What is the difference between horizontal and vertical field of view?

Horizontal FOV is the width of the scene captured (left to right), while vertical FOV is the height (top to bottom). A 2.8mm lens typically gives ~110 horizontal and ~60 vertical FOV.

Does higher resolution change the field of view?

No, resolution does not change FOV -- that is determined by lens focal length and sensor size. However, higher resolution means more pixels across the same FOV, allowing you to see finer details at distance within that view.

What FOV do I need for facial recognition?

For reliable facial identification you need at least 250 pixels per meter (PPM) on the subject's face, the threshold defined in EN 62676-4. With a 4MP camera and 2.8mm lens this means subjects must be within roughly 5–7 meters of the camera. Beyond that distance, switch to a longer focal length (4–6mm) or a higher-resolution camera (8MP+).

How does FOV change with camera mounting height?

The angular FOV stays constant — only the ground area covered changes. Higher mounting captures more area but requires more downward tilt, which reduces effective horizontal reach. For most indoor surveillance a 2.7–3.5 m mounting height with a 15–30° tilt gives the best balance of near and far coverage.

What is the difference between FOV and DORI distance?

FOV is the angle of view in degrees — how wide the camera sees. DORI (Detection, Observation, Recognition, Identification) is the distance at which the camera meets pixel-density thresholds defined in EN 62676-4: 25 PPM for detection, 63 for observation, 125 for recognition, and 250 for identification. Two cameras with identical FOV can have very different DORI distances depending on resolution and sensor size.

Can I use a 2.8mm wide-angle lens for everything?

No. A 2.8mm lens gives roughly 110° horizontal FOV — excellent for wide rooms, entrances, and short distances. But subjects beyond ~6 meters become too small for identification. For long corridors, parking lots, or perimeter coverage use 4–8mm (general) or 12–25mm (long distance) lenses.

CCTV Field of View Explained: Lens Chart + DORI Guide [2026]

What is Field of View (FOV)?

Field of View is the angular extent of what a camera can see. Measured in degrees, FOV determines whether a lens is wide-angle, standard, or telephoto. A 2.8mm lens on a 1/3" sensor has a ~110° horizontal FOV, while a 50mm lens on the same sensor has only ~5.7° FOV.

Key Points:

Wider FOV: Shows more area but with less detail
Narrower FOV: Shows less area but with more detail (zoom effect)
Affected by: Focal length, sensor size, and distance

How Field of View Works

FOV is calculated using trigonometry. The light rays entering the camera lens form a cone shape. The angle at the tip of this cone is your field of view. A wider lens creates a wider cone; a narrower lens creates a tighter cone.

Think of it like a person standing in a room: if you face straight ahead with eyes forward, your FOV is narrow. If you turn your head and use peripheral vision, your FOV widens. A camera lens works the same way.

Focal Length Explained

Focal length is the distance (in millimeters) from the lens's optical center to the camera's sensor. Shorter focal lengths (2.8mm, 3.6mm) produce wider fields of view. Longer focal lengths (25mm, 50mm) produce narrower, more zoomed-in fields of view.

Focal Length	FOV Category	Typical Use
2.8-3.6mm	Wide Angle 90+ deg	Wide area coverage, retail
4-8mm	Standard 45-90 deg	General coverage
12-25mm	Telephoto 15-45 deg	Long-distance, identification
35-50mm	Very Telephoto less than 15 deg	Extreme zoom, license plates

How Sensor Size Affects FOV

Sensor size significantly impacts field of view. A 2.8mm lens on a 1/2" sensor (6.4mm wide) produces a wider FOV than the same lens on a 1/3" sensor (4.8mm wide). Larger sensors capture a wider angle for the same focal length.

This is why smaller sensors (1/3") are commonly used in security cameras—they enable wider coverage with shorter, cheaper lenses. Larger sensors (2/3", 1") are used when depth of field or low-light performance is critical.

Practical FOV Examples

Example 1: Retail Store Entrance

To cover a 20-foot wide store entrance from 10 feet away, you'd want a ~110° FOV. Using a 1/3" sensor, a 2.8mm lens provides exactly this. This allows facial recognition of entering customers.

Example 2: Parking Lot Perimeter

Monitoring a parking lot from a pole requires seeing 100+ feet. A telephoto 25mm lens on a 1/3" sensor provides ~15° FOV, allowing detailed license plate capture.

Example 3: Warehouse Corner

Monitoring a warehouse corner from ceiling height, a 3.6mm lens on 1/3" sensor provides ~90° FOV, covering aisles and preventing blind spots.

How to Calculate FOV

FOV is calculated using trigonometry:

FOV = 2 × arctan(sensor_width / (2 × focal_length)) × (180 / π)

Where sensor_width is in mm and focal_length is in mm

For example, with a 1/3" sensor (4.8mm width) and 3.6mm lens:

FOV = 2 × arctan(4.8 / (2 × 3.6)) × (180 / π) = 73°

Use our interactive FOV calculator to determine exact FOV for any sensor and focal length combination.

CCTV Field of View Explained: Complete Guide for 2026

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