Choosing a Business Security Camera System

Start with incidents, not cameras

The first question is never "how many cameras". It is "what are you trying to be able to prove?"

Different answers produce genuinely different systems:

• Identify a person. Needs a tight shot at a choke point — a doorway, a corridor, a till. High pixel density over a small area.
• Read a licence plate. Needs a dedicated camera at a fixed angle and distance, with a shutter fast enough to freeze motion and handle headlight glare. A general-purpose camera pointed at a driveway will not do this.
• Resolve a dispute. Needs continuous coverage of the transaction area with enough context to show sequence — who was where, when.
• Deter. Needs visibility more than resolution.
• Monitor a process. Needs a wide overview and reliable retention rather than fine detail.

We ask clients for their actual incident history. What has gone wrong, where, at what time of day. That conversation determines the design far more than square footage does.

Pixels per foot: the number that matters

Camera resolution is meaningless without knowing how far that resolution is spread. A 4K camera covering a 100-foot-wide yard delivers less usable detail than a 2MP camera covering a 6-foot doorway.

The industry measure is pixels per foot (PPF) — horizontal pixels divided by the width of the scene in feet.

A worked example: a 4MP camera has roughly 2,560 horizontal pixels. Covering a 12-foot-wide doorway gives about 213 PPF — comfortably identification grade. The same camera covering a 60-foot loading bay gives about 43 PPF — observation only. Same camera, completely different evidentiary value.

Low light is where cheap cameras fail

Every camera looks acceptable at noon. The difference between hardware tiers shows up after dark, and most incidents happen after dark.

• Sensor size beats megapixels. A 4MP camera with a 1/1.8" sensor will outperform an 8MP camera with a 1/2.8" sensor at night, because larger photosites gather more light. Cramming more pixels onto a small sensor makes low-light performance worse.
• IR versus colour-at-night. Infrared gives usable monochrome images in total darkness but eliminates colour — and clothing colour is often the detail that matters. Colour-at-night sensors need some ambient light but retain it.
• Shutter speed and motion blur. Cameras compensate for darkness by slowing the shutter, which blurs anything moving. A slow shutter turns a walking person into a smear. Specify a minimum shutter speed where motion matters.
• WDR for backlit scenes. A camera facing a glass entrance in daylight will silhouette everyone who walks in unless it has genuine wide dynamic range.

We test every critical position after dark before sign-off. A camera that has only been evaluated in daylight has not been evaluated.

Storage maths, done honestly

Undersized storage is the most common defect we find in systems installed by others, because bitrate estimates are usually taken from a daytime idle scene.

The rough formula:

Storage (GB) = bitrate (Mbps) × 0.45 × hours per day × days retained × cameras

Where 0.45 converts Mbps running for an hour into gigabytes. Typical H.265 bitrates:

Sixteen 4MP cameras at 4 Mbps, recording continuously, retained for 30 days: 4 × 0.45 × 24 × 30 × 16 ≈ 20,700 GB, roughly 21 TB. Allow headroom and RAID overhead and you are specifying around 30 TB of raw disk.

Two traps to avoid. First, night bitrates are higher, not lower — IR illumination and sensor noise defeat compression, and a camera watching a windy car park at night can double its daytime bitrate. Second, motion-only recording saves less than promised, because rain, headlights, shadows and foliage all trigger it. We size for continuous recording and treat motion detection as a search aid rather than a storage strategy.

NDAA, retention rules and privacy

NDAA compliance

Section 889 of the National Defense Authorization Act prohibits certain Chinese-manufactured video surveillance equipment in federally funded projects and for many federal contractors. It reaches further than people expect — including OEM-rebranded hardware where the badge on the camera is not the company that built it.

If you hold or may pursue government contracts, work on publicly funded projects, or lease to tenants who do, specify NDAA-compliant hardware from the start. Discovering the requirement after installation means replacing the system.

Retention

There is no single legal retention period for private commercial video in most jurisdictions, but several forces set one for you: insurance policy requirements, industry regulation, contractual obligations and the practical reality that incidents are often reported one to three weeks after they happen. Thirty days is the common commercial baseline; some sectors require considerably more.

Privacy and notice

California requires consent from all parties for audio recording of confidential communications, which is why we frequently disable microphones on cameras unless a client has a specific, considered reason. Signage advising that the premises are under surveillance is good practice and in some contexts required. Cameras in bathrooms, changing areas and break rooms are prohibited or heavily restricted — this should not need saying and occasionally does.

Cameras belong on their own network

A sixteen-camera system streams continuously, every second, forever. Put that on the same flat network as your staff and your POS and you have created a permanent competitor for bandwidth and a substantial security exposure.

How we build it:

• Dedicated camera VLAN, isolated from business traffic, with no route out to the internet for the cameras themselves
• PoE switching sized properly, with the recorder and switches on a UPS — power loss means no recording, exactly when you may need it
• No port forwarding to the recorder. Remote access via the manufacturer's secure relay or a VPN. Internet-exposed NVRs are among the most reliably compromised devices on the public internet
• Cat6 or Cat6A to every camera, certified, with surge protection on outdoor runs
• Firmware maintained — camera firmware is security software and needs updating like any other

Questions to ask any camera installer

1. What pixels-per-foot will each camera achieve at its target distance?
2. What bitrate did you use to calculate storage, and was it measured at night?
3. Is the hardware NDAA compliant?
4. Will cameras be on a separate VLAN, and how is remote access secured?
5. Is there any mandatory subscription to view or export footage?
6. Will you test every camera after dark before handover?
7. Who owns the recorder and the footage, and can I export without contacting you?
8. What documentation do I receive — as-builts, IP schema, credentials?

The answers separate a system designed around your incidents from a price per camera. Here is how we approach it.