Related tools
Calculate field of view or check pixels per meter.
Related guide: CCTV Lens & Field of View Guide →
How CCTV Lens Focal Length Is Estimated
The calculator uses sensor width multiplied by distance, divided by desired scene width.
2.8mm vs 4mm vs 6mm Lens
Shorter focal lengths usually provide wider coverage, while longer focal lengths usually provide tighter coverage.
Fixed vs Varifocal Lens
Fixed lenses have one focal length. Varifocal lenses can be adjusted across a range for more installation flexibility.
Sensor Size and Lens Selection
Sensor dimensions affect the focal length needed for a target scene width.
Lens Distortion and Real Camera FOV
Datasheet values should be checked because lens distortion and camera processing can change actual FOV.
Example CCTV Lens Calculation
A 5.6 mm sensor width at 10 m distance needing a 10 m scene width gives an estimated 5.6 mm focal length.
FAQ
What CCTV lens do I need?
Start with desired scene width, distance, and actual sensor size, then verify compatibility and published FOV.
Is 2.8mm wider than 4mm?
Generally yes for the same sensor size, but actual FOV depends on lens and camera design.
What is a 6mm CCTV lens used for?
Usually a tighter view than common 2.8 mm or 4 mm lenses, useful when the target area is narrower or farther away.
Does sensor size change the required focal length?
Yes. Sensor width directly affects the estimated focal length.
What is a varifocal lens?
A lens with an adjustable focal length range.
Can I calculate exact FOV from focal length alone?
No. Sensor size and lens design are also required.
Why should I check the camera datasheet?
Lens mount, image circle, distortion, focus, iris, and manufacturer implementation affect compatibility.