If you are trying to choose some security camera lens, and you think it is confused for you .
Here are some suggestion for you.
firstly,you shuold to konwn the top 6 features of Lens .
the top 6 features of Lens
1.Fixed lens or varifocal lens
The fixed lens is permanently set; the view field angle cannot be changed.
A varifocal lens allows you to adjust the angle to meet your demand, so it is functional, but it much expensive.
Most PTZ cameras have varifocal cameras for special use.
Fixed lens have 2.8mm, 3.6mm, 4mm, 6mm.8mm, 12mm, 16mm, such common lens.
Varifocal lens common size is 2.8mm-12mm on the market.1/3″
Iris cans control how much light comes through the lenses’ aperture.
When the iris creates a large opening, more light can pass through.
However, it is not the case that the wider the iris, the better images you can get. Too much light can wash out your video and you little light makes the scene dark.So it is vital to pick up a suitable iris type for your purpose.
The fixed and manual iris lenses are typically used for indoor environment where the light stays consistent, such as an office, school or shop.
The auto iris lens, on the other hand, can automatically adjust light changes and is more ideal for outdoor locations where there are light variations.
Hint: Think about where you are going to position the security cameras before diving into the security cameras lens purchase. That will influence the final iris types you pick up.
4.Security camera format
When you look at the listed specification of security cameras, you will notice the numbers such as 1/2″, 1/3″, 2/3″, 1/4″ for the image sensors.
Generally speaking, the smaller the camera format is, the narrower the security camera lens field of view is. For example, a 2/3” image sensor will see wider than a 1/3” one.
That’s the format size of security cameras we are talking about. For lens format size, note that the lenses’ image format, say “2/3 inch image format”, is the maximum size it will allow.
So bear in mind that the format size of a security camera lens should be equal or greater than that of cameras, otherwise the corners of the scene being viewed will be cut off.
5.C or CS Mount lens
C and CS mount are two available options when it comes to security camera lens mount, whose main differences lie in the distance from the image sensor to the lens.
The distance for C Mount is 17.5 mm while the CS Mount is 12.5 mm.
The fisheye lens shape looks like a fish eye. The view angle of the fisheye lens is almost 180 degree.
It is a special barrel distortion security lens, but it can view a panoramic house. Most of them are being used indoor.
How to choose the best security camera lens?
Before make a decision buy a security cameras system, or CCTV security cameras, because the CCTV security cameras are complicated.
You should research to confirm your requirements, consider image sensor, size, scene width, height and distance those factors.
Of course, the lens is not only consideration to buy a security camera.And then ask professional brand's advice.
Most of the professional brands have security cameras kits or CCTV security cameras to make a choice.Example, 3.6 fixed lenses is in use in common for security camera system.2.8 to 12mm lens for varifocal security cameras.