Overview of the security cameras
There are four main styles of security cameras: infrared camera, bullet camera, dome camera and box camera. The best security camera depends on some factors such as the location and the position where the buyers want to monitor, the reason why the prospects want to buy, the purpose to use the security camera whether they will use these security cameras inside or outside, during the day or in the nighttime or both of them.
People usually choose bullet style security cameras for their using. They can be used inside or outside. These security cameras have black or white model(s) and they come with all of the required mounting hardware. The casings of security cameras are weather resistant and it do not require added external protection.
Infrared security cameras are also popular as the users are able to see they allow in little or no lighting conditions. They also can be used inside or outside. It has small bulbs installed around the outer edge of the lens that will help the users can see in the dark zone.
Dome security cameras provide the users a different look. The electronics in the camera are the similar of a bullet or box camera, but it has more tamper-resistant.
The box security cameras have the best advantage is that the lens could be changed. When the users will want a special camera lens if they need to see further details. The color box security camera allows the users to change lenses on the camera giving them the ability to zoom into a particular areas.
What are the difference between the CCTV 2.8mm and 4mm lens?
Camera lenses size decide the field of long – range surveillance and the angle of the security cameras observation. Generally, the length of fixed security camera lens is from 2.8mm to 10.0mm. Before buying a security camera, the customer should pay attention about the length. The larger the size of the lens, the more narrow and zoomed in the field of view is. The angle of lens section also relies on the image sensor chip. People have used popular sections are one – thirds.
There are two main types of cameras which are fixed or varifocal lens, how much is its the focal length of the lens, the angle of observation and its long range observation. In some technical guides, you do not see the opening angles; however, you could see the focal parameters. You can refer its parameters in the following information:
- 1 mm equivalent with open-angle 138o36 ‘
- 5 mm equivalent with open-angle 100o24 ‘
- 8 mm equivalent with open-angle 85o36 ‘
- 6 mm equivalent with open-angle 79o36 ‘
- 4 mm equivalent with open-angle 61o36 ‘
- 6 mm equivalent opening angle 46 o12 ‘
- 8 mm equivalent opening angle 34 o24 ‘
- 12 mm equivalent with open-angle 22o42 ‘
- 16 mm equivalent with open-angle 21o30 ‘
Here are some screenshot of Hikvision Security camera on 1, 5, 6, 8, 12, 16 lens
As you can see those information, observation camera has different focal length lenses which are expressed in millimeters. The comparison of the unit 2.8mm lens gives much more coverage of the area, but this does not mean that a lower lens is better. The fixed lenses on the unit 2.8mm will give you the widest view and it is the most common of the security camera. If you want to buy a security camera which see the large viewing angle, you can choose the lens between 4mm and 2.8mm. The size of the imaging device also affects the viewing angle. With smaller devices, it creates narrower angles when used on a lens. The unit 4mm lens will give the observer a 70 degree angle of viewing that will appropriate for using at the residential or small office places. Before buying the security camera(s), please kindly asking by yourself these questions: Do i need to capture video of an office building or the entire store(s)? Or do i need to monitor the particular features, like gateways or exit doors? If the answer is the former, you will need a camera with a unit 2.8mm or 4mm lens. If the answer is the latter, you will be wanting a camera with a unit 6mm or 12mm lens. The lower the number, the wider viewing angle has. The higher the number, the closer your subject points will be discovered.
If you have to monitor both wide angle views and close-ups? In this situation, we think that you should use two or more cameras with different lenses that will be suitable because each camera can be covered their angles and their own areas. If you do not have enough budget to buy various cameras, you could choose one of varifocal cameras which you can see both a wider angle(s) and it will be also zoom in on specific details.
Moreover, you should measure the distance from the location you want to install the security camera to the position you want to observe. You also need to specify the width and height of the frame that you want to monitor. In addition to choosing the appropriate lenses (2.8mm or 4mm), you should consider the location to set the camera and the position to observe. The camera lens with focal length is suitable for observing small areas where need a wide angle such as parking, shopping centers, kindergartens, etc. On the one hand, the camera lens with a large focal length is often placed at industrial parks, national security, etc. because you can observe the objects closer with a big distance.
The size of image items will affect the viewing angle along with smaller products and which creating a narrow angle at the top is used with the lens. The format of the lens is not relevant of the viewing angles. How far you need to inspect will resolve what security camera lens you should use to best fit for your application. If you need to monitor further details, you would buy a camera with higher powered lens. Do not forget that the further ones you want to observe will narrow the field of view in your certain details.