different from those of the first and second embodiments.

[0122] Figure 12 is a flowchart for explaining the automatic focus operation of the camera related to the third embodiment of the present invention. will refer to the aforementioned Figure 14 to illustrate Figure 12 The control flow shown.

[0123] when pressed figure 2 When the switch SW1 on the camera body 1 is shown, the operation starts in step S501. In this case, the camera microcomputer 100 performs an accumulation operation of the line sensors 211 a , 211 b , 212 a , and 212 b in the focus detection sensor 201 . After accumulation starts, the accumulation status is monitored based on a signal from the focus detecti...

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Abstract

A focus detection apparatus that measures, in advance, and stores shading coefficients for light sources of different types, and in a focus detection operation, generates light source information for determining a light source that irradiates an object based on outputs from a plurality of photometry sensors with different spectral characteristics and switches the shading coefficient of a focus detection sensor among shading coefficients stored according to the light source information.

Description

technical field [0001] The present invention relates to improving focus detection accuracy under different types of light sources in an autofocus camera. Background technique [0002] Film / digital single-lens reflex cameras generally use the following so-called TTL (Through The Lens) phase difference detection type focus detection (hereinafter, also referred to as AF) method: The two imaging lenses whose optical axes are shifted form images of the respective light beams on the focus detection sensor, calculate the defocus amount based on the shift between the two formed images, and drive the photographing lens based on the calculated defocus amount. Achieve focus. [0003] Figure 14 An example of a phase difference detection type focus detection device using a secondary imaging system is shown. In this apparatus, a field lens 102 having the same optical axis as that of the photographing lens 101 performing focus detection is arranged near the predicted imaging plane F of ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G02B7/28G03B13/36
CPCG02B7/285G03B13/00
Inventor 一宫敬
Owner CANON KK
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