NCJ Number
143638
Journal
Security Management Volume: 37 Issue: 5 Dated: (May 1993) Pages: 41-42,44- 45
Date Published
1993
Length
4 pages
Annotation
This article describes the technology of lenses for closed-circuit television surveillance, so as to assist in the purchase of the appropriate lens for the camera to be used and the surveillance to be performed.
Abstract
The article first discusses the format size of the lens to be selected for the format size of the camera. The author advises that the lens format size must meet or exceed the format size of the camera. Also discussed is the focal length of the lens, which determines the interior length of the lens, as measured in millimeters, and will determine the field of view that the camera produces. A section of the article explains field of view, which refers to the actual picture size, both height and width, that a specific formatted size camera will produce with a specific lens at a specific distance from the subject. Depth of field is discussed as well; this relates to the amount of the picture that will be in focus, both near and far from the camera. The depth of field is determined by the speed of the lens, the angle of the lens, and the amount of light on a specific subject. Other topics discussed are iris and f-stop, 2X teleconverters, wide-angle attachments, and C standard and CS standard lenses.