What is Field of View: Understanding the Basics

Visual experiences play significant roles in daily life thanks to the rapid development of different digital devices. Whether through the lens of a camera, the eye of a microscope, or the immersive screens of our favorite video games, the concept of "Field of View (FoV)" dramatically impacts how people see the world. This article will help you understand the FOV meaning, its practical applications, and how it can significantly impact the performance and coverage of your security cameras.

What is the FOV Meaning?

The field of view (FOV) refers to the extent of the observable world or scene that can be seen at a given moment through a particular device, such as a camera, microscope, binoculars, or the human eye. It defines the area or angle visible within the observation frame. In the case of optical devices, FoV is the maximum area that the device can capture. The broader the FOV, the more people can see, whether they're looking through a camera lens or at a screen.

Applications of Field of View

The term "Field of View (FOV)" can be found in many optical devices and used in multiple scenarios. Here are some practical applications of this concept.

In Photography and Videography

In photography and videography, the field of view is the angular extent of the observable scene that a lens or a camera can capture. It's often expressed in degrees or radians. A wider field of view means that more of the set is visible, useful for capturing landscapes or large groups of people. A narrower field of view is often used for telephoto shots or when photographers or video directors want to focus on a more minor subject.

In Astronomy

Astronomy enthusiasts and scientists often use telescopes or binoculars to observe the infinite sky. For astronomical devices, the field of view describes the area of the sky that can be observed through a telescope or binoculars. It is often measured in degrees, and a larger field of view allows for a broader view of celestial objects. A narrower field of view helps focus on specific astronomical objects.

In Security Camera

The field of view determines the area or angle that the camera can capture and monitor. The special FOV of security cameras can vary from one model to another. Some security cameras may have fixed lenses, which provide a constant FOV, while varifocal cameras can zoom in or out to change the FoV according to the user's needs.

Furthermore, some security cameras are designed with a wide-angle lens and have a broader FOV suitable for monitoring large areas, like parking lots or open spaces. Others have narrower lenses that are ideal for focusing on specific targets or areas in greater detail.

For example, the Reolink TrackMix series combines a telephoto and wide-angle lens to provide comprehensive coverage, allowing users to view close-up and wide-angle perspectives simultaneously. This series offers various models, including WiFi, PoE, 4G, and battery-powered options. The TrackMix WiFi supports dual-band 2.4/5GHz WiFi and integrates seamlessly with Reolink NVR systems.

In Microscope

In microscopy, the field of view refers to the area visible through the microscope's eyepiece or on a digital display. The field of view can vary depending on the objective lens used, with higher magnification objectives typically having a smaller field of view.

In Gaming

For video games and virtual reality (VR) experience, the field of view is the extent of the in-game environment that can be seen on the screen. Some of these parameters can be adjusted to affect the perception of speed, realism, and the player's spatial awareness. A wider FOV can give a more immersive feeling but might require more computing power to render.

How to Calculate Field of View

The field of view of a camera or optical instrument depends on the focal length of the lens or eyepiece, the sensor size (for digital cameras), and the distance between the lens or eyepiece and the object of interest. Here is a simplified formula:

FOV= (Sensor Dimension / Focal Length) x 57.3

There are several main elements in this formula:

FOV: the field of view of an optical instrument in degrees.
Sensor dimension: the size of the digital camera image sensor, typically measured in millimeters.
Focal length: the distance from the lens to the point where parallel rays of light converge when they pass through the lens.
57.3: used to convert radians to degrees.

Note: If you want to calculate the FOV of your device, you can search for some online FOV calculators.

Factors Affecting Field of View

Several factors can affect the optical instrument's field of view. Depending on various factors, users can strategically choose the correct FOV for different applications.

Lens Focal Length

The focal length of a camera lens can affect the field of view because it determines how light rays are refracted and focused onto the image sensor (or film plane) within the camera. When light rays pass through a lens, their paths are bent due to their curved shape. These rays can either converge or diverge. The extent to which they converge or diverge depends on the curvature of the lens.

Lenses with short focal lengths have more curved shapes and cause light rays to converge more quickly. As a result, they bring distant objects into focus and capture a wider area within the camera's FOV. In contrast, lenses with long focal lengths have flatter or less curved shapes and cause light rays to converge more slowly. As a result, long focal length lenses capture a narrower FOV.

Image Sensor Size

The size of the image sensor directly affects how the camera captures and records the light coming through the lens, which in turn impacts the FOV. Large image sensors will allow more light to pass through than smaller sensors. Smaller sensors tend to result in a narrower FOV and can magnify the image, while larger sensors provide a wider FOV.

Sensor Aspect Ratio

The sensor aspect ratio is the sensor's width-to-height ratio. The sensor aspect ratio can affect the field of view (FOV) and the composition of an image by determining how much of the scene is captured horizontally and vertically, especially when using lenses designed for a specific aspect ratio. A camera with a 3:2 or 16:9 aspect ratio captures a slightly wider FOV than a 4:3 aspect ratio.

Camera Orientation

The camera orientation can also influence the field of view. When you change the camera's direction from landscape (horizontal) to portrait (vertical) or vice versa, it alters the FOV and the image's composition. In landscape orientation, the FOV is typically broader and suitable for capturing wide scenes. In portrait orientation, the FOV is narrower, which can help focus on a taller subject or emphasize vertical elements in the frame.

Tilting the camera up or down (pitch) and panning it left or right (yaw) also affects the FOV. Tilted upward, the FOV may emphasize the sky or tall objects, while tilting downward highlights the ground or low objects.

Distance to Subject

The distance to the subject can affect the perceived field of view (FOV), but it doesn't directly alter the physical FOV of the camera or lens. Instead, it influences the composition and perspective of the image. If you move closer to the subject, you may need to use a wider-angle lens to encompass the subject within the frame, making the FOV appear wider. Conversely, if you move farther from the subject, you might need to use a longer focal length lens (telephoto) to frame the subject as desired, making the FOV appear narrower.

Lens Aperture

Lens aperture doesn't directly affect the field of view, but it will change the composition of different images. The lens aperture significantly affects the depth of field, which is the range of distances in the scene that appears acceptably sharp in the picture. A wider aperture (e.g., a lower f-number like f/1.8) will result in a shallower depth of field. This depth of field usually makes the background and foreground more out of focus. The image appears to have a narrower FOV, even though the FOV itself remains the same.

Field of View in Security Cameras: Selection and Placement

Selecting the appropriate field of view for security cameras is essential for an effective surveillance system. So why is the field of view so crucial for security camera selection? This part may give you the answer.

Importance of FoV in Security Camera Selection

Here are some reasons why the field of view matters to security cameras.

• Coverage and Monitoring Range: The field of view determines the range the security camera can cover and monitor. Generally speaking, the wider the FoV, the more space the camera can cover. To ensure that all the essential areas are within the camera's monitoring range, you should carefully choose the right FOV. A wider field of view can also help minimize blind spots and provide comprehensive coverage.
• Identification and Recognition: The field of view can also influence the camera's ability to identify and recognize individuals or objects in the footage. A narrower field of view can increase the details captured in one picture. You can also choose a camera that combines a more limited field of view and a higher resolution. This camera may provide more details on specific subjects, such as facial features or license plates.
• Event Capturing: The appropriate field of view can accurately capture essential events within the monitoring area. Whether it's a security breach, an accident, or any other critical incident, the camera must have a proper FoV to capture the relevant details.
• Cost-Effective Security Solution: Selecting the right field of view can also help you reduce costs on daily surveillance. If you choose a wider field of view, the camera may cover a wide range, reducing the number of cameras required for surveillance. An appropriate field of view can lead to cost savings regarding equipment and installation, as fewer cameras are needed to cover the same area effectively.

How to Optimize Field of View Through Strategic Camera Placement

If you've chosen a particular field of view, you can place the device strategically to optimize its effectiveness. Here are some placement tips you can follow.

1. Map out camera locations: The first thing you can do is plan for the placement of each camera. If you have multiple cameras installed on site, you can create a detailed map or layout of the area and mark where you want to place the cameras.
2. Elevate the camera to certain heights: Mounting cameras at the optimal height can make the most of the field of view of your camera. You can choose to place the camera slightly higher and avoid possible obstructions.
3. Overlap coverage: If you have multiple devices inside one surveillance system, consider planning for some overlap in the range between cameras. Overlapping FoV can help eliminate blind spots and ensure continuous monitoring, especially in critical areas.
4. Determine the right viewing angle: You should check the device's viewing angle before installing. Calculate the viewing angles for each camera based on their lens specifications. Ensure that the cameras are positioned to cover the required FoV effectively.
5. Cover critical areas: You can consider installing cameras in essential places inside your home or business scenarios. For example, you can mount a camera at entry or exit points to safeguard your property.

Field of View vs. Depth of View: What's the Difference

The main difference between the field of view and depth of view is that the field of view is about the extent of what is seen, while DoV is about the range of distances at which objects appear in focus within that scene.

The depth of field refers to the range of distances within a scene that appears acceptably sharp in an image. It is about the zone of focus where objects near and far from the camera are rendered in sharp detail. In simple terms, DoF is all about what is in focus within the image. DoF is not measured in degrees but is typically quantified regarding near and far distances from the camera (e.g., feet or meters).

FAQs

What is the field of view on a camera?

The field of view of a security camera refers to the area or angle that the camera can capture and monitor. It is measured in degrees vertically and horizontally. The wider the field of view, the larger the area the camera can capture.

How can I select the best field of view?

It would help if you determined what you intend to capture with the camera. Different purposes may require distinct FOV. For example, if you are looking for a security camera, you need to map out the places you want to monitor and choose between a wide FOV (larger space) or a narrow FOV (rich details).

What is the maximum human field of vision?

The maximum human field of vision, also known as the human visual field, is approximately 200 degrees horizontally and about 135 degrees vertically. This field of vision can vary slightly from person to person due to factors like genetics and individual differences in eye anatomy.

Conclusion

The term "field of view" can be found in different scenarios. This parameter has become a fundamental element for enhanced visual experience, from photography and videography to surveillance and immersive technologies. With the knowledge gained from this article, we truly hope you can harness the power of the field of view in the future!

After reading this, do you understand the FOV meaning? Is it important? Let us know your thoughts in the comment section below, and share this article with your family and friends if you find it useful!