CCTV Lens Calculator
Find the focal length for your mounting distance and preview what the camera records
Setting
Detail you needA check mark means these specs can do it
What the camera records (illustration)
Can recognize
The picture and distances are illustrative — see how they are worked out below
Focal lengthWidth at the target’s distance
Resolution
HiLook+ models with these specs (12)
Field of view
- Scene width at 6 m
- 11.0 m
- Detect
- 41.9 m
- Observe
- 16.8 m
- Recognize
- 8.4 m
- Identify
- 4.2 m
2.8mm, 4mm or 6mm — which should I choose?
A shorter focal length gives a wider view and covers more area, but each person gets fewer pixels, so faces are only identifiable closer to the camera. A longer focal length is the opposite: it sees further across a narrower area.
Where you need to see faces — doorways, corridors, counters — use a longer focal length aimed at a spot everyone passes through. Where you need coverage — car parks, yards — use a 2.8mm wide angle. If one spot needs both, two cameras splitting the job usually work better than one trying to do everything.
What is DORI?
DORI is a set of four levels defined in the international standard IEC 62676-4. Each level is set by how many pixels the target gets per meter (px/m). Pixel density is the horizontal resolution divided by the scene width at that distance, so a higher resolution or a longer focal length pushes every level further out. This tool applies that same method to every camera, so different brands can be compared side by side.
| Level | What the footage shows | Pixel density |
|---|---|---|
| Detection | Tell that a person or vehicle is present | 25 px/m |
| Observation | Make out movements and characteristic details such as clothing color | 62.5 px/m |
| Recognition | Tell whether the person is someone you know | 125 px/m |
| Identification | Establish a stranger’s identity; footage can serve as evidence | 250 px/m |
Datasheet DORI distances are usually measured at the frame center under ideal conditions and run about a third longer than the frame average — compare brands using the same method.
How are the picture and distances worked out?
The picture is an illustration: the camera is mounted about 2.8 m up (indoors, on the ceiling) or 4.5 m up (outdoors, on a pole) and looks down, with perspective from the resolution and field of view; lens distortion, compression, noise and night imaging are not modeled. The main picture is shrunk to fit your screen, as on a monitor; the zoom inset works like a recorder's digital zoom and shows the detail actually recorded.
Distances use the IEC 62676-4 pixel-density thresholds, computed from resolution and horizontal field of view as an average across the frame, which is conservative; datasheet DORI figures are usually measured at the frame center under ideal conditions and run longer. At night the infrared or supplemental light range also applies — check the night-vision range on the product page.
Need more help?
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