Which of the following is not required for photo surveillance equipment?

The correct answer highlights that a smartphone for communications is not specifically required for photo surveillance equipment. While smartphones can be helpful for communication and immediate access to information or locations, they are not essential components of the actual surveillance setup. Photo surveillance primarily relies on the camera and its associated hardware, such as lenses and printers, to capture and produce high-quality images.

The other components mentioned serve specific functions critical to effective photo surveillance. A digital camera with a 50mm lens is a typical choice for capturing clear images at a distance, providing the versatility needed to document subjects without being obtrusive. A high-resolution printer is necessary for producing physical copies of the images, which can be used for reports or evidence in investigations. An electronic flash built into the camera enhances the quality of images taken in low-light conditions, thus broadening the usability of the surveillance equipment. Each of these elements contributes directly to the equipment's functionality in gathering reliable visual evidence.