Changeable-lens camera, camera system, and focus detection device

Abstract

A camera system according to this invention comprises an interchangeable lens unit, an intermediate adapter, and a camera body unit. An AF sensor detects the defocus amount of the interchangeable lens unit. The interchangeable lens unit incorporates a data storage section. The data storage section stores first AF correction data and second AF correction data. The first AF correction data is determined by the optical characteristic of the interchangeable lens and associated with the type of the light source illuminating the object of photography. The second AF correction data is determined by the optical characteristic of a system composed of the interchangeable lens and the intermediate adapter and associated with the type of the light source illuminating the object of photography.

1 . A lens interchangeable camera having a lens barrel including a photographic lens, and a camera body, comprising: 
 correction value storage means, disposed in the lens barrel, for storing a correction value which corrects a defocus in accordance with a type of a light source to illuminate a subject;    light source detection means for detecting the light source which illuminates the subject, and outputting a signal in accordance with the light source; and    focus detection means for detecting a focus of the photographic lens,    wherein the focus detection means detects the focus based on an output of the signal detected by the light source detection means and the correction value stored in the correction value storage means.    
   
   
       2 . A lens interchangeable camera having a lens barrel including a photographic lens, and a camera body, comprising: 
 correction value storage means, disposed in the lens barrel, for storing a correction value which corrects a defocus in accordance with a type of a light source to illuminate a subject;    light source detection means for detecting the light source which illuminates the subject, and outputting a signal in accordance with the light source;    focus detection means for detecting a focus of the photographic lens;    correction amount calculation means for calculating a correction amount which corrects an output of the focus detection means based on an output of the light source detection means and the correction value stored in the correction value storage means; and    correction means for correcting the output of the focus detection means based on the correction amount calculated by the correction amount calculation means.    
   
   
       3 . The camera according to  claim 2 , wherein the correction means performs the correction based on the correction amount which continuously changes in accordance with the result detected by the light source detection means.  
   
   
       4 . The camera according to  claim 1 , wherein the light source detection means further comprises light quantity detection means for detecting a light quantity of one of infrared light and near-infrared light of at least the subject.  
   
   
       5 . The camera according to  claim 2 , wherein the light source detection means further comprises light quantity detection means for detecting a light quantity of one of infrared light and near-infrared light of at least the subject.  
   
   
       6 . The camera according to  claim 3 , wherein the light source detection means further comprises light quantity detection means for detecting a light quantity of one of infrared light and near-infrared light of at least the subject.  
   
   
       7 . The camera according to  claim 1 , wherein the light source detection means comprises external light type light detection means which does not use subject light passed through the photographic lens.  
   
   
       8 . The camera according to  claim 2 , wherein the light source detection means comprises external light type light detection means which does not use subject light passed through the photographic lens.  
   
   
       9 . The camera according to  claim 3 , wherein the light source detection means comprises external light type light detection means which does not use subject light passed through the photographic lens.  
   
   
       10 . The camera according to  claim 4 , wherein the light source detection means comprises external light type light detection means which does not use subject light passed through the photographic lens.  
   
   
       11 . The camera according to  claim 5 , wherein the light source detection means comprises external light type light detection means which does not use subject light passed through the photographic lens.  
   
   
       12 . The camera according to  claim 6 , wherein the light source detection means comprises external light type light detection means which does not use subject light passed through the photographic lens.  
   
   
       13 . The camera according to  claim 7 , wherein the correction value stored in the correction value storage means has a form which changes with a change of at least one of a focal length and a subject distance.  
   
   
       14 . The camera according to  claim 8 , wherein the correction value stored in the correction value storage means has a form which changes with a change of at least one of a focal length and a subject distance.  
   
   
       15 . The camera according to  claim 9 , wherein the correction value stored in the correction value storage means has a form which changes with a change of at least one of a focal length and a subject distance.  
   
   
       16 . The camera according to  claim 10 , wherein the correction value stored in the correction value storage means has a form which changes with a change of at least one of a focal length and a subject distance.  
   
   
       17 . The camera according to  claim 11 , wherein the correction value stored in the correction value storage means has a form which changes with a change of at least one of a focal length and a subject distance.  
   
   
       18 . The camera according to  claim 12 , wherein the correction value stored in the correction value storage means has a form which changes with a change of at least one of a focal length and a subject distance.  
   
   
       19 . A focus detection device comprising: 
 a photographic lens;    light source detection means for detecting a light source which illuminates a subject, and outputting output a signal in accordance with the light source;    correction value storage means for storing a correction value which corrects a defocus in accordance with a type of the light source; and    control means for controlling a focus of the photographic lens based on an output of the signal detected by the light source detection means and the correction value stored in the correction value storage means.    
   
   
       20 . The focus detection device according to  claim 19 , wherein the control means calculates a correction amount which corrects an output of the focus detection means based on an output of the light source detection means and the correction value stored in the correction value storage means, and corrects the defocus of the photographic lens based on the calculated correction amount.  
   
   
       21 . The focus detection device according to  claim 19 , wherein the light source detection means further comprises light quantity detection means for detecting a light quantity of one of infrared light and near-infrared light of at least the subject.  
   
   
       22 . The focus detection device according to  claim 19 , wherein the light source detection means comprises external light type light detection means which uses light other than the subject light passed through the photographic lens.  
   
   
       23 . The focus detection device according to  claim 19 , wherein the correction value stored in the correction value storage means has a form which changes with a change of at least one of a focal length and a subject distance.  
   
   
       24 . The focus detection device according to  claim 19 , wherein the correction value storage means is disposed inside the lens barrel including the photographic lens.  
   
   
       25 . The focus detection device according to  claim 20 , wherein the correction value storage means is disposed inside the lens barrel including the photographic lens.  
   
   
       26 . The focus detection device according to  claim 21 , wherein the correction value storage means is disposed inside the lens barrel including the photographic lens.  
   
   
       27 . The focus detection device according to  claim 22 , wherein the correction value storage means is disposed inside the lens barrel including the photographic lens.  
   
   
       28 . The focus detection device according to  claim 23 , wherein the correction value storage means is disposed inside the lens barrel including the photographic lens.