Cameras – TV Resolution

In general, traditional CCTV cameras have a resolutions between 420 and 790 Television lines (or TVL). This essentially means that the image produced by a 650TVL camera is compiled from 650 separate horizontal lines of information, refreshed approx 25 times per second (known as ‘frames’). Traditional CCTV cameras usually connect to a Digital Video Recorder (DVR) using coaxial type cabling, and are powered remotely.

IP Cameras on the other hand have resolutions above typically in the megapixel range. IP cameras are commonly referred to as Mega Pixel cameras as they have resolutions exceeding 1.0M pixels. IP Cameras connect to a Network Video Recorder (NVR) or a computer. They usually connect via Ethernet cabling (like computers) and are also powered remotely – usually by the Ethernet Switch they are connected to by a feature called Power over Ethernet (PoE). See our dedicated section for IP Cameras here.

Traditional cameras come in four main housing styles 1/ Dome and 2/ Full Body 3/ Bullet and 4/Covert.

Dome cameras are less obtrusive, and often are tri-axis meaning that they can be mounted to vertical or horizontal surfaces. Full Body cameras on the other hand cannot be mounted to the ceiling due to the style of the bracket or housing (case) which conceals the camera body itself. They are usually more obvious too, and are often chosen to make a statement whilst also fulfilling a practical role – i.e. Petrol stations. Covert cameras as the name suggests are hidden within another device such as a light, PIR or smoke detector.

Both Dome and Full Body cameras can be made to provide pan-tilt-zoom (PTZ) functions. This is usually achieved by utilising a special motorised housing for the camera. PTZ functions are driven by a small console which is usally located near to the operator, or the DVR/NVR. PTZ camera consoles have memory locations which will allow operators or guards to preset and recall several views. For instance, when a customer wants to fill their car with petrol at a servo, the lifting of the nozzle triggers an alarm at the operators console. The operator will activate the pump concerned so the customer can fill their car. At the same time, a PTZ camera will pan, tilt and zoom to a pre-determined location in order to capture an image of the car, pump and customer. This image can then be utilised for identification purposes should the customer fail to pay. After capturing the required image, the camera will automatically return to a pre-set wide view until the next time the pump is used.

Many different camera features are considerations when selecting cameras for a premise; These include…

• Resolution
• Minimum brightness (sensitivity)
• Lens ratio
• Gain Controls
• Black & White or Colour
• Operating voltage

Lighting too is an important consideration when chosing a camera – there needs to be enough ambient light to capture a reasonable image, otherwise the exercise is a complete waste of time.  Sometimes there is not sufficient light and in these cases IR Floods or Cameras with built-in IR illumination can be used.

Contact one of our product specialists about your specific needs so we can design and cost a system just for you.