What is Machine Vision Field of View (FOV)?

In the field of industrial imaging, the Field of View (FOV) is the physical area of the object under inspection that is visible to the camera sensor. Calculating the FOV is one of the most critical steps in designing a machine vision system. It ensures that the specific features you need to inspect—whether they are tiny defects on a PCB or barcodes on a shipping pallet—are fully captured by the camera sensor with sufficient resolution.

How to Calculate FOV

The relationship between the lens, the sensor, and the object is governed by optical geometry. The basic formula for calculating the Field of View is: FOV = (Sensor Size × Working Distance) / Focal Length.

To use this calculator effectively, you must provide three primary variables:

• Sensor Size: The physical dimensions (width and height) of the imaging sensor, typically measured in millimeters.
• Focal Length: The fixed property of your lens (e.g., 8mm, 16mm, 25mm, 50mm).
• Working Distance: The distance from the front of the lens to the object being inspected.

Understanding the Parameters

Working Distance (WD): Often, the working distance is constrained by the physical environment, such as the height of a conveyor or the space inside a robotic cell. If your WD is fixed, you must select the correct focal length lens to achieve the desired FOV.

Focal Length: A shorter focal length (e.g., 6mm) provides a wider field of view but may introduce more optical distortion. A longer focal length (e.g., 50mm) provides a narrower, "zoomed-in" view, which is often better for precision measurements.

Sensor Format: Different cameras use different sensor sizes. A 2/3" sensor is larger than a 1/3" sensor and will provide a wider FOV using the exact same lens and working distance.

Frequently Asked Questions

Why is my calculated FOV different from the actual image?

Calculations provide a theoretical value. Real-world results may vary slightly due to lens distortion, manufacturing tolerances, and the fact that the focal length of a lens is usually measured when focused at infinity.

How do I increase my Field of View?

To increase the FOV, you can either increase the Working Distance (move the camera further away) or use a lens with a shorter Focal Length (wide-angle lens).