Consideration for choosing types of CCTV to match the work
- Sensor Format
It is commonly called chip. The size of the sensor affects the number of pixels and the lens to get the view of the image as desired.
The difference between a CCD lens and a CMOS lens is that CCD CCTV provides a clearer picture than CCTV cameras using CMOS lenses.
CCTV that use high quality CCD lens with high resolution is expensive while CCTV using CMOS lens is cheap
CCD stands for Charge Couple Device. It is a sensor that works by receiving light and changing the light to analog signal before sending it to circuit to convert to digital signal.
CMOS stands for Complementary Metal Oxide Semiconductor. It is a sensor that working by change the incoming light into a digital signal immediately using branch circuit. It does not have to transfer to convert like a CCD. In conclusion, CMOS is a circuit that converts light signals in each pixel. The CCD will receive only light and will send the data to the circuit that has the function to convert the signal.
CCTV using CCD lens has better quality and longer lifetime than CCTV using CMOS lens.
CCTV using CMOS lens mostly has low quality and short lifetime. Lens will be deteriorated within 1-2 years. The color of the picture is distorted. Most CCTV using CMOS lenses will be priced at 500-1000 baht, while CCTV using CCD will have better image quality, but the price is higher. CCTV using CCD will be at 1500-7000 baht, depending on the model and resolution. CCTV using CCD have lifetime of up to 7 years old.
Quality of sensor of CCTV does not affect only the sensitivity to light, it also affects the color of the object as well. Good image quality depends on the light intensity at the scene. In the case of CCTV, it is necessary to consider the color temperature of the light source together with the general light source. Because It consists of different types of light and the light around the camera will change over time. So, the light is not always fixed. Determining the illumination of the CCTV (LUX) must consider the brightness of the area where taken by the camera, the reflection of the light at the scene, the distance of the object to the camera that may results in loss of light. The type of lens is also needed to be considered.
In general, CCTV cameras using CCD are classified according to their 3 levels of illumination.
– CCTV cameras used in general business requires brightness from 5-2000 Lux.
– High security CCTV requires brightness 0.1-5 Lux
– CCTV cameras used in specialized operations requires brightness from 0.0001-0.1 Lux
In general, CCTV has a built-in syncronization circuit itself. Each camera’s syncronization will not located at the same area. If we bring many CCTVs to use together through the image sequencer and display on the monitor. It is noticeable that while the sequencer switches from one CCTV to another, the image will shake vertically on the monitor. This will affect the video recording. When the video tape is played, the picture is dropped following to time when the image switched.
High resolution CCTV cameras deliver clear images. This feature is the basis for choosing the type of CCTV. However, it depends on the design of each factory to suit different applications.