What is a characteristic of a varifocal lens?

A varifocal lens is designed with the capability to change its focal length, allowing the user to zoom in or out as needed. This characteristic enables the lens to be adjusted for different perspectives and object distances, which can be done either manually or through motorized controls. This flexibility is fundamental to varifocal lenses, differentiating them from fixed lenses that only provide a single set focal length.

The ability to adjust the focus enhances versatility in various applications, whether in surveillance, photography, or any scenario where adapting to changing conditions is necessary. This feature elevates the lens's usability, making it suitable for environments where the subject matter may be at varying distances.

In this context, the other options do not accurately describe the core functions of a varifocal lens, as they either pertain to fixed-length specifications, automatic focusing mechanisms not guaranteed in all varifocal lenses, or field of view characteristics that are not exclusive to varifocal designs.