CCTV lens calculator
Spec the lens before you go up the ladder. Focal length, sensor and resolution in; FoV, scene width and px/m at target distance out, checked against the DORI thresholds.
Field of view
85°
horizontal angle
Scene width at 10m
18.2 m
what the frame covers
Detail level
141 ppm
Recognise: known faces, number plates
| DORI level | Needs | This setup |
|---|---|---|
| Identify | ≥ 250 ppm | up to ~5.6 m |
| Recognise | ≥ 125 ppm | Yes |
| Observe | ≥ 62 ppm | Yes |
| Detect | ≥ 25 ppm | Yes |
Stock cameras at 2.8 mm
- 2.8 mm fixedVIPER PRO 5MP 3K Camera - 24-Hour Smart Light CCTVAvailable
- 2.8 mm fixed5MP AI IP Dome Camera PoE Face Detection IR Night Vision 256GB SD ONVIF IP67Available
Figures assume the sensor selected above; check the real sensor size on the product page. Same focal length, wider sensor: wider view.
Reading the numbers
Wide (2.8mm) covers plenty and identifies little; tight (12mm) identifies at range through a narrow window. DORI (IEC 62676-4) puts figures on it, all in px/m: 250 for positive ID on a stranger, 125 for a known face or a number plate, 62 to observe the event, 25 to detect movement.
Standard approach on a job: wide lens on the door for context, tighter lens or higher-res camera on the approach where you need the ID. If one camera has to cover both, fit a varifocal and set the compromise on site.