The basic function of an industrial lenses is to transform the light beam. In machine vision systems, the primary role of an industrial lenses is to position the imaging target on the photosensitive surface of the image sensor. The quality of an industrial lens directly impacts the overall performance of the machine vision system. Proper lens selection and installation are crucial aspects of machine vision system design. Lenses brightness is related to changes in aperture and focal length. Lens brightness is generally expressed in terms of F-number. Lenses also have an aperture component for adjusting brightness, which can adjust light transmission based on application conditions.

1.Calculating Depth of Field for Industrial Lenses
Even if the distance (W.D.) between the object and the lens changes, the image remains sharp within a certain range. This distance range is called depth of field. Conversely, for a given object plane, even if the distance between the imaging plane and the lens varies, the image remains sharp within a certain range. This is called depth of focus.

Calculation Method:
Depth of Field = F*ε*(1/β)
ε: allowable circle of focus parameters 2/3 = 0.02, 1/2 = 0.015, 1/3 = 0.01, β: magnification.

2. Industrial Lens Technology Analysis
2-1. Automatic Aperture
Adjusting the lens aperture essentially changes the size of the aperture diaphragm, thereby varying the amount of light entering and adjusting the brightness of the image surface.
This process can be performed manually or via a motorized mechanism. The latter is known as automatic aperture adjustment.

2-2. Zoom Technology
Zoom refers to the ability of a lens to adjust its focal length over a wide range of angles (usually measured by the factor of focal length change; for example, a 4x zoom means the maximum focal length is 4 times the minimum focal length). This type of lens can be used to change the image magnification (easily switching between a "large scene" and a "partial close-up"), making it highly adaptable and widely applicable.
How zoom is achieved: During the zoom process, two (or more) lens groups in an optical system move relative to each other, changing the combined focal length of the entire system (lens) while maintaining a fixed image plane position. This allows for a change in image magnification while maintaining a clear image.
This differs from single-group shift focusing, which aims to change the position of the image plane (although this also causes slight changes in the lens' focal length). Zoom, on the other hand, aims to change the lens' focal length (usually by several times), requiring a stable, fixed image plane.

2-3. Focusing Technology
For a lens, the image distances of objects at different object distances vary. The image plane of the object being observed may not necessarily coincide with the camera's photosensitive surface. To obtain a clear image, the position of the image plane must be adjusted to align with the photosensitive surface. This process is called focusing.

(1) Whole-group movement: This focusing method moves the entire lens back and forth during the adjustment process, and the image plane moves accordingly. The image is clearest when the image plane coincides with the camera's photosensitive surface. This whole-group focusing method does not change the optical structure of the lens, and the focal length of the lens does not change.

(2) Single-group movement There is another focusing method, which is to adjust a certain group of lenses in the lens so that it moves forward and backward like the other lenses, and also causes the image plane to move horizontally, eventually making the image plane coincide with the photosensitive surface, achieving a clear image. This focusing method changes the optical structure of the lens, and the focal length of the lens changes slightly (usually not much).

For example, the front lens group forms an image of an object at infinity on the Image plane (also located at the CCD photosensitive surface), with a rear working distance of L'. Now, to image a nearby object, the image plane is located at Image'. To achieve a clear image, focusing is required.
One approach is to move the entire lens group forward relative to the CCD, increasing the rear working distance to L", aligning the CCD photosensitive surface with the image plane, resulting in a clear image. This method is called whole-group moving focusing.
Another focusing method is to move only one (or several) of the individual lenses in the lens group, which can also achieve the desired focus, as shown in the figure below. By moving the fourth lens forward from position A to A', the image plane for a nearby object returns to a position where it overlaps with the CCD, resulting in a clear image. This focusing method is called single-group moving focusing.