4mm Tiêu chuẩn

Góc nhìn ngang 61.9° - Hướng dẫn tham khảo phủ sóng đầy đủ

Tiêu cự

4mm

Góc nhìn

61.9°

Loại Ống kính

Tiêu chuẩn

Cảm biến

1/3"

About the 4mm lens

A 4mm lens provides about 70° horizontal field of view — close to what a person sees when scanning a scene without turning their head. This makes it the most "natural" CCTV focal length and the default choice for general-purpose installations where you want a balance of coverage area and identification distance.

Best for

•General building monitoring across rooms, corridors, and small open spaces
•Residential driveways, gardens, and back yards where typical recognition distances are 5–12 m
•Shop entrances, cash registers, and POS-area surveillance
•Standard parking spaces (covering 2–3 spots from a single mount)

Trade-offs

•Coverage is moderate — for a 10m wide area, the camera must be mounted roughly 7m back
•Faces remain identifiable up to about 10 meters in good light, dropping fast beyond that
•Less suited to corner-to-corner room coverage than 2.8mm or 3.6mm options

Real-world example

A 4mm lens at 3 m mounting height covers a 4 m wide area immediately below and identification of faces remains good up to roughly 10 m away. Most NVR vendors quote "coverage" specs assuming 4mm focal length — when you see "covers up to 12m identification" in marketing materials, that figure typically assumes a 4mm lens on a 1/3" sensor.

Compared to other focal lengths

4mm is the benchmark against which other lenses are measured. Going wider (3.6/2.8mm) trades distance for area; going longer (6/8/12mm) trades area for distance. Most multi-camera installations use a mix of 4mm for general coverage and 6–8mm for chokepoints.

Chiều rộng Phủ sóng ở Các Khoảng cách

Khoảng cách	Chiều rộng Phủ sóng	Ứng dụng
5m	6.0m	Lối vào/Khu vực POS
10m	12.0m	Sàn bán lẻ, văn phòng
15m	18.0m	Lối đi nhà kho, bãi đỗ
20m	24.0m	Lối đi nhà kho, bãi đỗ
30m	36.0m	Bãi đỗ xe, chu vi
50m	60.0m	Bãi đỗ xe, chu vi
75m	90.0m	Giám sát khoảng cách xa
100m	120.0m	Giám sát khoảng cách xa