4. Key Features & Technology

a. Resolution & Image Quality

• MP (Megapixels) — more megapixels = higher detail. Common ranges: 2MP (1080p), 4MP, 8MP (4K). At the moment a popular resolution is 5MP which gives a good balance between quality and price for most applications

• Higher resolution gives more zoom/detail but needs more storage and bandwidth, which costs more in initial investment.

• Wide Dynamic Range (WDR) — camera balances bright and dark areas (e.g., entrance with sunlight behind subject). Instead of setting exposure for the whole image the camera adjusts different parts of the image to produce amuch better image. Most HIK cameras use WDR as standard.

• FPS (Frames per second) — 25–30fps = smooth video, lower fps = choppier motion. CCTV systems can use a lower FPS rate as it does not really affect user enjoyment like it would if you were watching a movie at a low FPS, like an old cine film. Halving the FPS can double your storage capacity.

b. Lens Types & Field of View

• Fixed lens — unchangeable view, common sizes = 2.8mm(~100° wide angle), 4mm, 12mm.  Cheaper cameras use a fixed lens and that's fine if you know in advance the subject you're covering. EG you would spec a 2.8mm lens for a wide angle overview type aplication.

• Varifocal lens — adjustable zoom and focus, typical range 2.8–12mm. More expensive but will accomodate close or far subjects with a simple manual adjustment at the camera.

• Motorised varifocal — zoom controlled remotely via software/NVR. As above but remote controled, and more expensive.

• Focal length — smaller number (2.8mm) = wide, bigger number (12mm) = zoomed/narrow.

• Depth of field — how much of the scene stays in focus; wider lenses give deeper focus.

c. Night Vision & Low Light Tech

• IR LEDs (Infrared) — invisible light, gives black & white images at night. Old tech, cheap but reliable and still relevant.

• IR range — distance IR can reach (20m, 40m, 80m).

• Smart IR — reduces overexposure of close objects at night.

• Lux rating — the minimum light level required for usable image. Modern cameras see quite well in low light, beter than humans.

• 0 Lux with IR — can see in total darkness. 0 lux means complete darkness. These will always be monochrome (black and white) images.

• ColorVu / DarkFighter — brand technologies for colour at night using large-aperture lenses and low light sensors (sometimes assisted with soft white LEDs). These give good colour images at night but some customers do not like the auxiliary lighting they emit. And more expensive than IR or plain low lux cameras. 

d. Camera Body Styles

• Bullet camera — long barrel, easy to aim, acts as a visual deterrent. Can be angled at 90 degrees to its mounting face, eg can look along the building it's mounted on.

• Turret camera — compact “eyeball”, versatile, avoids IR reflection issues. Some can not be angled all the way to 90 degrees. They look smart though.

• Dome camera — neat aesthetic, harder for vandals to see where lens points. The camera is hidden inside a smoked glass dome.

• PTZ (Pan, Tilt, Zoom) — motorised, remote controlled, can zoom and track subjects.

• Mini/PT models — compact versions for indoors or discrete locations.

e. Housing & Protection Ratings

• IP rating (Ingress Protection):
  IP66 = weatherproof, dust-tight
  IP67 = submersible (temporary)

• IK rating (Impact protection): IK10 = vandal-resistant housing.

• Heated housings — used in extreme cold to prevent condensation.

f. Connectivity & Power Options

• IP Cameras (Digital)
  Use Ethernet (CAT5e/CAT6).
  PoE (Power over Ethernet) allows video + power on one cable.
  More scalable and integrates with IT systems. 

• But can add complexity with IP network issues.

• Analogue HD (TVI / AHD / CVI)
  Send HD video over coax (RG59). They encode/decode the image to a high res version
  Usually paired with separate 12V/24V power supply.
  Good for upgrading old coax systems without re-cabling.

• Hybrid recorders (DVR/NVR combo) — accept both IP and coax cameras.

• Most HIK DVRs will accept IP CCTV inputs but may limit resolution/frame rates

g. Special Features

• ANPR (Automatic Number Plate Recognition) — optimised for plate capture. Often a low res camera, usually IP, not often offering a good image other than for ANPR.

• Audio — some cameras include microphones and/or audio output eg 2 way comms with the camera via the phone app. In practice they do not really work very well with poor audio quality.

• Smart features — motion detection, line crossing, intrusion detection, face detection. These are a bit gimmicky but have their uses. Often customers get excited about them but later abandon the idea.

• Onboard storage — SD card slot for backup recording. IP cameras tend to have these and this means you do not have to have a NVR, although you do then need a laptop for access, programming etc.

• Remote access — integration with apps/cloud for customer monitoring. 99% of modern DVR/NVRs have an app and remote access as long as they can get internet access at the NVR/DVR, preferably wired for reliability and speed.

• Baluns allow the use of network cable for carrying analog CCTV signals and can be quite a neat solution as you can simply use and RJ45 for simple reliable connections. You need HD baluns for HD signals and they are sold with a spec, eg 4K HD baluns, or 1080p Baluns. Balun means Balance/un-balance as they adjust the signal in this way.