Basic parameters of industrial lenses

        Field of view: also known as field of view scale, refers to the visible size of objects that can be observed.

       Working Distance： The distance from the front of the lens to the surface of the object being inspected, at which the lens is able to produce a clear image.

       Resolution： The ability of a lens to clearly distinguish the details of the object being photographed, with the ability to distinguish the number of black and white lines within 1mm of the image plane. The resolution unit is "line pair/millimeter" (lp/mm). Generally speaking, a million pixel lens has a resolution of 100 pairs/mm.

       Depth of View： In the scene space, the depth interval within a certain distance before and after the focusing plane that can still achieve clear imaging is the simplified depth scale of the scene that achieves a relatively clear impression on the practical image plane.

       Focal Length： Focal length is the distance between the clear impression formed from the center point of the lens to the focal plane. When the focal length value is small, the viewing angle is large, and the observed scale is also large. However, the imaging of objects far apart is not very clear. When the focal length value is large, the viewing angle is small, and the observation scale is small, but objects far apart can still be clearly imaged. There are two types of lenses: fixed focus and zoom. Common industrial lens focal lengths include 5mm, 8mm, 12mm, 25mm, 35mm, 50mm, 75mm, etc. Generally speaking, the smaller the focal length, the more expensive the price.

       Aperture: Iris， It is a device used to control the amount of light entering the sensitive surface of the camera through the lens. When shooting high-speed moving objects, a large aperture is required due to the short exposure time. The aperture size is generally represented by F, which is measured by the ratio of the lens focal length f to the aperture diameter D. When the physical aperture of the aperture remains constant, the farther the distance between the lens center and the photosensitive device, the larger the F value and the smaller the aperture; On the contrary, the smaller the F value, the larger the aperture. Generally, the aperture is adjusted by adjusting the aperture size. The complete aperture value series is as follows: F1，F1.4，F2，F2.8，F4，F5.6，F8，F11，F16，F22，F32，F44，F64。