Title:
AUTOMATIC FOCUSING SYSTEM
Document Type and Number:
Japanese Patent JPH01260410
Kind Code:
A
Abstract:
PURPOSE:To execute normal focusing even when a photographic lens for a different kind of camera having an AF function has been installed by inserting and attaching an auxiliary optical system between an image face of a camera body and the photographic lens and converting the depth of the photographic lens and an allowable circle-of-confusion diameter to values corresponding thereto of the camera body side. CONSTITUTION:An auxiliary optical system 3 is a thin lens and arranges optical axes and inserts and attaches, and separates them between a lens part 1 and an image face 2. Each section of A shows the focal depth (focused depth range) in each stop position, and each section of B shows the focused depth range in each stop position requested by the camera body. Accordingly, it will suffice that a composite system of the lens part 1 and the auxiliary optical system 3 satisfies the focus depth of B in each stop position. When magnification of the auxiliary optical system 3 is denoted as beta, an allowable circle-of-confusion diameter becomes beta times of said diameter before the auxiliary optical system 3 is installed. In such a way, even if an interchangeable lens for a different kind of camera is used, an AF function can be operated normally.
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Inventors:
SHIRAISHI AKIHIKO
Application Number:
JP9011388A
Publication Date:
October 17, 1989
Filing Date:
April 11, 1988
Export Citation:
Assignee:
CANON KK
International Classes:
G03B13/36; G02B7/28; G02B15/02; G03B3/00; (IPC1-7): G02B7/11; G02B15/02; G03B3/00
Attorney, Agent or Firm:
Marushima Giichi