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 . An interchangeable lens attachable to a camera body, the interchangeable lens comprising:
 a focusing optical system configured to vary a focal position of the interchangeable lens;   a detector configured to detect a position of the focusing optical system on an optical axis of the interchangeable lens; and   a transmitter configured to transmit a first value and a second value to the camera body,
 the first value indicating a first relationship between an amount of movement of the focusing optical system and an amount of movement of an image plane and being determined based on the position of the focusing optical system detected by the detector, 
 the second value indicating a second relationship between the amount of movement of the focusing optical system and the amount of movement of the image plane, the second value being a minimum value of the second first relationship between the amount of movement of the focusing optical system and the amount of movement of the image plane, 
 when the position of the focusing optical system detected by the detector is a first position, the first value is larger than the second value, and 
 when the position of the focusing optical system detected by the detector is a second position, the first value is equal to the second value, 
   wherein the first value is a first coefficient corresponding to TI/TL where the TL is the amount of movement of the focusing optical system and the TI is the amount of movement of the image plane.