Video signal

Most cameras have a standard composite video output signal (described as 1Vpp 75 Ohm). You can directly connect camera output to the TV or a video recorder. This is the best choice, cheap and widely used. Because it uses an analog signal, you need an extra equipment to connect it to a computer, but in most cases it is not necessary – you can use standard video monitor. Video to USB converter costs about 50&euro , TV or video PCI cards are even cheaper.
To connect a camera to analog monitor, you need a 75 Ohm cable. But if the length of cable is less than 100m you can use an ordinary cable (twisted wires). For long cables you need a converter (very simple to build).

There are other solutions, like firewire or even RS-232. I see no any reason to use firewire, maybe if you want to use video camera with firewire input as monitor. I expect only problems when using firewire, especially with maximum length of the connection cable.

One (and the only) good thing about an RS-232 camera is that you can plug it directly to the computer. The very bad is that it can provide only 3 frames per second! This is right solution if you like to watch static images.

Power

Many cameras are powered by 12V, some 5V. Consumer video cameras (VHS, DV, Hi8) needs the same voltage as its batteries, e.g. 7.2V. If your robot is powered by 12V try to choose 12V camera. For other voltages you need voltage converter.

Resolution

Resolution of CCTV cameras is defined by number of lines (TVL). More lines means more details on the screen. Typical values are from 320 to 470 lines. There are cameras with 600 lines but use it only if you have unlimited budget.

Lens

A very important part of the camera. For most CCTV cameras you need to buy lens separately. Parameters of lens worth to mention:

• Aperture size. Greater number – you need more light. F1.2 is very good, F2.0 average.
• Field of view. Depends on focal length. Greater focal length – narrowed angle of view.

Sensor

There are two types of sensors: CCD and CMOS. All cheap cameras have CMOS sensor. More expensive and consumer video cameras have CCD sensor. Most important parameter of sensor is sensitivity. This is minimum amount of light that camera needs to proper work. Less number means better parameter. 0.1lux – very good, 1lux – average, 3lux – rather bad. Note that some cameras have Sensitivity 0lux. It means they can work in infrared range and thus you need an extra infrared lamp. Black and white sensors have usually better sensitivity then color ones.
Sensitivity depends on aperture size of lens. Its value is always given with aperture size, like 0.3lux/F1.2. You can improve sensitivity using lens with better parameters.

What to choose

I bought 2 cameras:

• High sensitivity B/W PCB camera for navigation
• an old second hand consumer camera as secondary colour vision and video recorder

There 3 options you can consider:

Camera	Good	Bad
Consumer camera. Size: 250×190×50mm	Good lens x14 zoom, auto and manual focus. Can show date, time on screen. Ability to record video. Easy to interface with microcontroller. Cost about 40€	The size and weight. Power consumption.
PCB camera. Size: 32×32×16mm	Cheap (40-50€). Small and light. Low power consumption (200mA/12V). The camera can be installed in very small housings.	No auto focus and zoom. No remote manual focus. Low quality lens.
CCTV camera (without lens on the picture). Size: 50×50×110mm	Various types of lens available. Auto focus. Small size. Low power consumption (200mA/12V).	Price (75€ and more). Good lens cost too much. Hard to control focus/zoom by microcontroller.