Retail Theft Prevention: How to Choose the Right CCTV System?

2025-02-28 | Security & Surveillance

Pick cameras, lenses, recorders and storage for CCTV that identifies people.

CCTV Installation Guide: Decide What You Need to See Before Buying Anything

The most common CCTV mistake is not buying too cheap — it is buying equipment before deciding what you need to see. No single camera can watch an entire premises and still capture faces and number plates clearly. Before planning a CCTV system, answer three questions: what do you need to see (overview or identification)? Which spots must be identified clearly? Is there light at night? Once those are answered, the rest of the choices become much clearer.

This guide walks through camera types, resolution, focal length, night vision, recorders, storage, power, outdoor protection, privacy compliance and a buying checklist, so you can plan a system that sees clearly and records reliably.

1. Camera Types: Separate "Overview" from "Identification"

A camera is not better because it costs more — it is better when it is in the right place doing the right job. When planning, separate two roles: "overview cameras" that watch the big picture (who came in, where they went) and "identification cameras" that capture detail (faces, number plates, till transactions). Expecting one wide-angle camera to cover a whole shop and identify faces at the same time is unrealistic.

• Bullet: Clearly visible, strong deterrent, suitable for outdoors, entrances and car parks. A fixed lens only looks in one direction, so confirm the coverage angle before installing.
• Dome: Low-profile, hard to tell where it is pointing, suitable indoors. Adjusting the angle is more troublesome, and a dirty cover can affect IR night vision, so clean it regularly.
• PTZ: Can be remotely panned, tilted and zoomed, good for tracking across a large area. But it only looks in one direction at a time — while it turns, that is a blind spot — and it needs an operator or preset patrols. Prices are generally higher.
• Fisheye / panoramic: One unit gives a 360° overview, but edges distort and need de-warping to view comfortably. Not suitable for long-distance face or number-plate identification — add narrow-angle cameras for those spots.

Pairing principle: use overview cameras for entrances and main routes first, then add narrow-angle cameras at identification points such as tills, entrances and vehicle entries. The same layered approach works for large sites — see our school CCTV solution for area-by-area planning.

2. Resolution and Focal Length: Resolution Does Not Equal Identification

Common resolutions: 720p (1280×720, 0.92MP), 1080p (1920×1080, 2.07MP), 1440p (2560×1440, 3.69MP) and 4K (3840×2160, 8.29MP). 4K has about 4 times the total pixels of 1080p, not 2 times. But resolution does not equal identification ability — distance, focal length, light and compression all affect how clear the final image is. High pixels with the wrong focal length and position still will not identify a face.

The rule is simple: the shorter the focal length, the wider the angle and the less distant detail; the longer the focal length, the narrower the angle and the more distant detail. Varifocal lenses (e.g. 2.8–12mm) can be adjusted on site, which suits spots where the distance is only confirmed at installation. A common mistake: mounting one 2.8mm camera high up and expecting it to cover the whole shop and read the till — wide angle plus height plus distance adds up to insufficient detail.

3. Night Vision: IR, Starlight and White-Light Fill

Clear in daytime does not mean clear at night. The main night-vision approaches each have trade-offs:

• IR infrared: Infrared LEDs produce a black-and-white image. An IR Cut Filter blocks infrared in daytime and moves away at night. A manufacturer's stated IR distance is a reference under ideal conditions, not an identification distance. Note: IR reflects off glass — filming outdoors through glass leaves the whole night image washed white.
• Starlight: Keeps colour in low light, but still needs some ambient light; in true darkness it still needs IR.
• White-light fill: Keeps colour and deters intruders, but consider light nuisance to neighbours or passers-by.

Always test at night during handover — do not test in daytime only. A camera that looks fine by day may see nothing at night because of IR reflection or insufficient light.

4. Recorders and Storage: NVR vs DVR

There are two main recorder types. Which one to choose depends on your cameras and cabling:

Hybrid recorders (XVR) can take both analogue and IP cameras, suiting phased upgrades (depending on model). ONVIF helps cross-brand interoperability, but does not mean every feature works across brands. Note: local NVR recording does not need the internet — the internet is only needed for remote viewing and apps.

Codec: H.264 vs H.265. H.265 is widely recognised as saving about 40–50% of storage space; the actual saving depends on scene content and settings. Encoding and decoding are more compute-heavy, and older equipment may not support it. Note that a manufacturer's H.265+ is each brand's own optimisation, not a unified standard — confirm recorder and camera support each other before buying.

How is storage calculated? Formula: storage (GB) = bitrate (Mbps) × 3600 × recording hours per day × days × number of cameras ÷ 8 ÷ 1024. Worked example (the figures below are assumptions to demonstrate the calculation; real bitrates vary with the scene): one 1080p H.265 camera, average bitrate 2 Mbps, 24-hour continuous recording, 30-day retention, needs about 633 GB. There are many variables: bitrate is not fixed, and frame rate and recording mode (continuous vs motion detection) matter. How much motion detection saves depends entirely on activity at the site — there is no universal figure, so do not guess when planning.

Which hard drive? Surveillance-grade drives are designed for 24/7 continuous writing and many simultaneous write streams; ordinary desktop drives are designed for intermittent use. Surveillance-grade drives carry a higher annual workload rating (depending on model). A NAS drive is not a surveillance drive — they are optimised in different directions. A desktop drive that "fits and records" is not necessarily suited to long-term 24/7 use, and the failure risk is higher.

5. PoE Power and Cabling

PoE sends data and DC power over the same network cable, removing the need to run a separate power feed to every camera. Two roles: PSE (power sourcing equipment, e.g. a PoE switch) and PD (powered device, i.e. the camera).

• Active PoE (IEEE standard): detection and classification mean it will not power non-PoE equipment — safer.
• Passive PoE: no detection, so wrong connections risk damage. Check the specification before buying.

Common standards: 802.3af 15.4W (about 12.95W at the device), 802.3at 30W (about 25.5W), 802.3bt 60W (about 51W) / 90–100W (about 71W+). Standards are backwards compatible. When budgeting power, note that a switch's total power is not port count × max per port — add up all cameras with IR fully on at night, plus a reserve. Cabling and network planning also affect stability; for office sites, plan them together with your office network.

6. Outdoor Installation: IP Ratings and Common Mistakes

Outdoor cameras need an IP rating (IEC 60529): the first digit is dust protection (6 means dust-tight), the second is water protection. IP66 means dust-tight plus protection against powerful water jets; IP67 means dust-tight plus short-term immersion (1 metre for 30 minutes). Note that IP67 does not automatically mean more waterproof than IP66 — the tests differ. For outdoor installation, IP66 is generally recommended as a minimum.

Check these common installation mistakes at handover:

• Backlight: camera facing a door or window turns incoming faces into silhouettes.
• Blind spots: corners and areas behind shelves uncovered; a PTZ also has blind spots while it turns.
• Exposed cabling: exposed cable is easy to damage and lets water in.
• Angle too high / too low: too high sees only the tops of heads; too low is easy to block or damage.
• Insufficient storage: no reserve, so recordings are overwritten before the retention period ends.
• Daytime-only testing: IR reflection or low light at night never shows up in a daytime test.
• Filming outdoors through glass: IR reflection at night washes the whole image white.
• Changing obstructions: shelves moved or plants grown to block a camera, never re-checked afterwards.

7. Privacy and Compliance: PDPO Essentials

CCTV is not only a technical matter — it carries privacy responsibilities. Under the Personal Data (Privacy) Ordinance (Cap. 486) and the PCPD's CCTV Guidance, images of identifiable people may count as personal data. Key points:

• DPP1 (collection purpose): there must be a lawful purpose; do not install where there is a reasonable expectation of privacy (e.g. toilets, changing rooms); avoid covert cameras; assess whether a less intrusive alternative exists.
• DPP5 (transparency): post a notice in a prominent place at the entrance, stating the data user, contact method and purpose.
• DPP2 (retention): do not keep footage longer than needed. The PDPO sets no fixed retention period — do not assume "30 days is mandatory".
• DPP3 (use): footage may only be used for its original purpose — do not upload it to social media.
• DPP4 (security): access control, password management, and encryption of transmission and storage.

Cameras should only cover your own premises or the area genuinely needed, and avoid excessive filming of neighbours' doors or opposite units. This article is for general reference only and is not legal advice; consult a professional for your specific situation.

8. Buying Checklist: Ask Every Question Before Work Starts

• ☐ What do you need to see? What is the purpose (theft prevention, dispute evidence, operations)? Which spots need identification (faces, number plates, tills)? Is there light at night? Is audio needed?
• ☐ Cameras + focal length: which spots get overview cameras, which get identification cameras? What focal length for each identification point?
• ☐ Recorder + storage: NVR or DVR (or XVR for phased upgrade)? H.264 or H.265? Calculate storage with the formula and leave a reserve.
• ☐ Power + cabling + network: does the PoE switch power budget cover everything (including all IR on at night)? How is cable routed, and protected against damage and water?
• ☐ Privacy + compliance + maintenance: is the notice posted? Is the retention period set? Who can view footage? Is there a routine check (camera cleaning, angle, obstructions, storage) with someone responsible?

Follow this checklist and most common mistakes are avoided before you buy. If the right combination is unclear, have a professional team assess the site before finalising the plan.

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