This article takes a look at some of the integral features of CCTV cameras that you’ll need to consider when deciding which one is right for you. While many of these factors may seem straightforward, there’s nothing worse than finding out you ended up purchasing the wrong camera for the job. Learning more about what certain CCTV specifications mean & how they affect performance will help you make a more informed decision.
For the sake of simplicity, we won’t cover details like installation procedures, alarm & network interfacing, interactions with NVRs, etc. These aspects typically vary greatly between models and brands, and is different for every security system.
First up, we’ll have a look at some of the features that most individuals look for in a standard network camera.
Megapixels (MP) and Resolution
The first thing you need to know about megapixels and resolution, is that they go hand-in-hand. A standard 1080p screen (1920 x 1080 pixels) corresponds to 2MP. This is because the 1920 by 1080 pixel screen contains around a total of 2 million pixels, which we shorten by saying “Two megapixel” or just “2MP”. We can get this number by multiplying the pixel dimensions of the screen together and rounding the result to the nearest million.
The second thing you need to know is that bigger doesn’t always mean better. As an example, take a side-by-side comparison of the iPhone 12 with its powerful 12MP camera against a 12MP DSLR camera. Despite both having the same megapixel count, the DSLR would be able to produce an image with superior quality while also allowing for much greater control over fine details.
That being said, for applications like monitoring home residences or small businesses, a greater resolution is typically a good thing. A CCTV camera with more megapixels will generally produce a much sharper and better-looking image. Anything from 2MP through to 6MP would be an ideal size for such applications. CCTV cameras upwards of 6MP tend to move towards more commercial & industrial applications. Cameras in these environments are generally required to monitor larger & more expansive areas. This means that a higher resolution is required to capture finer details or movements that would otherwise be obscured by a lower MP camera.
Even with modern video compression technologies like Hikvision’s H.265+ algorithm, video recordings can take up a very large space. The higher resolution the footage, the more space it will take up. For that reason, it’s important to factor in your data storage options to decide on what’s right for you. If you’re curious to learn a bit more about compression technology, have a look at our Beginner’s Introduction to Video Compression.
In short, the main thing the lens size will do it change your camera’s field of view. The smaller the lens size, the wider the field of view. Smaller lens sizes tend to be ideal for monitoring indoor areas and more self-contained environments like offices, storefronts, home residences, and backyards. Lens sizes ranging from 2.8mm through to 6mm tend to be the most common for such uses. This is largely thanks to the versatility and low costs associated with these cameras, making them ideal for most non-commercial applications.
Conversely, a larger lens size will produce a narrow field of view. As you’d expect, cameras equipped with these larger lenses are generally used for very different environments & applications. An example would be monitoring something like cash registers. As the camera would only need to see the till and whoever uses it, a larger lens size focuses the field of view to only contain the relevant scene. This enables the CCTV camera to capture more detailed, clear, and useful footage. Similarly, larger lenses are often used for more expansive environments. Many of the CCTV cameras used along railway lines and in train stations also have large lens sizes for the same reason.
To avoid limiting a camera to one lens size and hence only one fixed field of view, varifocal lenses are used. These allow the camera to adjust the lens with a small electric motor. Varifocal lenses tend to be more expensive than their fixed counterparts, but offer a number of advantages. The most obvious of which is the increased versatility. Varifocal cameras can be used for a more diverse range of tasks and surveillance requirements without being limited to a specific role. They also allow the user more control over how footage of a scene is captured and are a key component in PTZ cameras.
IR capabilities are an essential part of most security systems, so it’s important to know what you’re looking for. There are a few common terms that you should get to know about:
- IR Range: A CCTV system that has an IR range specified will typically have a built-in IR light. This light is turned when there’s not enough visible light to see (i.e. at nighttime, indoors with no lights, etc). The IR range refers to how far the camera can see under such conditions, using only the built-in IR light.
- Day/Night IR: If a CCTV camera states that it uses “Day/Night IR” technology, this generally will mean that it has no built-in IR lights. In other words, the camera relies on natural light rather than acting as its own light source. Despite not having its own supplementary IR light, these cameras can still be perfectly capable in the dark. To help the camera get enough light to work properly in the dark, something called an “IR cut filter” is often used.
- IR Cut Filter: The sensors in practically all CCTV cameras are capable of seeing light that is completely invisible to us. Surprisingly, around 53% of all light produced by the sun falls within this category. If infrared light isn’t somehow blocked from the camera, this leads to considerable colour distortion in the final image. Day/Night CCTV cameras will use an IR cut filter to block out this light during the day but let it in at nighttime. This effectively allows an IR cut filter to double the amount of light that a camera receives at nighttime when installed outdoors.
Broadly speaking, having a built-in IR light is the way to go. Lower-end Day/Night cameras can often have poor low-light performance in comparison to IR cameras. Additionally, a lack of IR makes them more susceptible to changes in lighting, such as from clouds overhead at night. While this is not always the case (like with this Hikvision CCTV Camera), most individuals would be best off selecting an IR camera with a range that suits them.
If you’d like to learn more about the specifics and intricacies of Infrared tech, have a read of our article on How IR Cameras Work.
Weather & Vandalism resistance
The level of protection a camera needs to offer can vary greatly between different environments. Two dominant code/rating systems are used to assess the durability and weather resistance of devices like CCTV cameras. These are IP (Ingress protection) and IK (Impact protection) ratings. The IP rating is typically used to represent a surveillance camera's weather resistance, or how 'weather-proof' it is. Similarly, the IK rating reflects the camera's vandalism resistance.
These are well defined standards set out by the IEC, and can be invaluable for finding the right camera for the job. You can read more about what the various codes for these standards mean Here. If a product does not include a rating in its specifications, this usually indicates that it likely has no resistance to that respective hazard.
CMOS Sensor & Aperture Size
These two components arguably have the most influence on the image quality and nighttime performance. The CMOS sensor is the part of a CCTV camera that captures light and converts it into a digital signal. While the quality of the sensor itself has a large impact on the final image, manufacturers usually only include information about its size. In this case, the bigger the better. A larger CMOS Sensor, the more light it is capable of absorbing – this in turn results in sharper images with an overall higher quality. Moreover, bigger sensors drastically increase low-light performance in cameras.
The opposite is true for aperture size – the smaller the number, the more light the camera can capture. The example below demonstrates how the size of the aperture restricts the amount of light that the CMOS sensor receives. A camera with an aperture of F1.0 will receive four times as much light as a standard camera with an aperture of F2.0
Hikvision’s ColorVu range takes full advantage of this. This line of cameras incorporates both large apertures and quality CMOS sensors to capture full color footage even in nighttime conditions. If you’d like to learn a bit more about how this technology works, have a look at our article on ColorVu Technology.
Where to Start
Datasheets and specifications of cameras can quickly get overwhelming if you’re not familiar with the CCTV acronyms & lingo. As such, the best place to start is with a price range you’re happy with and an idea of what you need the camera to do. If you understand what you want the camera to do, you can save yourself the hassle of sifting through many details that won’t be relevant to you. Hopefully this article has helped you get familiar with a few of the most essential parts of CCTV cameras.