Residential Security, Access Control, and Surveillance Copyright © 2005 Heathkit Company, Inc. All Rights Reserved Presentation 16 – The Camera Lens
2 Objectives At the end of this presentation, you will be able to:
3 Explain the difference between a CS and C mount. Explain the difference between a video and DC automatic iris. Explain how an automatic iris works.
4 Define aperture, focal length, iris, depth of field, and f-number. State the general relationship between the focal length and the field of view of a typical lens. State the general relationship between the f-number and the maximum width of the iris opening.
5 Lens Characteristics Mount Type Focal Length Maximum Aperture Size Motorized Controls
6 Lens Mounts Standardized types C CS
7 C Mount CS Mount
mm C-Mount CCD
mm CS-Mount CCD Back Lens Element
mm CCD 5mm Spacer 17.5 mm
11
12 Focal Length Distance between the center of a lens and the camera’s sensor Shorter focal lengths display a wide area Longer focal lengths allow close-ups
13 Focal Length Angle of View Type 1.6 mm110°Ultra-wide 2.8 mm80°Wide 4 mm60°Normal 12 mm20°Telephoto 50 mm5°Telephoto 100 mm4°Long Telephoto
14 5°, 50 mm 30°, 16 mm 57°, 3 mm Lens CCD Sensor
15
16 Iris/Aperture Controls the amount of light that strikes the sensor Size is given by the f-number, or f-stop Smaller f-numbers mean larger apertures Larger f-numbers mean less light
17
18
19 Over-exposed image Under-exposed image
20 The Auto-Iris
21
22
23 Light Sensor DC Voltage DC Drive
24 Light Sensor Video Signal Video Drive
Residential Security, Access Control, and Surveillance Copyright © 2005 Heathkit Company, Inc. All Rights Reserved End