Choosing The Right Specs For Your CCTV

I’ve been in UAE for almost two years now. I’ve been for many type of installation. AV, CCTV, Data.. etc.
I’ve been assigned to install a CCTV system to one of our client. It was just a simple CCTV installation, 2 dome cameras, 4 ch DVR and a monitor. When I finished the installation, I then configure the system and noticed the resolution of the camera is not quite good. I’m wondering the problem is with the cable we used, so what I did is I removed the camera then connected it directly to the DVR with a short cable. Still it has a poor image.
Luckily the client didn’t notice the poor image, maybe because he was too happy to have a CCTV system in his office.
When I arrived at home, I tried to open the internet about CCTV cameras and this is what I’ve seen.
Types of CCTV camera:
1. Indoor Cameras.
– As the name implies, indoor camera is used for indoor security purposes. Used mostly in homes, school, offices, hotels and depending upon the security needs.

2. Outdoor Cameras.
– Camera used for outdoor purposes. Mostly used in the entrances and exits of the buildings. It is usually place in an enclosure or a hard shell vandal proof casing.

3. IR Day/ Night Camera
– Mostly used in high alert security areas for 24 hour surveillance.  In day time, this camera functions as a normal camera while in night time it automatically switches low-lux black and white mode and infrared automatically illuminated for full surveillance at night.

4. Dome Camera
– Dome camera is usually installed in public areas such train stations, terminal stations, etc… It is usually installed inside a dark  dome so that it would not be noticeable.  This camera can be rotated or tilted manually.

5. Vandal Proof Camera.
– Usually used as an outdoor camera. This camera is sheltered by  solid enclosure and is covered by a break- proof glass which does not effect its video streaming. This camera is recommended for high surveillance area.

With this types of camera, we can now assume what camera we needed for depending our specifications.
This are the specifications for the camera you have to choose for so that you would have a perfect surveillance system.
1. 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
2. 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″.

Approximate Horizontal angles of view for CCD Chip Cameras
Focal Length	2/3″	1/2″	1/3″	1/4″
2.0mm	-	-	-	82
2.8mm	-	-	86	57
4.0mm	-	77	67	47
4.8mm	83	67	57	40
6.0mm	70	56	48	32
8.0mm	56	44	36	25
12mm	39	30	25	17
16mm	30	23	17	13
25mm	18	15	12	8
50mm	10	7	6	4

3. 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.

4. 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

5. 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.

6. 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.