Night Vision and forward-looking infrared (FLIR) imaging each pierce the darkness in different ways. Both offer pros and cons, and so we found a dark stretch of the St. Johns River near Sanford, Florida, to test these scopes. We dropped anglers’ marker buoys every 15 seconds while traveling 3.5 mph (approximately 25 yards per target) and then anchored 30 seconds from the last of eight markers. First we sighted down the string to see how many we could spot. Then we weighed anchor and went hunting for the buoys in a search-and-rescue maneuver.
Bat Vision 101
Night vision and forward-looking-infrared vision are very different solutions to the same problem: how to see in the dark.
Night vision amplifies ambient light that strikes its sensor and generates visual data that is amplified and transmitted to a viewing screen. It can sometimes offer more detail because it responds to light more like the eye does.
Infrared illuminators, invisible to the eye, can be detected by night-vision scopes and enhance the image much like a flashlight does. They can also be detected by other night-vision scopes — not good for snipers.
Forward-looking infrared detects invisible heat radiation when that strikes its sensor. The signal is interpreted by a microprocessor and then transmitted to a viewing screen. Infrared viewers generate greater contrast at distant targets but are unable to detect details like buoy numbers not visible to thermal imaging.
Resolution of both the sensors and the view screens has a great deal of influence on the image you see. A larger sensor gives better information to the system, and more pixels in the viewing screen per square inch give more detail to the eyeball.
Contrast of image is everything. The fur of a raccoon blended with the brush in both night-vision technologies and diffused its heat signature with FLIR. But we “made” the masked critter when its eyeballs reflected the IR illuminator of the iGen.
Image modes allow users to change screen color to enhance viewing. Red has the least impact on night vision. The eye can detect many shades of green, so a green display can give more detail to the viewer. FLIR let us toggle between white-hot, meaning the warmest targets were whitest, to black-hot, meaning the warmest targets were darkest — helpful choices you can make when searching in different backgrounds.
Waterproof construction is very important for a marine device, and only FLIR is rated fully waterproof.