A company needs to implement a CCTV system that will monitor a large area outside the facility. Which of the following is the correct lens combination for this?

A.
A wide-angle lens and a small lens opening

B.
A wide-angle lens and a large lens opening

C.
A wide-angle lens and a large lens opening with a small focal length

D.
A wide-angle lens and a large lens opening with a large focal length

Explanation:
A: The depth of field refers to the portion of the environment that is in focus when shown on the monitor. The depth of field varies depending upon the size of the lens opening, the distance of the object being focused on, and the focal length of the lens. The depth of field increases as the size of the lens opening decreases, the subject distance increases, or the focal length of the lens decreases. So if you want to cover a large area and not focus on specific items, it is best to use a wide-angle lens and a small lens opening.