The shop camera that actually works: NVR, SD-cards or wifi cams, sized by nights and angles

The shop's camera purchase fails in one of two directions: the system nobody can pull a usable clip from when it matters, or the box of eight cameras pointed at nothing - and both failures come from buying hardware before writing the two sentences that decide it: what you need the footage to prove, and how many nights back it has to remember. This page is the sizing and placement maths for a small Lagos business - the counter, the gate, the store - with the same no-invented-prices discipline and the one legal paragraph the security market skips.

The three system shapes, honestly

• The NVR system: cameras feeding a recorder's hard disk, usually over a single network cable that also carries their power - Power over Ethernet, a genuine standard that turns each camera's install into one run - which in a block-and-concrete building is the honest trade: tidier cabling, fewer dead spots, but the run and the recorder's disk are the whole system's health, so the disk is bought as the surveillance class its datasheet names (the continuous-write kind) and not the desktop drive from the drawer. The recorder keeps the days this page's maths below sizes, and the desk recommends it for any shop where the footage is expected to matter.
• The camera-with-card systems: each unit recording to its own card - cheaper to start, wireless-friendly, and the honest trade is fragmentation: the cards fill on their own schedule, the footage of the incident lives on whichever card happened to be alive, and the theft of the camera is the theft of its evidence. Fine for a kiosk and a gate; not the archive the shop needs.
• The cloud plans: survivable off-site, subscription-priced, and in this climate bound by the connection - the upload at prime time is the plan-reading page's problem again, plus the blackout's gap in coverage; the desk files it as a complement (the critical angle mirrored to the cloud) more than a base.

The two numbers that size everything: nights and angles

Retention is a product, not a marketing figure: the days the shop needs the footage (a week for a till dispute, a month for the regulars' patterns) times the camera count, with the recording's own settings - motion-activated versus continuous, resolution, the compression the recorder uses - as the multipliers; the manufacturers publish exactly this table per recorder class, and the honest move is to ask the installer to show you the number on the spec page rather than say 'plenty'. Buy the disk from the maths, not the box's enthusiasm. Angles beat count every time: four good views - the entrance where faces resolve, the counter at hand height where the money changes hands, the store door, the gate's vehicle line - out-perform eight wide shots of roof; the test at install is the live view from the seated position of the dispute: the till at the till's own height. Night matters more than daytime in a compound, so the camera's low-light claim gets checked the only real way: the after-dark walk-round the installed unit's own footage, not the showroom loop.

The two courtesies the installer never mentions

A camera that sees the road beyond the shop's own threshold is recording the street, the neighbours' gate and strangers' property - the same aim-at-your-own-line rule the home-camera page prints, now with a business's weight: signage that says the premises are under camera is both the courtesy and, under the country's data-protection rules, part of how lawful the recording is, and the footage of customers is personal data held by a business that should keep it for the declared purpose, for the retention it sized, and no longer - the regulator's published guidance is the reference and the desk's boundary: the system that archives faces forever, shared on the shop's WhatsApp the day of a rumour, is the incident that becomes the shop's own case. The practical translation: the monitor stays private, clips are made for named disputes and the police request, and the recorder's admin password is changed the day the installer leaves - the default-credential compromise is the reason some camera networks became the internet's open windows, which is also the one line about the recorder that belongs on the wifi-security page beside this one.

Check before you commit

The recorder's supported disk class and channel capacity (the maker's sheet, not the seller's claim), the cameras' rated night performance and weather class for outdoor units (their spec pages), the PoE budget if the switch's own ports are carrying the power, and a written maintenance month: the quarterly check where someone views each angle, cleans each lens of the harmattan film, and confirms the disk's health - the system that fails quietly for four months fails the only night it is needed.

The verdict, as a rule

Four angles that resolve faces and hands, one recorder whose disk is sized from the maker's table, the cable that carries its own power, signage and a password changed - that is the whole professional answer for a small shop, and every larger quote should be read as padding unless it can point at a number on this page the smaller setup missed.