Lens are presented on the market in different modifications, each of which has its own characteristics, specifications. Depending on the performance of optics, applied in various fields. Varifocal lenses are most often found in video surveillance systems. There are several criteria that should be considered when choosing such equipment. Consider them in more detail.
What is it and for what you need?
Varifocal lenses are optical devices that allow you to optimize and change the focal length. The main features of the aggregate include a number of factors.
Optical lenses in the device are located so that they can be adjusted both in manual and automatically. This allows you to adjust the viewing angle in the frame.
Many models range is 2.8-12 mm.
If we talk about static devices, there is no adjustment. The advantage of a static lens is that it can be applied by 3.6 mm.The key parameter is considered a focal length, like any optics. If you need to monitor a major object, the wide-angle camera is best suited.
Such lenses are often installed in parking lots, gearboxes and outputs in various TC.
Low-dimensional optics allows you to clearly see a specific object. With such a lens, you can zoom in scale and get a detailed picture. Often, devices with such optics are operated on industrial facilities, in banks and cash desks. It is safe to say that a megapixel lens is universal.
A bright representative of this category of optical devices can be called TAMRON M13VM246, who has a manual diaphragm and a variable focal length 2.4-6 mm, thanks to which you can get a high-resolution image.
Qualitative aspherical megapixel lens 1/3 format is Tamron M13VM308, Focal length to 8 mm, and the viewing angle is quite wide.
The diaphragm is manually adjusted.
Dahua sv1040gnbirmp has infrared correction, auto-diaphragm and manual focus control. Focal length 10-40 mm. This is a light lens capable of giving a good picture, it is inexpensive.
How to choose?
To find a suitable lens, it is necessary to decide on the purpose of its use and operating conditions. Focal length affects image quality. Optical devices that are used in the production of video surveillance cameras are indicated by F 2.8, 3.6, 2.8-12. The letter F denotes the distance, and the numbers are fixed and focal length in millimeters.
The choice of variofocal lens does this indicator affect. The bigger it will, the less the viewing angle.
If we are talking about installing the camera with the maximum review area, it is better to pay attention to optics with F 2.8 or 3.6 mm. For tracking a cash register or vehicles in the parking lot, a focal length of up to 12 mm is recommended. With such a lens, you can manually adjust the magnification of the camera in place.
You can use the auxiliary means – the calculator of the lenses. With a convenient software, you can get information about which review gives one or another lens. It should be borne in mind that in some devices the IR index is indicated, which means infrared correction. The contrast of the resulting image rises, so the lens do not have to constantly reconfigure depending on the time of day.
How to setup?
You can adjust the variofocal lens yourself. Installation does not take much time, and if you follow the rules, the lens will work as it should. Cameras can be internal and street. The viewing angle varies by adjustment. If it should be wide – 2.8 mm, you need to configure zoom until you stop, and adjust the focus. The image on the screen will be overall.
If you want to focus on a specific part, record a specific object, adjustment is made in the opposite direction – the angle will already be, and the picture approaches. All unnecessary from the frame is cleaned, and the lens is concentrated at a certain place.
Street varifocal lenses are adjusted somewhat differently. It requires a wide viewing angle, if we are talking about tracking the territory. First need to adjust zoom, then make a smooth focus.
The main advantage of such optics is considered to change the equivalent focal length. It depends on the features of the location of the lens, as well as the size of the matrix. Despite the fact that this can be done with a conventional lens, a varifocal device can make changes without increasing the size of the mechanism, which is profitable. For standard cameras, such equipment is not released, although it would facilitate the work of professional photographers who are often forced to carry lens with different parameters. Summing up, it is safe to say that for the video surveillance of the best option than the variofocal object, not to find.
Overview of the variofocal lens for the action cameras in the video below.