Home security camera buying guide
John, DIYer & IT developer, Brighton70 guides
- System type
- Focal length
- Analogue camera
- IP camera
Video surveillance: a practical and effective security system
Types of home security camera systems
Dummy cameras are designed to deter intruders and can be used alongside with real surveillance cameras.
Local monitoring uses cameras to send images to your computer, TV or another type of monitor screen in your home.
Remote monitoring uses IP cameras to send footage to your smartphone or computer in real time (requires a 3G internet connection). A great solution for monitoring your property while you're away.
Local and remote monitoring
A system that features both monitoring types can be customised for optimal home security.
- Draw up a plan of the area that you want to monitor, estimating the camera angles you need by placing yourself where the cameras would be.
- Evaluate the benefit of mobile cameras in your location.
- Consider protection against weather and the type of network connections you'll need.
- Think about protecting your cameras against potential acts of vandalism.
Home security cameras: the technical terms
As you have probably noticed, there is no shortage of technical terms and these may prove confusing! Here's a quick run-down:
- Viewing angle: just like the human eye, the angle of view determines the range seen and captured on camera.
- Lens: determines the viewing angle of the camera. The larger the lens, the narrower and more distant the field of vision; the smaller the lens, the wider the field. Lenses range from 2.5 mm to 100 mm in size.
- Focal length: simply put, the focal length (measured in mm) represents the distance between the lens where the image is formed on the sensor. As the focal length increases, the field of view is reduced (25mm = wide angle; 50mm = standard).
- Lens: converges or diverges light, producing an image.
- Aperture: adjusts the quantity of light entering the lens.
- Image sensor: allows the camera to receive incoming light signals. CCD sensors offer better resolution than CMOS sensors.
- Chipset: manages data flow, transforming the light signal into a distinct, precise image.
- Compression format: used to compress data to minimise required storage space. Compression comes in different formats, the best known being MJPEG, PEG4 and H124. Some cameras combine two formats. MJPEG is the most suitable format for motion detector cameras.
- Encoding: refers to process of converting video data into computer format.
- Image sharpness: refers to the sharpness of the image.
- Luminosity: the light level measured in Lux, from 0 to 50,000 (0 corresponding to total darkness and 50,000 maximum luminosity). The number given in a camera's technical specifications corresponds to the minimum amount of light required for the camera to be able to record.
- White balance: a system for correcting image colour.
- Level of protection: standard for ensuring waterproofing / weather protection. If you only remember one number: waterproof models are IP66.
- UPnP (Universal Plug and Play): allows real-time transmission to a TV or other devices on your home network.
Choosing the right focal length
To be selected based on where your camera will be installed, your choice of focal length is crucial as this will determine the area captured on camera.
- 2.1 mm captures up to 14 metres in width at a distance of 6 metres.
- 2.8 mm captures up to 14 metres in width at a distance of 8 metres.
- 3.6 mm captures up to 14 metres in width at a distance of 10 metres.
- 6 mm captures up to 14 metres in width at a distance of 18 metres.
- 12 mm captures up to 10 metres in width at a distance of 24 metres.
IP ratings: degrees of camera protection
The IP code (IP followed by two digits) can be found on all electrical and electronic devices intended for outdoor use.
The figures appearing after the IP represent the device's level of protection against weather. Here's how to interpret the two digits:
First digit: solids
- 0 - not protected.
- 1 - protection against solid objects over 50mm.
- 2 - protection against solid objects over 12.5mm.
- 3 - protection against solid objects over 2.5mm.
- 4 - protection against solid objects greater than 1mm.
- 5 - dust protection.
- 6 - dust tight: protection against all types of dust.
Second digit: liquids
- 0 - not protected.
- 1 - protected against dripping water.
- 2 - protected against dripping water when tilted at 15°.
- 3 - protected from rainwater: water falling as a spray at any angle up to 60°.
- 4 - protected against splashing water from any direction.
- 5 - protected against water projected in jets.
- 6 - protected against water projected in powerful jets.
- 7 - protected against brief immersion up to 1 metre.
- 8 - protected against continuous immersion over 1 metre.
Wired or wireless cameras
Some cameras send images using a network of cables, while others are wireless. Conventional cable networks are more reliable but may involve a more disruptive installation process.
Analogue or IP cameras
Analogue cameras use an older form of technology. They send unprocessed images to a viewing or recording device.
Internet Protocol (IP) cameras shoot in a compressed digital format that is transmitted over an Ethernet network (a computer cable consisting of four pairs of twisted wires), or via Wi-Fi, to a monitoring or recording device. IP images can also be viewed remotely if you have access to the internet.
An overview of image resolution
Resolution is a measure of image sharpness. The higher the resolution, the more useful the surveillance will be as it will contain more more detail. Analogue cameras can vary from 420 to 1000 lines of resolution.
For digital cameras, the following resolution options are available:
- VGA 640 x 480px (pixels)
- SVGA: 800 x 600px
- HD 720P: 1280 x 720px
- HD 1080P: 1600 x 1200px
- HD 3 megapixel: 2048 x 1536px
- HD 5 megapixel: 2560 x 2048px
Different lens types
Camera lenses have a focal range of 2.5–100mm. The larger the lens size, the narrower the field of view and the sharper the image will be from foreground to horizon. Conversely, a smaller or wide angle lens gives a wide field of view. The disadvantage of the wide angle is that you might lose out on detail.
Fixed focus lenses are cheaper but don't allow you to zoom in on items of interest (unlike zoom lenses).
Powering your camera
Your cameras must always be connected to an power source. Camerias are available as 12V, 24V and sometimes even 220V+ models. More powerful devices must be housed in waterproof casing if used outdoors in order to avoid short circuiting the system. This type of casing also provides protection against vandalism.
It's worth noting that some IP cameras are PoE (Power over Ethernet) compatible, which means that the RJ45 Ethernet cable that carries the data, also carries electricity for the camera – provided that the router it's connected to is also PoE compatible.
The advantages of night vision cameras
Some cameras feature a night vision mode, meaning they are designed to capture images in the dark. They go into night mode when the light fades to a certain point, and the images are then captured in black and white.
The basic operation of this mode is very simple: infrared LEDs are positioned around the lens to light up the field of view. The distance over which these LEDs are effective varies from one model to another so it's important to check that the night operating distance of your camera is sufficient for the area you want to monitor.
Home security system regulations
The installation of home security cameras may be subject to legal regulations, and you may have to describe its technical specifications and use to a regulatory authority.
If your cameras are used to monitor a public area or a space where members of the public are welcomed – even partially – further permission may be required. Site plans or appropriate signage may be required by law before you can install your surveillance system.
Spy cameras for additional surveillacnce
Security cameras can be integrated into pens, lighters, clocks, watches, clock radios, and so on. These devices are convenient for additional surveillance, but are very different to the cameras described above.
While some models can be linked to a surveillance system, but most of these 'spy cameras' work as independent units.
Choosing the right home security system
Wired IP cameras with PoE provide an up-to-date and flexible security camera setup. Wi-Fi cameras, on the other hand, allow you to enjoy all the benefits of IP video surveillance with no need for cables. Learning about the optical, electronic, and connectivity features of security cameras will help to ensure image quality and how useful they can potentially be. Depending on where you live and how exposed your cameras are, you might want to check the maximum operating temperature of any cameras used outdoors.
Learn more about home security
John, DIYer & IT developer, Brighton 70 guides écrits
Lacking space, I have not got a permanent workshop and certain tools I dream about but are not part of my collection. Not to worry, I already know a lot about DIY and I have a high-tech profile that I hope will guide you in your decisions!
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