Industrial automation systems for functions like quality inspection rely on cameras with accurate FOV settings to scrutinize products on assembly lines. They capture imaging data required for thorough product inspection by detecting defects instantly. Moreover, manufacturers can optimize their inspection processes, reduce errors, and maintain consistent product standards.

Also, let us consider a popular embedded vision application like autonomous mobile robots (AMR). These autonomous systems perform obstacle detection and obstacle avoidance (ODOA) to seamlessly navigate their environment. And many of these robots require FOVs in excess of 180 degrees. This ultra-wide FOV is achieved by using multi-camera systems.

Similarly, for the calculation of VFOV and DFOV, instead of width (or horizontal F0V), corresponding height and diagonal dimensions of the object are substituted in the above formula respectively.

FOV to focal length

The second standard size is the larger 2" diameter. Many telescopes will accept these eyepieces, though some telescopes will require an optional adapter. Not all telescopes work with 2" eyepieces. 2" eyepieces are wide-field, low-power eyepieces. Above a certain magnification (which depends on the design), 2" diameter barrels are not required, so not all wide-field eyepieces are 2"--some will still be 1.25" and this is not a disadvantage, just a function of the design. This is a common misconception. Accessories such as filters and Barlow lenses are designed for 2" eyepieces as well. 2" eyepieces typically cost $200-400, with some of the largest and highest quality eyepieces costing around $600. Some inexpensive models are also available for around $100, though these will obviously not have the features or quality of the more expensive eyepieces.

However, it is extremely important to understand that many factors determine this. There is no ‘one-size fits all’ approach to this. It is recommended that you seek help from an imaging expert like e-con Systems as you pick the right field of view and lens for your application.

FOV also depends on the distance between the camera and the object. As discussed earlier, if the objects are closer to the camera, the FOV becomes wider. This is because shorter focal lengths require shorter working distances for proper focusing. Thus, the lens to sensor distance has to be designed based on the working distance.

Conversely, if you know the FOV and the working distance, then you can calculate the dimension of the object using the below formula.

Above: Two short focal length eyepieces, one with normal eye relief and one specially designed with long eye relief. Note the difference in the size of the eye lens.

Remote patient monitoring systems rely on cameras with an optimal FOV to provide accurate and complete observations of patients. These cameras ensure that all relevant movements and conditions are captured so that healthcare providers can monitor the health of patients. It leads to timely medical interventions and improved remote patient safety.

Meanwhile, you could check out the article What are the crucial factors to consider while integrating multi-camera solutions? if you are interested in learning more about multi-camera integration.

Automated sports broadcasting systems use cameras with a wide FOV to cover entire fields or courts. Hence, all the movements within the sporting area are captured, which means viewers can experience the game in an immersive way. A wide FOV is also important for capturing aspects such as player movements and strategic plays, which enhances the overall broadcasting quality. Furthermore, wider FOV cameras streamline production by potentially replacing multiple conventional cameras, reducing setup complexity and personnel needs.

In this article, let’s explore the importance of FOV in embedded vision, the factors that determine FOV, as well as which applications rely on this the most.

FOV is one of the most critical parameters considered while integrating a camera into an embedded vision system. Whether it’s an intelligent transportation system, autonomous mobile robot, remote patient monitoring system, or automated sports broadcasting device, FOV plays a major role in ensuring the necessary details of the scene are captured. The FOV of the lens can be set as wide or narrow based on the end application requirements.

Let’s look at Autonomous Mobile Robots (AMR) as a reference. These autonomous systems perform obstacle detection and obstacle avoidance (ODOA) to seamlessly navigate their environment. Many of them require FOVs in excess of 180 degrees. This ultra-wide FOV is achieved by using multi-camera systems.

The most important eyepiece characteristic is focal length. This is the number, in millimeters, written on the side of every eyepiece. It allows you to determine the magnification an eyepiece gives in combination with a given telescope. Magnification is determined simply by dividing the focal length of the telescope by the focal length of the eyepiece.

What helps e-con stand out when it comes to this solution is our proprietary 180-degree stitching algorithm that can process images from multiple cameras to create a 180 degree image. To learn more about this solution, please visit the product page.

However, selecting and evaluating sensors and lenses can be challenging. The right combination can help build a highly optimized embedded vision system that meets all your standards. Of course, when selecting a lens for an embedded camera, numerous factors, such as Field Of View (FOV), must be considered.

FOV to focal length calculator

Each embedded vision application has different sensor size requirements to get the best output. A small sensor will have a narrow field of view while a large sensor can provide a wide field of view.

Eyepieces determine the magnification and field of view of a telescope. Different eyepieces are used to view different objects. Some objects, such as nebulae and star clusters, appear quite large and are best viewed at low magnifications (which give a wider field of view), whereas planets appear very small and are normally viewed with high-magnification eyepieces. One of the most common misconceptions in amateur astronomy is that magnification is the most important aspect of a telescope. In reality, the diameter (aperture) of a telescope determines its power and different eyepieces are used to get the best view of a given object. Often the best view is at a low magnification. Be sure to read the section on Understanding Magnification for more details.

You also have an option to capture the same field of view with sensors of different size. This can be done using a lens with the appropriate focal length. As a result, the same FOV can be achieved using a small sensor with a short focal length lens and a large sensor with a long focal length lens.

Having 2 or more cameras enables a higher resolution, prevents lens distortion, and offers a wider FOV. To achieve high imaging quality in multi-camera systems, a lens having an FOV of around 60-70 degrees is usually chosen. But it is important to note that this is determined by a multitude of factors. There is no ‘one-size fits all’ approach to this. It is recommended to take the help from an imaging expert like e-con Systems as you go about picking the right field of view and lens for your application. Please feel free to write to us at camerasolutions@e-consystems.com if you need a helping hand.

Focal length is the defining property of a lens. Simply put, it is the distance between the lens and the plane of the sensor, and is determined when the lens focuses the object at infinity. It is represented in mm. Focal length depends on the curvature of the lens and its material. The shorter the focal length, the wider the AFOV and vice versa. Please have a look at the below image to understand this better:

fov是什么

Please write to us at camerasolutions@e-consystems.com if you need expert help integrating cameras with different FOVs into your applications.

Generally for a sensor, FOV refers to the diagonal measurement – which is called DFOV or Diagonal FOV. Horizontal FOV (HFOV) and Vertical FOV (VFOV) will vary based on the aspect ratio of the image sensor used.

Almost all telescopes are designed to be used with 1.25" diameter eyepieces. Most telescopes will include at least one 1.25" eyepiece. Accessories such as Barlow lenses and filters are designed to thread into the barrel of these eyepieces, so such accessories are also distinguished by size. Good 1.25" eyepieces typically cost $40-200, although there are more and less expensive models.

Above: Increasing the magnification makes the image larger, but the image gets dimmer and the field of view gets smaller

field ofview中文

Having two or more cameras enables a higher resolution, prevents lens distortion, and offers a wider FOV. To achieve high imaging quality in multi-camera systems, a lens having an FOV of around 60-70 degrees is usually chosen.

This means that a smaller number on an eyepiece gives a higher magnification. A 10mm eyepiece would provide twice as much magnification as a 20mm eyepiece. It also means that the same eyepiece gives different magnifications on different scopes. A 10mm eyepiece would be low power on a short-focal-length scope but high power on a long-focal-length scope. For example, on an 80mm short-focal-length refractor, a 10mm might only provide 40x magnification, but the same eyepiece on a 10" Schmidt-Cassegrain telescope would give 300x.

Field of view

For example, imagine that the camera and the object are fixed at a working distance of 30cm. In this case, the HFOV and VFOV are measured manually using a scale (in mm) as shown below:

The amount of sky seen through an eyepiece (called the true field of view) is determined by both the magnification and the eyepiece's apparent field of view. Apparent field of view is a design characteristic of an eyepiece design. Some eyepieces have narrow apparent fields and some have wide apparent fields. If the magnification is kept the same (i.e., the eyepieces have the same focal length), an eyepiece with a wider apparent field will have a wider true field.

There are two standard sizes of telescope eyepieces. The sizes are determined by the diameter of the eyepiece barrel that fits into the telescope. The two standard sizes are 1.25" and 2". A third size, 0.965", is a smaller standard that is usually best to avoid (see below).

Prabu is the Chief Technology Officer and Head of Camera Products at e-con Systems, and comes with a rich experience of more than 15 years in the embedded vision space. He brings to the table a deep knowledge in USB cameras, embedded vision cameras, vision algorithms and FPGAs. He has built 50+ camera solutions spanning various domains such as medical, industrial, agriculture, retail, biometrics, and more. He also comes with expertise in device driver development and BSP development. Currently, Prabu’s focus is to build smart camera solutions that power new age AI based applications.

From the previous section, we understood the definition of FOV and its relation with several other lens parameters. Let us now discuss how to choose the right FOV for an embedded vision application.

fov参数

e-con Systems has led from the front when it comes to innovation in embedded vision. And one of our key strengths is the platform side expertise especially on the NVIDIA Jetson series. Leveraging this, e-con has designed many multi-camera solutions that offer an FOV of up to 360 degrees.

Above: Increasing the magnification may not always result in a better view, especially if the object being viewed is very large

Smart traffic systems utilize cameras with a wide FOV to seamlessly monitor and manage road traffic. Such cameras capture comprehensive views of large areas for performing real-time traffic flow analysis and incident detection. Covering wide road sections also means they can promptly identify traffic violations, accidents, and congestion. Additionally, the broader view empowers advanced features like vehicle counting, object classification and lane discipline monitoring. This provides crucial real-time data that helps optimize traffic flow and improve overall safety.

You can also change field of view by simply changing magnification. If the apparent field is kept the same, a lower power eyepiece will give a wider field of view. To view very large objects such as the Andromeda Galaxy or Pleiades star cluster, you need a very large field of view and hence a very low magnification. Field of view is very important for getting the best view.

fov和焦距的关系

Most embedded camera applications require the FOV to be wider enough to cover a large viewing area. For instance, a fish-eye lens is characterized by a wider FOV and larger depth of field (DOF) and is hence suitable for surveillance applications. On the other hand, for a zoom/telescopic application, you might require a normal/narrow FOV.

Take a look at the diagram below. It shows that both a telescope and your eye focus light to a point. Placing an eyepiece at the focal point of a telescope then creates a light beam which is neither converging nor diverging. Your eye can then focus the light beam exiting the eyepiece.

Viewangle

Now let us discuss FOV calculation. In many applications, the required distance from an object and the desired field of view (which determine the size of the object seen in the frame) are known quantities. This information can be used to directly determine the required angular field of view (AFOV) as shown below.

A typical eyepiece collection would include 3 eyepieces: one low power, one medium power, and one high power. The usual magnification range depends on the telescope, but for most scopes the normal range might be from 50x to 250x.

The final eyepiece size is the one to avoid. 0.965" eyepieces are the standard size for "department store" telescopes. These inexpensive telescopes often frustrate new stargazers, and one of the primary reasons is that viewing through 0.965" eyepieces is all but impossible. Also, standard accessories such as Barlow lenses and filters are not normally available for these eyepieces. And you are usually stuck with the eyepieces that come with the scope since 0.965" eyepieces are rarely sold separately. The difference between a scope with 1.25" eyepieces and one with 0.965" eyepieces is usually the difference between a scope that ends up in the yard showing you the wonders of the universe and one that ends up in the closet collecting dust.

Many modern-day embedded vision systems utilize multiple types of lenses and sensors with different feature sets and varying costs. The design of the camera systems integrated with these components plays a huge role in achieving the required image quality.

Broad perspectives generally equip Autonomous Mobile Robots to navigate complex environments and avoid obstacles. A wide FOV also ensures that robots can detect and analyze their surroundings in real time, boosting their ability to move safely and operate in dynamic environments, such as warehouses, manufacturing floors, and public spaces. A large vertical FOV ensures that obstacles at any height are detected, allowing robots to navigate under hanging obstacles such as shelves or overhead conveyor. For warehouse AMRs, two cameras placed on opposing corners, each providing a 270° FOV, can offer complete situational awareness. This setup enables the AMR to navigate freely in all directions—left, right, forward, and backward—while also turning efficiently without worrying about blind spots or objects coming from behind.

Field of view (FOV) is the maximum area of a scene that a camera can focus on/capture. It is represented in degrees. There are three ways to measure the field of view of a camera – horizontally, vertically, or diagonally as shown below.

e-con Systems has 20+ years of experience designing, developing, and manufacturing OEM cameras. That’s why we understand the nuances involved in selecting lenses with the right FOV for your application. We can expertly guide you through the entire process of selecting the lens rather than merely acting as a camera supplier.

Why are eyepieces even necessary? A telescope is an optical system that creates an image, just like a camera lens creates an image on film. In fact, placing a camera at the focus of a telescope will also capture an image, since the telescope becomes the camera lens. But, placing your eye at the focus point of a telescope does not produce an image. Why not? Because your eye is also an optical system. Your eye focuses light just like a telescope does, and it cannot focus on a real image such as that created by a telescope. It requires a virtual image, which is what an eyepiece creates.

This is an important aspect of many eyepieces. Eye relief is the distance from the eyepiece to the observer's eye. The shorter this distance, the more difficult it can be to observe. Also, if the observer must wear eyeglasses, short-eye-relief eyepieces can be very difficult or impossible to use. Long-focal-length eyepieces (usually low power) inherently have long eye relief, so they do not need to be specially designed to increase eye relief. Short-focal-length eyepieces (usually high power), on the other hand, do not inherently have long eye relief and must be specially designed to make them easier to use.

Most of the embedded camera applications require the FOV to be wider enough to cover a large viewing area. For instance, a fish-eye lens is characterized by wider FOV and larger depth of field (DOF) and hence is suitable for surveillance applications. On the other hand, for a zoom/telescopic application, you might require a normal/narrow FOV.

And one of the most popular among those solutions is e-CAM130A_CUXVR_3H02R1 180° FOV camera – a synchronized multi-camera solution that can be directly interfaced with the NVIDIA® Jetson AGX Xavier™ development kit. This camera solution comprises of three 13 MP camera modules that are based on the 1/3.2″ AR1335 CMOS image sensor from onsemi®. These 4K camera modules are positioned inwards to create a 180° FOV as shown in the image below: