Night vision is yet another chapter within the video camera category.
Stefan Pryor, sales manager for L-3 Electro-Optical Systems offers a few key performance metrics to define the performance of a night vision device: Center resolution, the device's imaging tube and signal-to-noise ratio (SNR).
He says one may want a strong gain on the night vision product and with the camera. "This allows you to adapt the amount of light coming through the night vision tube."
In addition to gain, the environment affects night vision devices by range and resolution, Pryor says. He suggests the area of surveillance, whether rural or other, be considered. "You need to pay attention to the gain and type of tube: Thin filmed, unfilmed and what kind of tube is inside the device," he advises.
Two problems arise with the concept of lighting. (1) The recording needs to be adequately lit, yet (2) in tactical and surveillance, a bright light will advertise the camera's presence — or worse, a SWAT member's location.
"Lighting is paramount, extremely important and highly overlooked in terms of what a setup really is like," says Sperry West's Barry Levine. In a surveillance situation, if the camera is pointed at a door, any light coming in when that door is opened may overwhelm the camera's balance. He explains that if the camera "sees" all that light, its circuitry may automatically darken the recording, thus leaving only a silhouetted subject.
Many times tactical missions require officers to remain covert; a camera's emitted light should not turn the officer into a target.
Infrared technology may be a possible solution; however, while the beam may be invisible, it is possible to see the source — a red-like glow, explains Barry Levine.
"It depends on the nanometers," he continues, "you've usually got to be around the 950 nanometer range to have nothing visible with no glow." The drawback of long-range "totally invisible" technology is that it comes with an expensive price tag — beyond the budgets of many smaller local police departments.
One alternative solution could be an image intensifier. In her experience, Kari Yeh, research marketing manager for L-3 Infrared Products, points out that often law enforcement chooses image intensifiers for low-light work due to their lower price point. "However, it can't work in complete darkness; usually you need a little bit of light," she adds.
Ultimately, Barry Levine suggests buyers focus on whether the camera is going to be handheld or wearable, or whether it can be set up inside a vehicle or room. "Buyers need to know what they are going to use it for," he adds. The agency then may want to investigate whether the camera is meant for inside or outside surveillance, if and how the scene is being transmitted, stored or viewed.
"It's not a hard sell in convincing police agencies that they need cameras," says Garrett. "I think they realize they need them, yet the little nuances between the systems are important."
There is no one solution for everything; while nothing truly works 100 percent for every investigation, it is the same for equipment, reminds Barry Levine. "You can't buy something and hope it's going to be a cure-all."