Selection of Lens and Resolution in Security Camera System.
One of the most important parameters used in security camera systems is the camera’s image resolution, while another important issue is selecting the appropriate lens for the camera. Both parameters are of vital importance in project design. Choosing inappropriate options for these two parameters will result in inefficiency in the security camera system. This will result in the money paid for the system being wasted without getting the desired outcome.
Currently, FullHD, also known as 1080p resolution, is used most commonly in security camera systems, but this resolution can go up to 4K UltraHD resolution. Here, our needs come to the forefront. As the resolution increases, the amount to be paid for the security camera also increases. If FullHD resolution is enough for our needs, we should use it. However, if monitoring is required in a very important area and the finest details need to be visible, 4K cameras should be used.
Lens selection is also very important in security camera systems. Nowadays, cameras come with varifocal motorized lenses. However, due to cost advantages, cameras with fixed lenses are still commonly used. We use wider angle lenses for closer distances and lenses with higher mm for longer distances. Of course, as mm increases, the lens angle narrows, and therefore the field of view also narrows. These selections can be made in specialized programs according to the need or can be selected in the field through demonstrations.
This is the appearance of a person located 30m away with a 4mm lens on a FullHD camera.
This is the appearance of a person at a distance of 30m using a 12mm lens on a Full HD camera.
As clearly seen from the images above, as the lens angle narrows, the clarity of the person in the camera increases. However, as clarity increases, the camera’s field of view significantly narrows. When using a 4mm lens, there is a 4m dead zone in front of the camera, while at a 12mm lens angle, the dead zone increases to 14 meters. When identifying a person, the lens angle should be increased and the camera should focus on that person.
In the images below, the degree of identification of a person at a distance of 30m is shown when viewed with a 12mm and 4mm lens. Of course, the only difference here is the resolution. Above, the resolution is FullHD while below, it is 4K.
This is the appearance of a person located 30m away from a 4K camera with a 4mm lens.
This is the appearance of a person at a distance of 30m captured by a 4K camera with a 12mm lens.
As you can see from the above images, the image quality of a 12mm lens in a FullHD security camera system is very close to the image quality of a 4K 4mm lens. From this, we can conclude that as camera resolution increases, we can obtain higher quality images in a wider area.
In the image below, it is seen that in order to at least clearly identify a person’s face at a distance of 100m, a 4K camera and a 20mm lens should be used.
This is the appearance of a person located 100m away captured by a full 4K camera with a 20mm lens.
To identify a person who is 50m away, at least a 4K resolution and a 12mm lens security camera should be used.
As seen from the examples above, the design of a camera system project should not be random. It requires calculation and expertise. You should definitely seek support from an expert in your projects.
