Exchangeable lens having a settable aperture and camera body that captures an image by an optical system which has a settable aperture

Abstract

A lens barrel including: an optical system which includes a focus adjustment optical system; an aperture which limits the light beam which pass through the optical system to predetermined range at the time of detection of the focus state of the optical system; a drive which drives the focus adjustment optical system; a memory which stores a first predetermined value which is a aperture value within the predetermined range; and a transmitter which sends the first predetermined value to the camera body.

What is claimed is: 
     
         1 . An exchangeable lens which can be directly or indirectly detachably attached to a camera, the lens comprising:
 an optical system including an aperture; and   a driver which drives the aperture so that an aperture value of the aperture for detecting a focal position of the optical system becomes a first aperture value or less when the aperture value for capturing an image is larger than the first aperture value, and sets the aperture value of the aperture for detecting the focal position of the optical system to the aperture value for capturing the image when the aperture value for capturing the image is the first aperture value or less.   
     
     
         2 . The exchangeable lens as set forth in  claim 1 , wherein
 the driver drives the aperture so that the aperture value for detecting the focal position of the optical system becomes the first aperture value when the aperture value for capturing an image is larger than the first aperture value.   
     
     
         3 . The exchangeable lens as set forth in  claim 1 , wherein
 the driver drives the aperture so that the aperture value of the aperture for detecting the focal position of the optical system becomes a value smaller than the aperture value for capturing the image when the camera captures a dark object.   
     
     
         4 . The exchangeable lens as set forth in  claim 1 , wherein
 the driver drives the aperture so that the aperture value of the aperture for detecting the focal position of the optical system becomes a minimum aperture value when the camera captures a dark object.   
     
     
         5 . A camera comprising:
 an imaging device which captures an image by an optical system including an aperture and outputs a signal;   a detector which detects a focal position where an image by the optical system is focused in the imaging device based on the signal; and   a controller which sets an aperture value of the aperture for detecting the focal position by the detector to a first aperture value or less when the aperture value for capturing an image by the imaging device is larger than the first aperture value, and sets the aperture value of the aperture for detecting the focal position by the detector to the aperture value for capturing the image by the imaging device when the aperture value for capturing the image by the imaging device is the first aperture value or less.   
     
     
         6 . The camera as set forth in  claim 1 , wherein
 the controller sets the aperture value for detecting the focal position by the detector to the first aperture value when the aperture value for capturing an image by the imaging device is larger than the first aperture value.   
     
     
         7 . The camera as set forth in  claim 1 , wherein
 the controller sets the aperture value of the aperture for detecting the focal position by the detector to a value smaller than the aperture value for capturing the image by the imaging device when the camera captures a dark object.   
     
     
         8 . The exchangeable lens as set forth in  claim 1 , wherein
 the controller sets the aperture value of the aperture for detecting the focal position by the detector to a minimum aperture value when the camera captures a dark object.   
     
     
         9 . The exchangeable lens as set forth in  claim 1 , wherein
 the controller controls the aperture value of the aperture for detecting the focal position by the detector on the basis of the signal output from the imaging device when the signal output from the imaging device is smaller than a predetermined value.   
     
     
         10 . An exchangeable lens which can be directly or indirectly detachably attached to the camera body, the lens comprising:
 an optical system including an aperture; and   a driver which drives the aperture so that an aperture value of the aperture for detecting a focal position of the optical system becomes in a range of a second aperture value or more and the first aperture value or less when the aperture value for capturing an image is larger than the first aperture value, the second aperture value being larger than a minimum aperture value and smaller than the first aperture value   
     
     
         11 . The exchangeable lens as set forth in  claim 10 , wherein
 the driver drives the aperture so that the aperture value for detecting the focal position of the optical system becomes the first aperture value when the aperture value for capturing the image is larger than the first aperture value.   
     
     
         12 . The exchangeable lens as set forth in  claim 10 , wherein
 the driver drives the aperture so that the aperture value for detecting the focal position of the optical system becomes in a range of the second aperture value or more and the first value or less when the aperture value for capturing the image is in the range of the second aperture value or more and the first value or less.