What Is Field of View (FoV)? Explained for Camera Modules and Lenses

When you use a camera to take pictures or a camera module to monitor, navigate, or detect, you are actually only seeing part of the world. The specific area that the camera can capture is called the Field of View (FoV) in optical terms.

The Field of View is a fundamental characteristic of camera modules and lenses, which directly determines how much of the scene your device can "see". Understanding what the Field of View is and what factors affect it is crucial to choosing the right camera module for your application.

what is fov?definition for field (FoV) refers to the spatial or angular extent of a scene that can be observed through an optical device (such as a camera lens). It defines the breadth of the world that a camera can capture at any given moment.

Think of it like looking out a window: the bigger the window, or the closer you are to it, the more you can see. The camera field of view is the angular size of the outside world that this "window" can frame. It is usually measured in degrees (°).

what is field of view2

Although sometimes also called "angle of view", in many practical applications, the two are often used interchangeably to represent the range of scenes that a camera can capture.

The field of view of a camera module is primarily determined by two key factors: lens focal length and image sensor size.

The focal length of the lens is the most important factor affecting the field of view. Focal length can be simply understood as the distance that light converges on the image sensor after passing through the lens to form a clear image.

Shorter focal length = larger (wider) field of view. Just like looking out through a very wide door crack, although not much light comes in, you can see a wide horizontal range. For example, a fisheye lens (extremely short focal length) has a very wide field of view (even more than 180°).
Longer focal length = smaller (narrower) field of view. Just like looking through a telescope, you can only see a small range in the distance, but this range is magnified. For example, a telephoto lens (long focal length) has a very narrow field of view. This relationship is inversely proportional: the longer the focal length, the narrower the camera field of view; the shorter the focal length, the wider the field of view.

Even with the same focal length lens, different image sensor sizes affect the resulting field of view. The lens projects the light from the scene into a circular image area (called the "image field"), and the image sensor is located in this image field.Article about What is a Sensor.

Larger sensor size = larger field of view (when using the same focal length lens). Just like using a large picture frame to capture a fixed-size painting, the larger the picture frame, the more of the painting is captured. A large sensor can capture a larger part of the image field projected by the lens.
Smaller sensor size = smaller field of view (when using the same focal length lens). Small sensors can only capture a smaller area in the center of the image field. This relationship is proportional: the larger the sensor size, the wider the field of view.

Therefore, the field of view of a camera module is the result of the interaction between the focal length of the lens and the size of the image sensor. The same lens, mounted on sensors of different sizes, has different camera field of view. This is why a 50mm lens on a full-frame camera (large sensor) will produce a "wider" image than a 50mm lens on an APS-C camera (small sensor) (there is a "crop factor" effect on the small sensor).

The field of view is usually expressed in degrees (°). For a more precise description, the field of view can be divided into:

Horizontal field of view (Horizontal FoV): The angle range included in the left and right directions of the image.
Vertical field of view (Vertical FoV): The angle range included in the top and bottom directions of the image.
Diagonal field of view (Diagonal FoV): The angle range included in the diagonal direction of the image, usually the largest angle.

In the specification of the camera module, one or more field of view values in horizontal, vertical or diagonal directions are usually given. The field of view can be calculated by simple trigonometric formulas (involving focal length and sensor size), but in most cases, manufacturers will provide these specifications directly.

how to measure fov0

According to the size of the field of view, we can roughly divide lenses or camera modules into several categories:

Wide-Angle FoV: Usually refers to a camera field of view greater than 60° or even 90°. It can capture a very large range of scenes and is suitable for shooting landscapes, buildings, imaging in small spaces, or monitoring that requires wide coverage. Ultra-wide-angle and fisheye lenses (which may exceed 180°) belong to this category.
Standard/Normal FoV: Usually between 40° and 60°. This range of field of view is close to the clear range that the human eye sees without moving the eyeball, and is often used for portraits or ordinary recording.
Telephoto FoV: Usually less than 30°. It can capture a smaller range in a distant scene and magnify it, which is suitable for shooting wildlife, sports events, long-distance monitoring, or industrial inspections that need to magnify details.

The field of view is one of the key parameters that must be determined first when selecting a camera module, because it is directly related to whether the module can meet the basic requirements of the application:

Application scenarios determine FoV:

If your vision system needs to monitor a spacious room or an autonomous vehicle needs to perceive the wide road ahead, you need a module with a wide-angle field of view.
If your system needs to read distant text, identify distant objects, or check details without getting close, you need a module with a telephoto field of view.
If the camera module will be used for indoor robot navigation, it needs to take into account both environmental perception and obstacle avoidance, and may require a medium to wide field of view.

Article about How to Choose Camera Module for Vision System.

Fundamentals of lens selection: Once the desired FoV and sensor size to be used are determined, the appropriate lens can be selected or designed based on these parameters.

System design considerations: The desired FOV affects the location, height, and angle of the camera module in the overall system, and whether multiple modules are required to cover the target area.

Field of View (FoV) is an angular measurement of the range of scenes that a camera module and lens can "see". It is mainly determined by the focal length of the lens and the size of the image sensor it is paired with. The shorter the focal length and the larger the sensor, the wider the FOV.

Understanding what FOV is and determining the required FOV based on your specific application requirements is the basis for successful camera module selection and system design. From monitoring large areas to focusing on distant details, the right FOV ensures that your camera module can capture all the visual information needed to solve the problem.

1.What is the relationship between Field of View (FoV) and Zoom?

A.Zoom refers to the ability to change the angle of view by changing the focal length of the lens. A zoom lens allows the focal length to be adjusted within a certain range, thereby changing the magnification and field of view of the image (longer focal length, narrower field of view, and larger image; shorter focal length, wider field of view, and smaller image). Fixed focal length lenses have a fixed field of view and cannot be zoomed.

2.Is the field of view of the camera module fixed?

A.For camera modules using fixed focal length lenses, the field of view is fixed (determined by the lens focal length and sensor size). If a zoom lens module is used, the field of view can be changed by adjusting the focal length within the zoom range. In addition, digital zoom (Digital Zoom) through software is to enlarge part of the picture, but this does not change the actual field of view, but only crops the image, which will lose details.

3.Will different field of view angles affect image distortion?

A.Yes, especially wide-angle lenses, in order to capture a wider range, the optical design is more prone to image distortion, such as "barrel distortion" (the edges of the image bend outward, common in fisheye lenses). Telephoto lenses usually have better distortion control. In vision systems that require precise measurement, if wide-angle lenses are used, distortion correction is usually required.

One-stop camera module customization solution

Send us your requirements for camera modules and we will customize the best solution for you. With our premium solutions, you can enhance your products, engage your customers, and open new opportunities for the growth and success of embedded vision applications.

Send Inquiry Now