Camera body for receiving first and second image plane transfer coefficients

Abstract

A lens barrel of the invention includes: an imaging optical system including a focus adjustment lens; a driver that drives the focus adjustment lens in a direction of an optical axis; a transceiver that transmits and receives a signal to and from a camera body; and a controller that controls the transceiver to repeatedly transmit a first image plane transfer coefficient which is determined in correspondence with a position of the focus adjustment lens included in the imaging optical system and a second image plane transfer coefficient which does not depend on the position of the focus adjustment lens to the camera body at a predetermined interval, and, when the controller repeatedly transmits the second image plane transfer coefficient to the camera body, the controller varies the second image plane transfer coefficient over time.

1 . An accessory that attaches to the camera body comprising:
 an optical system including a focus lens; and   a transmitter that transmits a coefficient indicating the relationship between a movement amount of the focus lens and a movement amount of the image plane of the optical system to the camera body;   wherein, the transmitter transmits a first value which is the coefficient corresponding to the position of the focus lens and a second value which is the coefficient and is smaller than the first value.   
     
     
         2 . The accessory according to  claim 1 ,
 wherein, the second value is the minimum value among the first values taken in the moving range of the focal lens.   
     
     
         3 . The accessory according to  claim 1 ,
 wherein, the transmitter transmits a third value which is the coefficient corresponding to the position of the focus lens and a second value which is the coefficient and is larger than the first value.   
     
     
         4 . The accessory according to  claim 3 ,
 wherein, the third value is the maximum value among the first values taken in the moving range of the focal lens.