What does a Video-Iris Lens do in response to light levels?

The function of a Video-Iris Lens is primarily related to how it manages light entering the camera system. In this context, the correct answer involves the automatic adjustment of the iris size in response to varying light levels. This feature is essential for maintaining optimal exposure in changing lighting conditions, which is critical for video surveillance and photography applications.

A Video-Iris Lens is designed to automatically adjust the aperture or iris opening, allowing more or less light to reach the camera sensor based on the surrounding brightness. This automatic adjustment helps ensure that images remain clear and properly exposed, eliminating the need for manual intervention as lighting conditions change.

The other options focus on functionalities that do not pertain to the primary role of a Video-Iris Lens. While memorizing focus positions and converting signals can be functions of other types of lenses or camera components, they are not the defining feature of the Video-Iris Lens's response to light levels. Furthermore, operating only in manual mode would contradict the purpose of a Video-Iris Lens, which is designed for automatic adjustments to enhance usability and effectiveness in various environments.