CCTV Camera Types: Fixed vs PTZ vs Fisheye, IP Ratings, Lux Ratings and Lens Selection for UK Conditions

Quick Answer: For most UK external CCTV, a fixed IP dome or bullet camera at 4MP (2688×1520) with built-in IR illumination to at least 30m and IP67 weatherproofing is the standard specification. PTZ cameras are used for wide-area coverage requiring operator control or auto-tracking. Fisheye cameras cover 360° in one location but sacrifice pixel density — suitable for room overviews, not for identification. For UK outdoor conditions, choose cameras rated IP66 or IP67, IK08 or higher for impact resistance (external), and capable of operating to -10°C or lower.

Summary

Camera selection determines the usefulness of a CCTV system. A high-quality recording and monitoring setup is worthless if the cameras cannot capture usable images in the conditions they are deployed in. The most common installation failures in UK CCTV are:

  1. Inadequate resolution at the point of interest (camera covers a wide area but cannot identify individuals)
  2. Inadequate IR illumination (camera appears to work but footage is too dark for verification at night)
  3. Wrong IP rating (moisture ingress damages the camera or reduces image quality)
  4. Wide dynamic range (WDR) not enabled or inadequate (bright windows or sun cause the rest of the image to appear black)

This article covers the main camera types and selection criteria for UK domestic and commercial installations. It does not recommend specific brands — focus on specification criteria that any camera must meet.

Key Facts

Quick Reference Table

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Camera Type Best Use Case Pixel Density at Range Typical Cost (unit) Key Limitation
Fixed dome / turret, 4MP Standard external coverage High at short range £60–200 Fixed angle; coverage limited to mounting point
Bullet, 4MP, long-range IR Perimeter, long distances High at target £80–250 Visible; more vandal-vulnerable
PTZ, 2–4MP, 25× optical zoom Operator surveillance, tracking Variable (zoom dependent) £400–2,000+ Mechanical failure; expensive; can miss events
Fisheye, 12MP Room overview, 360° lobby Low at perimeter £150–500 Poor pixel density for identification at range
Box camera + external lens Specialist applications High (lens-dependent) £200–600+ Manual adjustment; no IR built-in
Thermal camera Perimeter detection in total dark N/A (heat signature) £500–5,000+ No facial identification; detection only

Detailed Guidance

Resolution — How Much Do You Need?

Camera resolution is measured in megapixels (MP) or line pairs per picture height (TVL for analogue). For identification purposes, what matters is pixels per metre at the target distance — derived from the camera's total resolution and the field of view width at that distance.

Worked example: A 4MP camera (2688×1520 pixels) with a 2.8mm lens has a horizontal field of view of approximately 98°. At a distance of 10m, the field of view width is approximately 20m. Horizontal pixel density = 2688 pixels / 20m = 134 pixels/metre. This meets the ICO/Caltech recognition threshold (100 pixels/metre). At 20m, the width is approximately 40m, and pixel density = 67 pixels/metre — observation quality only.

Selecting resolution for your application:

Application Target Pixel Density Suggested Resolution
Perimeter detection (human presence at 50m+) 25 pixels/m 4MP with 12mm lens
Vehicle entry, plate reading (at 8–15m) 100+ pixels/m 4MP with 4–8mm lens, or dedicated ANPR
Pedestrian identification (at 5–10m) 100+ pixels/m 4MP with 2.8–4mm lens
Shop floor overview (15–20m wide) 50 pixels/m minimum 8MP fisheye or 4MP with wide lens
ATM/counter close-up (<3m) 250+ pixels/m 4MP with 8mm+ lens, short mounting distance

Lens Selection

Fixed focal length lenses (most common):

Varifocal lenses:

Focal length rule of thumb for identification: If you need to identify individuals, the camera's horizontal field of view at the target distance should be no wider than 8m (for 4MP cameras). For a 4MP camera, this means:

IR and Low-Light Performance

UK outdoor lighting conditions: External cameras in the UK face significant low-light periods (winter evenings, overcast days). A camera rated at 0.01 lux in colour mode may switch to B&W IR mode even on overcast evenings in winter.

Key specifications:

White-light illumination: For colour footage at night, white-light LEDs are used. These are more effective for identification than IR (which produces B&W footage). However:

IP Rating Selection for UK Conditions

UK weather conditions include:

Minimum ratings:

Common IP rating failures in CCTV:

Wide Dynamic Range (WDR)

WDR is essential for cameras facing windows, doorways with bright exterior, or any scene with mixed bright and dark areas. Without adequate WDR, the camera adjusts exposure to the brightest area (e.g. a bright window), causing everything else in the image to appear black.

WDR is measured in dB; a higher dB value indicates a greater range of brightness the camera can handle:

True WDR vs digital WDR: Many cheaper cameras advertise WDR but use a software-only approach (DWDR) that simply boosts shadows — this does not provide the same performance as true sensor-level WDR (which captures multiple exposures and combines them). Specify "true WDR" for cameras in challenging lighting conditions.

PTZ Camera Selection

PTZ cameras are justified when:

Specify PTZ cameras by:

Frequently Asked Questions

Can I reuse existing analogue cameras on a new digital (IP) recording system?

Yes, using an analogue-to-IP bridge (AHD/TVI/CVI to IP converter) or by selecting an NVR that has hybrid inputs (accepting both IP and analogue HD cameras). However, analogue cameras are limited to approximately 5MP maximum resolution and do not benefit from most IP camera features (analytics, intelligent IR, cloud streaming). Reusing analogue cameras is cost-effective for short-term budget constraints, but in most cases full replacement with IP cameras provides much better value over a 5–10 year system life.

How many cameras do I need to cover a typical small retail unit?

A typical small retail unit (100–200m² floor area) usually needs 4–6 cameras:

For a layout plan, sketch the floor plan and mark zones: entrance, till, stock room access, areas of highest loss risk. Cover those zones with the minimum number of cameras that provides the required resolution. Avoid over-specifying (cameras pointing at empty walls or the ceiling) — it adds cost without security benefit.

What is the minimum specification for a system that satisfies most commercial insurers?

For a basic commercial property, most insurers require:

Check the specific insurer's requirements — they vary. Some specify exact camera resolution, retention period, or monitoring requirements. Always advise the customer to check their insurance documentation before commissioning the system.

Regulations & Standards