As a passionate photographer or astronomer, we are sure you stumbled across a wide array of technical terms that seemed impossible to learn at the beginning. And if you weren’t good at math or physics in high school either, some of these terms might have caused headaches and insomnias.
One of these concepts is the field of view, which you’ll find online described as the extent of the world that can be observed at any given moment. When we refer to the human vision, the field of view is commonly considered a restriction to what is visible by external devices, similar to wearing a pair of virtual reality goggles. The natural eye movement is allowed in defining the field of view, but it won’t alter it.
In the following lines, we will try to describe the process behind it as best as possible, as well as bring you some interesting facts about the concept.
What is the visual field in humans and animals
The corresponding concept in animal vision (including humans) of the field of view is the visual field, which, according to an online definition, represents “the number of degrees of visual angle during a stable fixation of the eyes”. However, this definition excludes the eye movements that can differ from one species to another.
So exactly how much can one bird or animal see? The range of visual abilities depends on various factors, including the positioning of the eyes which differs from one animal to another.
In general, humans have a roughly 210-degree forward-facing horizontal arc of the visual field, while some birds can reach nearly full 360-degree. The same goes for certain frogs and reptiles such as chameleons that have a wide arc of their visual field due to their eye position.
Certain studies even link the diet of an animal to its ability to see forward or sideways. Thus, most predator animals have a bigger forward-facing arc of their visual field as they mainly focus on chasing the prey, while herbivorous animals count on an improved peripheral sight since they have to see potential threats and predators from far away.
By comparison, a regular pair of hunting binoculars doesn’t cover more than 114 degrees horizontally.
Why is the field of view important?
Calculating the field of view is important in industries like astronomy, photography, video games or virtual realities, as well as in medicine when dealing with microscopes.
In photography, the concept represents the part of the world visible through the camera at a given spatial orientation and position. Objects that are located outside the field of view (FOV) when the photo is taken are not recorded in the final image.
However, it is mainly expressed as an angle of view (AOV) rather than a FOV. There is a difference between these two that is quite difficult to explain to those without a solid knowledge of math, physics, optics, and photography.
One article claims that while both AOV and FOV are expressed in angles, these two notions are different. The AOV represents a property of the lens and won’t change regardless of the sensor size inside the camera, while the FOV depends on the lens and the size of the sensor.
In astronomy, you’ll most likely find the field of view expressed in square degrees or square arc-minutes for the higher magnification instruments. Not even a high-performance and fully computerized telescope will be able to provide a full angle of view of the skies, which is why it is impossible for us to count the stars or realize the true greatness of the universe.
A regular pair of astronomy binoculars won’t do the sky justice either. Therefore, we are yet to develop and manufacture high-precision tools that will give us a clearer image of the sky, the stars, and the planets in our Solar System.
The field of view is an essential characteristic of video games, whether we’re talking about console ones, computer video games or, more recently, smartphone games. The field of vision differs from one game to another, depending on the category we are talking about. Shooter games or first-person ones usually measure the FOV as a human would see it.
Therefore, the observable game world at any moment is measured by an angle, but the type of angle we are talking about (whether horizontal, diagonal or vertical) depends on the game developer and varies. When referring to video games, the FOV also depends on the aspect ratio of the rendering resolution.
Choosing a wrong FOV for your video game could even make your eyes hurt or feel tired, as well as lead to dizziness or nausea. This mainly refers to various PC games released after the year 2000 that are directly ported from consoles, without adjusting the FOV to new platforms.
As a general rule, the FOV of console games played on large screens that are located at a larger distance from the player’s vision should be of around 60 degrees. On the contrary, games specifically developed for laptops or smartphones should include a larger FOV of 90-100 degrees.
Depending on the game, temporary changes to the FOV can be experienced as special effects, emphasizing a certain element of the game. A reduced FOV is usually associated with a method of conveying focus, while a wide FOV may point toward a lack of control.
FOV in Virtual Reality
Determining the right FOV in VR is even more difficult, as it also depends on the size of the screen through which the virtual reality images are projected.
The angular field of view used in virtual reality represents a complex formula that takes into account the distance between the largest object and the lens, the deformation or the magnification of the lens, and the distance between the eyes and the lenses.