A Milesight Technology Moment Auto Back Focus.pdf


Auto back focus has become a more and more common feature in box cameras. And this trend will continue or strengthen with ABF becoming less of a nice feature to have, and more of a standard feature expected of all new box cameras.

What is Auto Back Focus?

The Auto Back Focus functionality in security cameras is accomplished by adjusting the image sensor's distance with the lens, which enables differing back focal lengths for the lens. ABF technology allows Milesight box cameras to adjust the position of the image sensor to achieve optimal focus. This feature can also be accessed via the Web client. When the focus of the lens does not reach the requirements, ABF can help to complete the last step of focusing.

Inner structure of ABF Camera
Figure 1

Why need Auto Back Focus?

Different from motorized lens cameras, the box camera offers various zoom fixed lens. The fixed lens need to focus manually and may need a difficult slight adjustment which can normally be done by just slightly turning the lens one way or the other. While with auto back focus, you just need to click one button to finished the focusing, which greatly save the installation time and get better image focus.

ABF camera's back
Figure 2

How to use Auto Back Focus?

Step1: Focus manually. After the box camera being installed, it firstly needs to adjust a varifocal lens manually to get a relatively clear image. In the image below (Figure 3) it is a fairly typical varifocal lens in the box camera. The top will adjust the focus. It is designated by the letter N (for near) and the infinity symbol (for far). You will need to loosen the set screw in order to adjust it. The focal length is designated by W and T. (Wide angle and telephoto) which will be adjusted by firstly loosen the screw. Once you have adjusted the field of view you want, you can then make the adjustment for the focus to bring everything into a sharp clear image. Lastly, you need to tighten down the set screws so that your settings remain.

structure of lens
Figure 3

Step2: Push the ABF button. As you set a relatively clear image, it is easy to get the most clear image by just pushing the ABF button (Figure 4). A electrical motor inside the box camera will slightly move the sensor to the best focus location. Also, there is “Auxiliary Focus” on the web interface (Figure 5), which will help to focus just as the ABF Button do.

ABF button's location
Figure 4

Advantage of Auto Back Focus

Labor and time saving.

Focusing more accurate and faster.


Keeping customer-oriented, Milesight never stop to bring our customer the more functional and powerful products. By adding the useful functionality, Auto Back Focus, to Milesight Pro Box Network Camera, it can focus automatically by clicking one button to save time and labor.

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