You may have to know how to choose the right type of CCTV system to protect your premise, but how much do you know about CCTV lenses? Do you know what the CCTV lens mm means? Do you know how to choose the right CCTV lens?
There are many things you need to know when it comes to choosing the right CCTV lens. It can be tricky if you don’t understand well about it. It can be simple as numbers are listed with the CCTV lens, but it can be confusing to know the implications behind the numbers.
You will need to know the insight of the CCTV lens types and comparisons when choosing the CCTV lens. From this article, you will get to know how to choose the right CCTV lens and find the lens that suits you the most.
Types Of CCTV Lens
Before you start choosing your CCTV lens, you will need to understand the types of CCTV lenses. It can be divided into CCTV fixed lens (also known as monofocal lens) and CCTV varifocal lens.
For CCTV fixed lenses, the focal length is permanently set, which means you can’t change the field of view of fixed lens CCTV. If you want to get a CCTV fixed lens, you will need to decide whether you will need a wide-angle CCTV lens or a narrow-angle lens for your situation.
You can adjust the focal length for CCTV with a varifocal lens according to your need. But this type of CCTV lens will be more expensive than CCTV fixed lens.
Many CCTV with the varifocal lens is equipped with motorized zoom lenses, such as PTZ CCTV. CCTV with a motorized zoom lens that adjusts the focal length can get clear auto-focused images compared to CCTV with a manual varifocal lens.
If you need to switch between a wide-angle and a narrow field of view, choosing CCTV with the zoom lens is better. You can control the CCTV’s field of view through the Zoom/Focus buttons on the web interface or the apps.
Factors To Consider When Choosing CCTV Lens
CCTV Lens #1 - Focal Length
CCTV lens size or focal length is measured in mm. This is a necessary term as it determines the field of view, also called the viewing angle.
There are a few sizes for CCTV lenses, such as 2.8mm lens, 3.6mm lens, and 12mm lens CCTV. You may be wondering what’s the difference between the sizes. While the smaller the CCTV lens focal length number is, you can see a wider area but not as detailed. The bigger the focal length, the further you can see, but the narrower view it will be.
CCTV focal length can vary depending on your need. It can be wide angles that allow your CCTV to take in an entire landscape or telephoto lenses that can zoom in on a small object in the distance.
Suppose you need to install your CCTV for large-are places, such as parking lots, warehouses, back yard, or construction sites, CCTV with wide angle lens work best for you. CCTV with a narrow-angle lens will be more suitable for critical entrances such as doorways and cash registers.
CCTV Lens #2 - Aperture
Another factor to consider when choosing your CCTV lens is the aperture. It is the hole that light passes through to enter the CCTV. It is measured in f-stops.
It may sound confusing, but remember that a lower number of f-stops represents a wider aperture. For example, f1.4 is a large aperture, allowing more light to enter the camera.
The aperture is important for a CCTV lens as it can affect the CCTV depth of field, which is the distance between the nearest and farthest objects in the surrounding that appear sharp in an image.
A narrow aperture corresponding with large depth of field can contribute to more objects in focus. You can adjust the CCTV lens aperture to control how much of a scene is in focus. A wide aperture will focus more on objects in front of you but the background will be blurry. In contrast, a small aperture will focus on everything the CCTV captured.
CCTV Lens #3 - Iris
The next factor will be the iris. Iris will control how much light goes through the CCTV lens aperture. The larger the opening of the iris, the more light will pass through.
But it doesn’t mean that the wider the iris, the better the image. Too much light will wash out your video, and too little light will make the scene dark.
It is important to pick up a suitable iris type for your need. For indoor environments, fixed and manual iris CCTV lenses are more suitable as the light stays consistent in offices, shops, or schools.
As there are light variations at outdoor locations, an auto iris lens will be more suitable as it can automatically adjust the light changes.
You will want to consider where you want to place your CCTV before getting your CCTV lens. Think about whether you want to install indoor or outdoor, as it will affect your decision to pick the iris type you need.
CCTV Lens #4 - Camera Format
When browsing through the listed specification of CCTV lenses, you will notice the numbers for the image sensors, such as 1/2″, 1/3″, 2/3″, and 1/4″ .
The smaller the camera format is, the narrower the CCTV’s field of view will be. For example, you can see wider for a 2/3″ image sensor than for a 1/3″ image sensor. If it says “2/3 inch image format”, it will be the maximum size it will allow for the lens format size.
You must remember that the CCTV lens format size should be equal to or greater than the camera you choose, or the corners of the scene being viewed will be cut off. So you will need to double-check the format size of the CCTV and the lens for the best shot.
With the choices of CCTV lenses in the market, you will want to research them before getting one from the shop. A CCTV lens calculator can help you to get the right focal length. If you key in the image sensor size, scene width, height, and distance, you will get the lens focal length that fits your need.
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