Development of the Precision Focus Assistance System for the HDTV Zoom Lens

In this focusing system, a TV zoom lens has a contrast-type auto-focus function incorporated which utilizes differences in optical path length and assists a camera operator in getting his or her focused images precisely in focus. This system, by utilizing the characteristic of the image surface contrast getting maximized when the lens gets focused on an object, controls the focusing lens group so that the high frequency ingredient of the video signals, or the contrast, may be maximized. In order to achieve an auto-focus function that satisfies our requirements for large-size zoom lenses, we have invented a device called the “Precision Focusing System” which has both the contrast-type function and the function which utilizes differences in optical path length. With this system, we have developed an interchangeable lens that incorporates a CCD for focus evaluation and an imaging circuit.

Published

2004-02

Content type

Original Research

DOI

10.5594/M001013

ISBN

978-1-60423-807-5