Security Camera Lens Overview

A chain is as strong as its weakest link. This applies to security systems too. For a complete surveillance system to prove its true worth, every small element should work smoothly. A lens is an important component when it comes to fulfilling the very basic purpose of HD IP cameras and that is -- a clear image. There are hundreds and thousands of choices in the market and one might get confused with such an assortment. For someone who wants to decide on the best lens according to their purpose, consider keeping two key points in mind -- focal length and field of view. Technical terms such as the former two, might not be understood by a novice. Here’s a brief description of both: Field of View: It is the extent of the area that can be seen through a lens. Focal Length: It is the measure of the distance up to which a camera can see. The focal length and field of view requirements change according to your purpose. For instance, a 4mm lens provides 70 degrees angle of view with facial recognition up to 35 feet. This much focal power is most suitable for small office and residential security applications. If your video surveillance application requires viewing farther distances, then purchase a security cam with a greater focal power. Which Camera Lens Is Best For Me? Obviously, you want to find the best fit for the lens for your video surveillance purpose. You will be looking at hundreds of options from different vendors. But the first and the foremost thing you need to decide is the distance up to which you want to see. But, keep one thing in mind that with increasing distance the field of view will keep narrowing down. This means that more the focal power, the more is the distance, but lesser is the field of view. How Should I Decide The Focal Length? If you cannot decide on a fixed distance, then a varifocal lens can be your savior. You can first configure the lens for a certain distance. If it suits you, then it’s well and good. Otherwise, zoom in or zoom out the focus of the lens and set your desired distance. There are several ranges for Varifocal lens, viz., 3.5-8mm, 9-22mm and 5-50mm just to name a few. A Varifocal lens is the probably the best option for professional installation as the end user can adjust the focal distance to experiment with what works best for them. Still Not Able To Decide? The above discussion revolves around fixed lens cameras and vari-focal lens cameras, but sometimes the surveillance application demands to quickly change the field of view from narrower to a bit wider one. If this is the case, then there’s one solution – PTZ camera. PTZ stands for Pan Tilt Zoom. A PTZ surveillance camera can move in all directions. It can pan (left and right), tilt (up and down) and zoom (in and out). All the movements can be remotely controlled by a security DVR or a PTZ remote controller and can serve as a go-to choice for someone who cannot decide upon a particular field of view. Even they are not watching what they need to; he/she can change the field of view with the help of a controller. The only major disadvantage of these products is that they are a bit costly. And the moving parts of such products are more prone to wear and tear as compared to other products. rnMore advanced versions of PTZ surveillance cameras are coming to the market which has no mechanical parts. Only the lens of the camera moves in the desired direction. The price of such cameras is still a bit expensive for normal video surveillance applications. So which one is better PTZ or a regular camera? PTZ cams require an extra connection other than power and video cables. Additionally, there should be a dedicated person monitoring the surveillance video and adjusting the field of view based on what’s more important. Concluding from all these reasons, it is better to buy more of non-PTZ cam rather than a PTZ cam, mainly because it will be covered under the same budget and with a better monitoring.