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How To Choose A Thermal Rifle Scope – ATN specialist recommendations

The Mars 4

The Mars 4

Thermal rifle scopes have become much more accessible as technology and manufacturing costs have reduced, reducing consumer prices. Despite this reduction, thermal scopes are still a significant investment for a hunter, and with the wide variety on the market, how do you ensure you choose the best scope for your use and budget? Our ATN experts guide you through thermal scope technology and advise on what to consider before purchasing. They also suggest a couple of thermal scopes from the ATN range that will meet the needs of both professional hunters and enthusiasts.

How does a thermal scope work?

The sensor in a thermal scope does not use light to create an image; it uses infrared radiation. All objects emit an amount of infrared radiation that corresponds to their temperature. The thermal sensor will sense the differing temperatures and apply shades of grey or colour to depict each temperature. The result is a heat picture showing warm objects like people or animals in lighter colours of red and yellow and cooler objects like trees, grass, and buildings in darker shades of blue or dark grey.

When do you need a thermal scope for your rifle?

Security, fire, police, and defence personnel use thermal imaging to identify people who are difficult to spot using visible detection methods. When people hide in the undergrowth, are obscured by smoke, or are lost in the fog, thermal imaging disregards the camouflage. It uses the temperature of the individual to highlight them against the background.

It’s this capability that makes thermal rifle scopes so invaluable to the hunter. Here are some of the benefits of using a thermal scope when hunting:

  • Thermal scopes are passive technology that does not alert prey to the hunter’s location.
  • The prey can be standing or lying very still in long grass, fog, or behind foliage, and thermal technology will indicate their position.
  • On a moonless night when normal scopes might pass over a still animal, its heat radiation will betray its presence.
  • The game detection range of thermal scopes exceeds that of ordinary and night-vision scopes.
  • A thermal scope will indicate residual heat of a warm object, assisting in tracking game.

Thermal scopes become a hunter’s scope of choice when the area has considerable foliage or crops, is experiencing bad weather, or the hunting occurs at night under a thick overcast sky or when there is no moon. As they are also fully functional during the day, a thermal scope gives a hunter a true night and day, all-weather capability.

Thermal or night vision scope?

Night vision technology creates a picture at night by amplifying the reflected and available light. This method of operation means that as the light conditions deteriorate, in bad weather, under a heavy overcast, or on a moonless night, the quality of the picture also deteriorates. Night vision technology is unable to create a picture in complete darkness.

Thermal imaging technology does not rely on light to operate and instead uses heat differentials to create a picture. Therefore, the conditions that make night vision scopes less effective or inoperative do not affect thermal scopes. The thermal scope will continue to paint a temperature picture, revealing the game.

Parameters to consider when choosing a thermal scope

Once you have decided on purchasing a thermal scope, a hunter should consider a range of parameters to allow comparison between different scope models and to gauge each thermal scope’s suitability for their hunting needs.

Scope magnification

As with ordinary scopes, your choice of thermal scope magnification links to the field of view you require, the size of your game, and the range over which you’ll be shooting. Lower magnification scopes give you a wider field of view, so they’re great for allowing you to track game that is on the move. Higher magnification is great for stationary game or game at long distances.

Given that most hunters don’t seek only one type of game, a variable magnification scope is ideal. For shorter ranges, recreational shooting and deer, a 1-10x or 2-8x thermal scope would be ideal. A 1.5-15x or 4.5-18x thermal scope will meet your needs when shooting over longer ranges and larger game. However, when considering magnification, you must also consider the thermal sensor’s resolution, which we’ll discuss next.

Thermal scope sensor resolution

The quality of a thermal sensor is decided by its resolution. Like in a digital camera, the greater the number of pixels that make up a sensor, the more detailed the image is. Thermal sensors are currently available in five resolutions:

  • 160 x 120
  • 320 x 240
  • 384 x 288640 x 480
  • 1280×1024

Of these, 384 x 288 and 640 x 480 are found in most high-end thermal scopes, with 1280 x 1024 sensors available for defence purposes but largely out of reach of recreational shooters due to rarity and cost.

Bear sensor resolution in mind when choosing your scope, as while the higher resolution sensor adds almost 50% to the cost of your scope, if you need greater detail, particularly at higher magnifications, choosing the 640 x 480 will offer a markedly improved sight picture to aid target identification.

Display resolution

The highest resolution thermal sensor is immaterial if the display resolution fails to capitalise on those capabilities. Check that the display is capable of high definition, with a specification of at least 1280 x 720p. A high-definition display combined with a high-definition thermal sensor ensures no loss of image resolution when magnification is dialled up to its highest setting.

Sensor refresh rate

The refresh rate of your scope refers to the number of times the image is refreshed in one second. Manufacturers will refer to this in frames per second (fps) or Hertz (Hz). Ensure the thermal scope you are thinking of buying has a minimum of 50 fps or 50 Hz. Anything less than that will provide a disappointing and dragging image when your target moves.

Reticle pattern

Each hunter will have a preference for reticle type, and the thermal scope manufacturer should offer you a range of reticle patterns. A Mil-Dot reticle should be among the options for target shooters or those hunting over long ranges. The higher-quality thermal scopes will also offer a scalable reticle, allowing the shooter to program the variance between hash marks on the Mil-Dot reticle. They will also offer a simple and reliable method of zeroing the scope.

DRI Ranges

An important feature of thermal scopes is the distance over which they work. DRI refers to the ranges over which detection, recognition, and identification are possible. Detection refers to an ability to see that there is a warm object in the field of view; however, the distance makes it impossible to discern any information on the object. Recognition refers to the ability to tell whether the object is a human or an animal. Identification refers to clearly identifying the game before taking a shot. The quality of the thermal sensor will dictate the maximum distances over which each is possible, with prospective purchasers needing to clarify the capabilities of each scope under consideration to allow an accurate comparison.

Battery Life

When choosing a thermal scope, pay attention to the battery life you can expect. The last thing you need is to find your scope powering down mid-hunt. The battery in a good consumer-level thermal scope will provide a minimum of seven to eight hours of use, and military-grade scopes will run for ten or more hours.


Be sure to check the manufacturer’s warranty length before you set your money down. If something goes wrong with your scope, you must be sure the manufacturer will back it. Most thermal scope manufacturers will offer three years, although some offer five-year extended warranties. It’s also worth checking the warranty is transferable, so if the scope is bought second-hand within the warranty period, the manufacturer will still honor their obligation.

Best ATN thermal rifle scopes

ATN is renowned for the quality and performance of its thermal scopes. With a range of 14 thermal scopes, ATN caters to professional hunters and hunting enthusiasts alike, with options to suit all user requirements and budgets. Our ATN experts have selected the two they consider to be the best of the breed.

ATN MARS 4 640 4-40X

The MARS 4 range of thermal scopes is one of ATN’s most advanced thermal scopes, designed specifically for the serious hunter. A fourth-generation 640 x 480 thermal sensor assures an optimum image quality even at the scope’s 40x maximum magnification. The MARS 4 also uses a fast refresh rate of 60 frames per second (60 Hz) to guarantee no laggy or dragging image when your game is on the move.

Multiple reticle patterns and colours are available for selection, including ATN’s signature smart MIL Dot dynamic reticle that adjusts with magnification changes throughout the entire range. The scope boasts an outstanding 16-plus hours of operation on its internal lithium-ion battery, and should there be an issue with your purchase, ATN offers a three-year peace-of-mind warranty.

The processing power of the MARS 4 is via ATN’s Obsidian IV Dual core processor that supports recording and automatically sharing your hunting action on social media due to a recoil-activated video feature. Other capabilities include a ballistic calculator, a one-shot zero functionality, a smooth zoom feature, and an electronic compass.

ATN MARS LT 320 5-10X

The MARS LT range of thermal scopes is ATN’s production series of lightweight scopes designed for hunting over close ranges. This 320 5-10x scope gives you all the premium features expected in a hunting scope without peripheral options, making the scope more affordable and lighter at 650 grams. The LT 5-10x uses a 320 x 240 12µm sensor, giving an image resolution perfect for close-range hunting. Like its high-powered sibling, the sensor operates at a 60Hz refresh rate and is coupled with a high-definition display operating at 1280 x 720p to ensure optimal image quality.

Multiple reticle patterns are available, with the choice of white hot or black hot colour modes. The LT 5-10x gives more than ten hours of continuous operation on a full battery charge, with USB charging capability. There is also an option of adding an extended power kit to give up to 22 hours of continuous use. The scope’s body is hardened aluminium alloy designed to resist the recoil of heavy calibre rifles, and it comes with the standard ATN three-year warranty period.

Lower price does not mean lower spec, with the same one-shot zero capability of the MARS 4 range and a detection range of over 1600 meters. Recognition occurs at 710 meters and identification at 415. The LT 5-10x is weather resistant and attaches to your rifle using standard 30mm rings, giving you a 3-inch eye relief. This thermal scope is the lightest in the MARS range, designed to be fitted to platforms like crossbows and air rifles where weight and size are critical issues.


As thermal technology has become cheaper, thermal scopes have become more accessible to everyday hunting enthusiasts. Yet, prices are still considerably more than those of a standard rifle scope; therefore, prospective purchasers need to understand which features and capabilities they need and are available before deciding. In this article, our ATN experts have given you some points to consider. They’ve also suggested two thermal scopes they consider the pick of the bunch for both professional hunters and hunting enthusiasts. ATN leads the way in manufacturing highly sensitive thermal scopes. We offer an extensive range to suit every hunter’s needs, with all purchases backed by experts available to answer your questions or support your selection process.