2000-231149 is referenced by 3 patents.

PROBLEM TO BE SOLVED: To prevent the occurrence of a vignetting when a teleconverter is mounted on a camera lens. SOLUTION: When a teleconverter mode is set, or when it is detected that the teleconverter is mounted, or when it is decided based on the photometric values in four corners of a photographic screen that a vignetting occurs, a warning is given in the case when the synthetic focal length (f) is below a prescribed value (fk), and the synthetic focal length (f) is controlled to be equal to or higher than a prescribed value (fk) by optical zooming or electronic zooming. Thus, a photographer can recognize the occurrence of vignetting due to the mount of the teleconverter, and then, the occurrence of a vignetting is prevented.

Title
Camera
Application Number
11-033220
Publication Number
2000-231149
Application Date
February 10, 1999
Publication Date
August 22, 2000
Inventor
Ota Hidefumi
Tsukahara Daiki
Assignee
Nikon
IPC
G03B 17/18
G02B 15/12
G03B 17/14