Horizontal field-of-view estimator
Measure the width you need to cover at the target distance, then compare the exact camera’s horizontal field of view. A focal length such as 2.8 mm does not specify the same view on every sensor. Separate a wide overview from a view intended to show a face or handover.
Choose the lens for its viewing task
| Lens choice | Useful task | Check |
|---|---|---|
| Fixed | A known entrance or room view. | Exact horizontal angle and target detail at the installed distance. |
| Varifocal | Adjust the width during commissioning. | Adjustment range, focus and whether adjustment is manual or motorised. |
| Optical zoom | Capture a narrower view through the lens. | Detail and focus throughout the stated optical range. |
| Digital zoom | Enlarge part of an existing image. | It cannot recover detail absent from the original recording. |
Estimate the width, then check the recording
For a rectilinear lens on level geometry, scene width is approximately 2 × distance × tan(horizontal angle ÷ 2). At 5 m and 90°, this gives 10 m. A 2,560-pixel-wide stream across that width averages 256 pixels/m. These are geometry examples; distortion, viewing angle, compression and light change useful detail. This is not an identification-distance claim.
- Record mounting height, target distance and required width.
- Compare the published horizontal angle for the exact sensor and lens.
- Place a moving subject at the near and far positions; check obstruction, focus and glare.
- Review recorded and exported clips in daylight and after dark before accepting the lens.
Considering the 605GP PoE camera option? Include target distance, required width and mounting height in the request. Confirm the exact variant’s horizontal angle and recorded night detail before accepting the view.
Zoom and dual-lens ordering checks
A zoom ratio compares focal-length endpoints; it does not specify an identification distance. Hybrid zoom may combine optical and digital methods. For dual-lens equipment, ask which view is saved, its individual stream resolution, and how zoom and camera control work with the selected recorder. Keep fixed-focal-length comparison and PTZ operation as separate decisions.
Technical background: Axis: lenses in surveillance. The principles do not establish specifications for a QuarkView model. Request a lens configuration with distance, required width, mounting height and day/night viewing task.