Focus adjustment apparatus, imaging apparatus and lens barrel

Abstract

A focus adjustment control apparatus is provided which includes: a focus detection unit that calculates an evaluation value with regard to contrast of an image via an optical system to detect a focus adjustment state of the optical system; an acquisition unit that acquires from a lens barrel at least one of a maximum value and a minimum value of an image plane movement coefficient that represents correspondence relationship between a movement amount of a focus adjustment lens included in the optical system and a movement amount of an image plane; and a control unit that uses at least one of the maximum value and the minimum value of the image plane movement coefficient to determine a drive speed for the focus adjustment lens when the focus detection unit detects the focus adjustment state.

What is claimed is: 
     
         1 . A camera accessory that is attached to the camera body comprising:
 an optical system that includes a focus lens that moves,   a transmitter that transmits a value indicating the ratio of the amount of movement of the image by the optical system to the amount of movement of the focus lens and information indicating a range in which the value can be taken.   
     
     
         2 . A camera accessory as recited in  claim 1 , wherein the information is a maximum value of the value can be taken. 
     
     
         3 . A camera body comprising:
 a mount to which an optical system including a focus lens is attached,   a receiver that receives a value indicating the ratio of the amount of movement of the image by the optical system to the amount of movement of the focus lens and information indicating a range in which the value can be taken.   
     
     
         4 . A camera body as recited in  claim 3 , wherein the information is a maximum value of the value can be taken.