FIXME **This page is not fully translated, yet. Please help completing the translation.**\\ // (remove this paragraph once the translation is finished) // ====Field of View==== **I. Concept of Field of View**\\ In the field of photography, **Angle of View (AOV)** and **field of view (FOV)** are often used interchangeably, both referring to the maximum angular extent of the scene that a camera can "see". Specifically, **AOV** refers to the angular measurement of this extent, while the concept of **FOV** is broader and can express the extent in terms of angles, dimensions, etc., but in photography, it specifically refers to the angular range.\\ {{ yanding:成像基础知识:成像系统:成像质量问题:入瞳.png?600 |}} From an optical perspective, the __Angle of View is the angle subtended by the entrance window at the center of the entrance pupil__, as shown in the figure above. Here, the field stop is the aperture that limits the field of view (i.e., the frame of the image sensor in the figure), and the entrance window is the image of the field stop formed by the optical system between it and the object. **II. Classification of Field of View**\\ Based on the measurement direction, the field of view can be classified into **horizontal field of view (HFOV), vertical field of view (VFOV), and diagonal field of view (DFOV)**.\\ **Horizontal field of view (HFOV)** refers to the angle of view in the horizontal direction.\\ **Vertical field of view (VFOV)** refers to the angle of view in the vertical direction.\\ **Diagonal field of view (DFOV)** refers to the angle of view along the two diagonals. The specific measurement range is shown in the figure below.\\ {{ yanding:成像基础知识:成像系统:成像质量问题:企业微信截图_17604081943519_1_.png?600 |}} (Image source: https://commons.wikimedia.org/w/index.php?curid=5294848) **III. Factors Affecting Field of View**\\ The size of the field of view depends on the **focal length of the lens** and the **size of the image sensor**.\\ **1. Focal Length**\\ Focal length refers to the distance from the optical center of the lens to the focal plane of the sensor (the plane where the image is sharply focused). For a given image sensor size, the longer the focal length of the lens, the smaller the field of view. Conversely, the shorter the focal length, the larger the field of view.\\ | {{ yanding:成像基础知识:成像系统:成像质量问题:24-72mm_zoom_demo.jpg? |}} | | Five images captured with cameras using different focal lengths of 24, 28, 35, 50, and 72 mm, but with the same image sensor | (Image source: https://commons.wikimedia.org/wiki/File:24-72mm_zoom_demo.jpg) **2. Image Sensor Size**\\ The size of the image sensor affects the camera's crop factor (also known as "focal length multiplier"). For a given lens focal length, the larger the image sensor, the larger the field of view. Conversely, the smaller the image sensor, the smaller the field of view.\\ | {{ yanding:成像基础知识:成像系统:成像质量问题:lenscropfactor.png? |}} | | Field of view cropping in cameras with different sensor sizes but the same lens focal length | (Image source: https://commons.wikimedia.org/wiki/File:LensCropFactor.png) **IV. Measurement of Field of View**\\ **3.1 Test Equipment:**\\ Camera module, image acquisition card, image capture software, FTB glare test fixture, HS-FTB control software {{ yanding:屏幕截图_2025-07-23_171127.png?direct |}}\\ {{ yanding:屏幕截图_2025-07-23_172523.png?direct |}} {{ yanding:屏幕截图_2025-07-23_171251.png?direct |}} **3.2 Test Procedure:**\\ 1. Connect the camera module using the image acquisition card, open the image capture software to power it on and display the image. 2. Adjust the FTB glare test fixture so that the image is exactly centered in the visible frame. 3. Based on the HFOV, VFOV, and DFOV provided for the module, use the **HS-FTB** to perform initial rotations for the horizontal, vertical, and diagonal fields of view. If the provided data is accurate, after the movement, exactly half of the light source should be visible at the left, right, top, bottom, and diagonal edges. If the provided HFOV, VFOV, and DFOV are inaccurate, adjust manually until exactly half of the light source is visible at the left, right, top, bottom, and diagonal edges. For example: Suppose a module has an HFOV of 90°, a VFOV of 55°, and a DFOV of 110°. Then the horizontal field of view is 45° on each side. Enter 45 or -45 in the target angle position in the HS-FTB control software shown below, click "Rotate", wait for the rotation to complete, and check the visible frame in the image capture software. Half of the light source should be visible on both the left and right sides.\\ {{ yanding:屏幕截图_2025-07-23_170047.png?direct |}} The test for the vertical field of view is similar to the horizontal one, except that you need to enter 90° in the target angle position in the HS-FTB control software shown below to switch to measuring the vertical field of view. Now, the vertical field of view of the module is 55°, which means 27.5° on each of the top and bottom sides. Enter 27.5 or -27.5 in the target angle position in the figure above, and click "Rotate". Wait for the rotation to complete and check the visible frame in the image capture software. Half of the light source should also be visible on both the top and bottom sides.\\ {{ yanding:屏幕截图_2025-07-23_170027.png?direct&500 |}} The test procedure for the diagonal field of view is basically the same as for the vertical field of view, except that you need to enter the rotation angles in the two target angle positions shown below. The Roll angle for the diagonal needs to be determined by trial and error. First, enter the required rotation value in the target angle position for Roll, which is typically around 30°, 32°, or 28°. Second, enter a value in the target angle position for Yaw. This value can be any number between 10° and half of the diagonal field of view. If the light source moves along the diagonal in the image capture software, the angle entered for Roll is correct (note that if the entered angle is large, there might be a deviation of 1~2°).\\ Now, the diagonal field of view of the module is 110°, which means 55° on each side. Enter 55 or -55 in the target angle position for Yaw, and click "Rotate". Wait for the rotation to complete and check the visible frame in the image capture software. Half of the light source should be visible at the diagonal edges.\\ {{ http://ydadmin.rdbuy.com.cn/ueditor/php/upload/image/20230816/1692149951475473.png?direct }} **See Also**\\ [[:camera测试用例]]、[[:测试用例]]、[[:riqa简介]]