How to choose a CCTV Camera Lens?

CCTV Lens Guide including example distances
You need to understand the following when choosing a cctv lens:
Focal Length

The Focal Length is measured in mm. As a guide:
a short focal length (e.g. 2.5mm) = a wide angle of view
a long focal length (e.g. 16mm) = a narrow angle of view
the smaller the CCD Chip - the narrower the angle of view
Depth of Field

The Depth of View is the distance within which objects in a picture are in focus.
A large Depth of Field means almost all objects in the Field of View are in focus.
A small Depth of Field means only a small section of the Field of View are in Focus.
The following factors can lead to a greater Depth of Field:
• Using a Wide Angle Lens
• High F-Stop
• Using an Auto Iris
• Camera Format
The size of the camera's CCD image device will affect the angle of view. CCTV Cameras come in different chip sizes - 2/3", 1/2", 1/3" and 1/4".

Click on Image to enlarge



F Stop

F Stop or Aperture has 2 measurements. When the lens is fully open (Maximum Aperture / Minimum F-Stop), just before the lens completely closes (Minimum Aperture / Maximum F-Stop).
F Stop - is the lenses ability to gather light depending on the aperture and focal length.
C or CS Mount

The 2 standard cctv camera lens mounts. The difference between the two is simply the distance between the lens and the ccd image sensor. C Mount - 17.5mm CS Mount - 12.5mm
Auto or Manual Iris

For changing light conditions (e.g. cameras positioned outdoors), Auto Iris lenses are needed.
For indoor use manual iris lenses are sufficient as light levels will not vary too much.
Video or Direct Drive

The majority of CCTV Cameras will be able to use both types. Video Drive Lenses contain circuitry which converts video signal from the camera into iris control. Direct Drive Lenses require the cctv camera to contain the circuitry.

How to choose a CCTV camera lens!

1. To find out what kind of mount for your CCTV lens, C, CS or board. It depends on the camera that a lens works with. Check your camera first.
Board lens thread: M12x0.5, C or CS mount lens thread: 1-1/32”.


2. It is important to understand the angle of the lens. The angle of view depends on the focal.
• The larger the number focal, the narrower the angle of view.
• The sensor of camera (h×v ):
1” sensor: 9.6mmx12.8mm
2/3” sensor: 6.6mmx8.8mm
1/2” sensor: 4.8mm X 6.4mm
1/3” sensor: 3.6mm x 4.8mm
¼” sensor: 2.7mm x 3.6mm
• The formula:
F = v X D /V or f = h X D /H
f: the length of focal
H: the height of the object
V: the width of the object
D: the distance between the camera and the object
h: the height of the sensor in camera
v: the width of the sensor in camera
Example 1, you want to watch an object 8ft wide (V) at 10 ft(D) with 1/3" camera (v=4.8mm). You need a 6mm focal lens (4.8x10/8).
Example 2, you want to watch an object 8ft wide (V) at 165 ft(D) with 1/3" camera (v=4.8mm). You need a 100mm focal lens (4.8x165/8).
That means the object is displayed by full screen on your VGA monitor.
If you do not know where you like to see, you can choose a varifocal lens, for example, 5-100mm, 6-60mm, 3.5-8mm, or 2.8-12mm, 5.5-33mm lens, etc. so that you can adjust the focal to find the best view.


3. A 1" lens can work with a 1", 2/3", 1/2", 1/3" or 1/4" camera. A 2/3" lens can work with a 2/3", 1/2", 1/3" or 1/4" camera. A 1/2" lens can work with a 1/2", 1/3" or 1/4" camera. A 1/3" lens can work with a 1/3" or 1/4" camera. A 1/4" lens only can work with a 1/4" camera.

4. If you need adjust the view of angle, you need choose a vari-focal lens. Otherwise, you can choose a fixed lens to save money.

5. If the light condition changes, you will need an auto-iris lens or a manual-iris lens. An auto-iris lens can be adjusted iris by a camera. A manual-iris lens can be adjusted iris by hand.
For example, if you got an outdoor camera, an auto-iris lens may be what you need. There are DC drives and video drive for auto–iris lenses. Most cameras can support both drive types. It can be selected by a switch on the camera.


6. If you like to see image when IR LEDs turn on, an IR lens would work better.

7. If the camera has a high resolution (>570TVL), a mega-pix lens will give you a clearer image.

8. If you like to see from a small hole, you can choose a pinhole lens.

9. If you have a CS mount camera and a C mount lens, you need to place a 5mm adapter ( Item number: 280143930319 ) between the lens and the camera. Otherwise, it will not work.

10. Extension tubes( Item number: 280116508153) allow you to turn standard fixed focal length lenses into macro lenses. An extention tube kit is available which includes 7 extender tubes: 0.5 mm, 1 mm,2 mm, 5 mm, 10 mm, 20 mm and 40 mm for extension from 0.5 mm to 78.5 mm. The tube(s) mount between the camera and the lens, making it possible for you to focus a C or CS mount lens at a much closer distance than normal.

11. There is a ring in front of most cameras so that you can adjust distance between the lens and camera chip if you need.