The lens hood is designed to reduce flare and protect the lens, among other things. WHAT IS THE PURPOSE OF A LENS HOOD? The lens hood is a piece of plastic that clips/screw onto the front of a camera lens and extends beyond it. Lens hoods serve two primary purposes: (1) reducing lens flare, and (2) protecting the lens from damage. The intended purpose of the lens hood is simply to reduce lens flare, but the protection it provides to the glass elements of the lens is a beneficial side-effect.