Thermal vs. Night Vision: Similarities and Differences in the Dark

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It was pitch dark in east Texas, but there was no doubt the hogs were coming my way. I heard the squalling of two pigs fighting in the distance, then the sound of brush rustling close by as the sounder of six feral pigs made their way to the bait. As they snuffled and rooted in the sandy earth, I raised my Pulsar thermal to my eye and the scene was illuminated. The hogs circled around the feed, and directly in the center was the largest boar whose head glowed ghostly white against the black background as he vacuumed up corn kernels.

I slowly lowered the handheld unit and lifted the Wilson Combat .300 Ham’r rifle. The boar appeared in the thermal riflescope with crosshairs positioned on the junction of his neck and shoulder. When the rifle came steady, I fired, and the white, round form of the boar dropped dead in the sand.

Pigs are a major problem in many areas of the country, and these hogs had learned that showing up to feed in daylight meant the chance of encountering armed hunters. But the use of thermal allowed me to hunt in total darkness, and that offered a major advantage to reduce hog numbers on the ranch.

Not so long ago the use of night vision and thermal optics was largely limited to military and law enforcement applications and those wealthy enough to pay the extremely high prices these optics fetched. Fortunately, even as technology improved and the market expanded, the cost of ownership for night vision and thermal optics has dropped dramatically. Today you can equip your firearm for night hunting without spending much more than you would for a high-end traditional day optic. But how do night vision and thermal optics work, and which is right for you?

Night Vision Optics

Kevin Reese is a former U.S. Marine who currently serves as the media relations manager at Sellmark, so he is well-versed in the functions and limitations of both night vision and thermal optics. According to Reese, the use of night vision began during World War II with the advent of near infrared (NIR) night vision optics. The setup was rudimentary by today’s standards; a large NIR illuminator was positioned atop the riflescope to provide a close-quarters sighting system for night operations. By the 1950s, technology had advanced and an improved NIR illuminator allowed for better range and an improved sight picture.

To be succinct, night vision optics gather photons of light which pass through a photocathode, microchannel plate and a phosphor screen. When photons of light enter the tube they are converted to electrons, and those electrons are multiplied. Afterwards, the electrons are converted back to photons which form the green image that our eyes can detect. Night Vision can be either passive or active. Passive night vision relies on traces of ambient IR light from the moon, stars, artificial sources or an illuminator, while active night vision requires infrared illumination to function.

Traditional night vision is often referred to as “generational” night vision, according to Reese, and there are currently three night-vision generations recognized by the U.S. Army Night Vision and Electronics Sensor Directorate. Gen 1 night vision utilizes the most rudimentary technology of the three, offering a clear view to about 100 yards with some “blooming” in bright light. Gen 2 night vision arrived during the Vietnam era. It was much more compact than Gen 1 NV and offered better resolution without the tendency to bloom. Gen 2 NV also offered a much greater range—up to 250 yards—which made it far more useful in combat applications. The most advanced NV optics are the current Gen 3 offerings which include auto-gating that drastically illuminates bloom.

Improved resolution in Gen 3 NV optics offers a much better range—sometimes as much as 400 yards—and advanced auto-gating. Most modern NV equipment comes with onboard IR illumination that boost range (up to 500 yards for Gen 3). That makes traditional (or generational) night vision handhelds, helmet-mounted optics, and firearm optics very useful for night hunting applications. Price varies according to generation and feature list, but Reese told me that Gen 1 NV optics can be purchased for as little as $200, making them the most affordable option of the group. Gen 3 optics start at around $3,000 and rise depending on features, but they do offer better range and a clearer sight picture. Reese warns, however, that traditional night vision is limited for daytime use. Even with auto-gating features the blooming can result in distortion. Traditional night vision optics, then, are primarily regulated for use under cover of darkness.

Digital Night Vision

Traditional or generational night vision optics are not the only option, though. According to Reese there are also digital night vision optics, which function differently than traditional night vision. Rather than converting light photons to electrons, digital night vision (or DNV) converts the incoming photons to an electrical signal that is displayed as an LCD image or an active matrix organic light emitting diode (AMOLED). AMOLED images tend to be crisper, and they are more energy efficient which means, generally speaking, AMOLED offers longer battery run time. DNV optics don’t have the green hue associated with generational night vision, and according to Reese you can expect performance and image qualities with DNV that falls between Gen 1 and Gen 2 traditional night vision. DNV is fairly affordable, too, with prices starting around $400 for quality DNV optics like Sightmark’s Wraith HD.

Today hunters have lots of options when choosing a night vision optic, and with prices starting at just a few hundred dollars basic NV equipment is very affordable. And, as my experience in some east Texas rice fields demonstrated, NV can be very effective. But it’s certainly not the only technology available to hunters.

The Thermal Revolution

The story of thermal optics began well before the advent of night vision, according to Reese. Scientists have long known that objects produce and hold heat, but it wasn’t until astronomer Samuel Langley invented the first bolometer—a device for measuring thermal radiation—in the late nineteenth century that the use of thermal heat signatures became practical.

Langley’s early experiments were the basis of today’s thermal technology. Put simply, thermal optics infrared radiation emitted by an object is focused in the optic and detectors within the thermal optic construct an image of the varying heat signatures known as a thermogram which, in turn, is converted to the image we see. Standard glass lenses will not function in thermal optics and so Germanium glass must be used, and Germanium isn’t cheap. That’s one reason why thermal optics have traditionally been so expensive.

Expensive is a relative term, and in recent years the price of thermal scopes has dropped dramatically. Twenty years ago even basic thermal units with limited capabilities cost north of $10,000, but today you can purchase a quality thermal optic starting at an average of $2,000, not much more than a precision target scope. Today’s thermals offer a wide array of additional features not traditionally found on NV optics, too, such as picture-in-picture displays, video recording, and various color palettes that allow you to adjust display settings.

Thermal optics have other advantages over NV as well. For starters, they are passive, which means there’s no need for natural or artificial illumination. Detection ranges extend past 1,000 yards, and today’s thermals can detect variations in temperature of less than one degree Fahrenheit so nothing escapes detection. Thermals offer a clearer sight picture than night vision at most ranges. It’s also possible to see heat signatures of animals that are obscured by brush.

Thermal optics are indeed more expensive than NV, but Reese told me that in most instances hunters will benefit from the advantages of thermal optics. When I asked if he knew of any circumstance where NV equipment was superior he recounted the story of a night shoot in Georgia with thermal optics where a sudden cold front actually chilled the steel targets to the same temperature as the ground, rendering them essentially invisible. In such cases NV would have worked better, but that’s an issue specific to target shooting, not hunting.

Thermals are very versatile, and owners will quickly find that they are handy for a variety of applications. They’re great for observing wildlife at night, and handheld thermals are great for home and personal defense because you can switch off the lights in your home and view your surroundings in total darkness. I doubt I’ll ever camp in bear country again without a handheld thermal. It’s much more comforting to scan the darkness for signs of large predators before hiking to the latrine, and when you’re retrieving a downed animal you can determine whether or not a grizzly has staked a claim to your trophy from a substantial distance.

Thermal or NV?

Night vision optics have more limited capabilities than thermals, but they also carry a much lower price tag. If the scope of your night vision hunting activities includes dispatching nuisance animals around your cabin then even the most basic NV equipment will suit your needs. If, however, you’re planning to hunt coyotes at night on the wide, windy plains of Wyoming you’ll be better served by a quality thermal, if only because you’ll see the animals approaching from a greater distance through sagebrush and will have more time to shoot.

There are also questions of legality. More than half of states allow night vision optics for hunting at night, but there are stipulations. For example, my home state allows the use of night vision for hunting hogs and coyotes outside deer season, but when hunting furbearers a light must be used that is visible for ¼ mile. In addition, there are rules from the U.S. Department of Commerce (known as ITAR and EAR regulations) that stipulate who can use and export some thermals and NV equipment.

However, many states do allow the use of night-capable optics, and unless you aren’t a U.S. citizen and don’t plan on exporting NV or thermals you likely won’t run afoul of ITAR stipulations. Nevertheless, it’s worth checking your state regulations regarding the use of night optics. There are also state-specific regulations regarding the use of night optics to scout or locate wounded game.

Night vision and thermal are both game changers, and no matter which you choose you’ll benefit from advanced technology that extends your time in the field. They also provide an effective method for controlling populations of certain animals, particularly feral hogs which are a nuisance to native wildlife. With more advanced technology and lower cost of own

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