We know that in the actual shooting and focusing process of industrial lenses, when the plane of the subject to be photographed is focused with manual focus, and then gently turn the focus circle left and right, sometimes it is found that the image is still clear within a certain range, and when more than After a certain range, the sharpness of the image will decrease. This involves two nouns, depth of field and depth of focus.

Depth of focus refers to the distance at which the point of an object is measured behind the lens along the axis of the imager to obtain a clearer image. Practical value of depth of focus: Before shooting, you should use a large aperture to focus, which can not only increase the brightness of the image, but also reduce the depth of focus, which is helpful for accurate focusing. After the focusing is accurate, adjust the aperture to the required gear for shooting. superior.

So what is the depth of field of an industrial lens? The depth of field of a lens refers to the ability of the lens to maintain the desired image quality without the need to refocus when objects are positioned near and far from the best focus.

The following mainly share with you the difference between depth of field and depth of focus:

1. Different meanings: the depth of field is the vertical distance that can produce a clearer image in the scene; the depth of focus is the distance that the focal plane of the image can be moved.

2. When the shooting distance decreases, the depth of field decreases and the depth of focus increases; when the shooting distance increases, the depth of field increases and the depth of focus decreases.

3. When the imaging ratio of the scene increases, the depth of field decreases and the depth of focus increases; when the imaging ratio of the scene decreases, the depth of field increases and the depth of focus decreases.

4. When the aperture is reduced, both the depth of field and the depth of focus increase; when the aperture is increased, both the depth of field and the depth of focus decrease.

5. When the sharpness requirement of the image is lowered, both the depth of field and the depth of focus increase; when the sharpness requirement of the image is increased, the depth of field and the depth of focus both decrease. 

6. The depth of focus is largely related to the manufacture of the camera; the depth of field is largely related to the reproduction of the subject.