The difference lies in what is measured: Angle of View is the angle that determines what is seen, while Field of View is the actual physical area or dimension that is visible.
Understanding the distinction between Field of View (FOV) and Angle of View is fundamental, particularly in optics, photography, and vision systems. While often used interchangeably in casual conversation, they describe related but distinct concepts.
Field of View (FOV)
As stated in the reference, Field of View (FOV) refers to the actual dimensions of the full frame. It describes the extent of the observable world that is seen at any given moment.
- What it is: The physical size or dimension of the scene captured or viewed.
- How it's measured: Typically measured as a length or width (often specifically on the horizontal plane) at a certain distance from the observer or lens, or sometimes described as an area. The reference explicitly states it's measured as a length on the horizontal plane of the frame.
- Think of it: The actual amount of landscape you see edge-to-edge in a photo or through binoculars.
Angle of View
The reference clarifies that Angle of view refers to the angle that the lens allows in light, which dictates the field of view. It is an angular measurement.
- What it is: The angular extent of a given scene captured by a camera or visible to an observer.
- How it's measured: Measured as an angle, typically in degrees (e.g., horizontal, vertical, or diagonal angle).
- Think of it: The "wideness" or "narrowness" of the perspective captured by a lens.
Key Differences Summarized
Based on the provided reference and general understanding:
- Nature: Angle of View is an angle; Field of View is a dimension (length/width or area).
- Relationship: Angle of View dictates or determines the Field of View. The wider the angle of view (with the same distance), the larger the field of view.
- Measurement: Angle of View is measured in degrees; Field of View is measured in length (e.g., meters, feet) or sometimes area, depending on the context and distance.
Comparison Table
| Feature | Angle of View | Field of View (FOV) |
|---|---|---|
| What it is | An angle capturing the scene | The physical dimension/area of the scene seen |
| Measurement | Degrees | Length (e.g., meters, feet) or Area |
| Relationship | Dictates the Field of View | Is determined by the Angle of View (and distance) |
| Reference | Angle lens allows light in | Actual dimensions (length on horizontal plane) |
Practical Insight
The focal length of a lens is the primary factor determining the Angle of View. A shorter focal length (like a wide-angle lens) has a wider angle of view, which results in a larger Field of View (more of the scene is captured). A longer focal length (like a telephoto lens) has a narrower angle of view, resulting in a smaller Field of View (less of the scene is captured, making distant objects appear closer).
Understanding both concepts is crucial for selecting the right lens for a specific shot or configuring vision systems to cover the desired area.
