Camera system

Abstract

A camera system includes an interchangeable lens and a camera body. The camera body includes a first detecting unit for detecting an autofocus evaluation value, a second detecting unit for detecting that a position of a focus lens comes close to a focus position before running past the focus position, and a signal generating unit. In an autofocus control, the signal generating unit generates a control signal for controlling a driving unit to drive the focus lens at a first speed before the second detecting unit detects that the position of the focus lens comes close to the focus position, and to drive the focus lens at a second speed lower than the first speed based on a change rate of the autofocus evaluation value after the second detecting unit detects that the position of the focus lens comes close to the focus position.

1 . A camera system comprising an interchangeable lens and a camera body,
 the interchangeable lens comprising:
 a focus lens; and 
 a driving unit configured to drive the focus lens, 
   the camera body comprising:
 an image data generating unit configured to capture a subject image to generate image data; 
 a first detecting unit configured to detect an autofocus evaluation value of an image represented by the image data generated by the image data generating unit; 
 a second detecting unit configured to detect that a position of the focus lens comes close to a focus position before the position of the focus lens runs past the focus position; 
 a signal generating unit configured to generate a control signal for controlling the driving unit; and 
 a transmitting unit configured to transmit the control signal generated by the signal generating unit to the interchangeable lens, 
   wherein in an autofocus control, the signal generating unit generates the control signal for controlling the driving unit to drive the focus lens at a first speed before the second detecting unit detects that the position of the focus lens comes close to the focus position and to drive the focus lens at a second speed lower than the first speed based on a change rate of the autofocus evaluation value after the second detecting unit detects that the position of the focus lens comes close to the focus position.   
     
     
         2 . The camera system according to  claim 1 , wherein the second detecting unit detects that the position of the focus lens comes close to the focus position before the position of the focus lens runs past the focus position, by detecting the change rate of the autofocus evaluation value. 
     
     
         3 . The camera system according to  claim 1 , wherein the signal generating unit changes the driving speed of the focus lens plural times. 
     
     
         4 . The camera system according to  claim 1 , wherein the signal generating unit makes a method for changing a driving speed of the focus lens in the autofocus control different between recording of a moving image and recording of a still image. 
     
     
         5 . A camera body to which an interchangeable lens is mountable, the interchangeable lens having a focus lens and a driving unit configured to drive the focus lens, the camera body comprising:
 an image data generating unit configured to capture a subject image to generate image data;   a first detecting unit configured to detect an autofocus evaluation value of an image represented by the image data generated by the image data generating unit;   a second detecting unit configured to detect that a position of the focus lens comes close to a focus position before the position of the focus lens runs past the focus position;   a signal generating unit configured to generate a control signal for controlling the driving unit; and   a transmitting unit configured to transmit the control signal generated by the signal generating unit to the interchangeable lens,   wherein in an autofocus control, the signal generating unit generates the control signal for controlling the driving unit to drive the focus lens at a first speed before the second detecting unit detects that the position of the focus lens comes close to the focus position and to drive the focus lens at a second speed lower than the first speed based on a change rate of the autofocus evaluation value after the second detecting unit detects that the position of the focus lens comes close to the focus position.   
     
     
         6 . The camera body according to  claim 5 , wherein the second detecting unit detects that the position of the focus lens comes close to the focus position before the position of the focus lens runs past the focus position, by detecting the change rate of the autofocus evaluation value. 
     
     
         7 . The camera body according to  claim 5 , wherein the signal generating unit changes the driving speed of the focus lens plural times. 
     
     
         8 . The camera body according to  claim 5 , wherein the signal generating unit makes a method for changing a driving speed of the focus lens in the autofocus control different between recording a moving image and recording a still image. 
     
     
         9 . An autofocus control method for determining a focus position of a focus lens based on an autofocus evaluation value of an image represented by image data generated by an imaging unit, the autofocus control method comprising:
 detecting that a position of the focus lens comes close to the focus position with a detecting unit, before the position of the focus lens runs past the focus position;   in driving of the focus lens,
 driving the focus lens at a first speed before the detecting unit detects that the position of the focus lens comes close to the focus position, and 
 driving the focus lens at a second speed lower than the first speed based on a change rate of the autofocus evaluation value after the detecting unit detects that the position of the focus lens comes close to the focus position.