Aperture F Definition:

The lens aperture f-value is the ratio of the focal length of the lens to the diameter of the lens aperture, i.e. f = focal length / lens aperture diameter. The smaller the ratio, the more light the lens allows to pass, the larger the aperture; conversely, the larger the ratio, the smaller the aperture. Aperture f-value is used to characterize the size of the aperture, common aperture f-value F2.8, F4, F5.6, F8, F11, F16 and so on.

Effect of aperture F on machine vision:

1、Affect the brightness of the image: The F value of the aperture is used to control the amount of light passing through the lens. A smaller F-value (i.e., larger aperture) allows more light to pass through the lens, thereby increasing the brightness of the image. Conversely, a larger F-value (i.e., a small aperture) reduces the amount of light passing through the lens, resulting in a darker image. In machine vision systems, the brightness of the image is critical for subsequent image processing and recognition.

2、Affect the depth of field: the F value of the aperture is also closely related to the depth of field (DOF). Depth of field is the distance between the uppermost surface and the lowermost surface of the object being clearly imaged. A small F value (large aperture) will reduce the depth of field, so that only objects near the plane of focus can be clearly imaged, while objects away from the plane of focus will appear blurred. Conversely, a larger F-number (smaller aperture) will increase the depth of field so that a wider range of objects can be clearly imaged. In machine vision, according to the needs of the application to select the appropriate depth of field is essential to ensure the quality of imaging.

3、Affect the image quality: the F value of the aperture will also affect the quality of the image. Too large an aperture may lead to purple edges, glare and other problems in the image, while too small an aperture may result in the loss of image details due to diffraction effects. Therefore, when selecting the F value of the aperture, you need to weigh the relationship between image brightness, depth of field and image quality.

The industrial lens aperture f-value has an important impact on the machine vision system, which controls the amount of light entering the camera and the depth of field of the image, thus affecting the brightness, clarity and quality of the image. Therefore, when selecting and using industrial lenses, you need to reasonably set the aperture f-value according to specific application scenarios and needs to get the best machine vision results.