Explanation of parameters of industrial lens

Depth of field:

When the focus of a certain object is clear, all the scenery from a certain distance in front of the object to a certain distance in the back of the object is also clear. The distance from front to back which the focus is quite clear is called the depth of field. The depth of field is divided into front depth of field and back depth of field. The back depth of field is deeper than the front depth of field. When the depth of field is deep, the scene which is far away from the focus is clear while the depth of field is shallow, the scene is blurred.

 

Focal length:

From the optical principle, the focal length is the distance from the focus to the center of the lens. For the lens, the focal length has a very important significance. The length of the focal length is proportional to the size of the image. The longer the focal length is, the bigger the size of the image while the shorter the focal length is, the smaller the size of the image.The length of the focal length is inversely proportional to the size of the visual angle. The longer the focal length is, the smaller is the size of the visual angle and vice versa.The length of the focus is inversely proportional to the depth of field. The longer the focal length is, the smaller the depth of field is and vice versa.The length of the focus is inversely proportional to the intensity of the sense of perspective. The longer the focal length is, the weaker the sense of perspective is and vice versa.The length of the focus is inversely proportional to the contrast. The longer the focal length is, the smaller the contrast is and vice versa.

Focus distance:

The further the focus distance is, the deeper the depth of field is and vice versa.Therefore, the lens of a large focus distance should be chose when shooting a long distance view and vice versa.The focus distance of lens is expressed by cm, which is clear at a glance.

Visual angle:

The angle formed by the center point of the lens to the two ends of the imaging plane diagonal is visual angle of the lens.For the same imaging area, the shorter the focal length is, the larger the visual angle is.For the lens, the visual angle mainly refers to the range of visual angle that it can realize. When the focal length becomes shorter, the angle becomes larger. It can shoot a wider range, but it will affect the clarity of the object.When the focal length becomes longer, the angle becomes smaller. The objects that are further away will become clear, but the width of the shot is narrowed.

Magnification:

Magnification refers to the size of the original image of the object which changed through the adjustment of the lens.Although it is called magnification, some of the lens is likely to play a role in narrowing.If the product is identified as 1:4, it means that it can be up to four times through the lens.

Aperture blade number:

The size of the lens aperture is adjusted by the change of the blade inside the lens.The aperture blade number is the number of blades used to adjust the aperture of the lens.In general, the more the number is, the higher accuracy it will be able to achieve when adjusting the aperture.

Aperture:

Aperture is a light device used to control the light into the light body through the lens. It’s usually in the lens. We are using F value to express the aperture size. focal length/ diameter of the lens. From the above formula, to achieve the same F value, the diameter of a telephoto lens is longer than that of short focus lens.The complete aperture value series are as follows: F1， F1.4， F2， F2.8， F4， F5.6， F8， F11， F16， F22， F32， F44， F64.Here it’s worth mentioning that the smaller the F value is, the more light will get into lens in the same unit of time. And the light of upper level is two times than that of next level.For example, when the aperture adjusted from F8 to F5.6, the light is two time than before. We also said that the aperture is one magnitude large than before.