Very simply a thermal scope (or any other type of thermal imager) detects infrared radiation that is emitted by all things living and nonliving and produces an image colorized according to the temperature of the radiation the objects are emitting. This means that thermal scopes/thermal imagers can work in almost all weather conditions and do not need any visible light in order to produce high-quality images for object detection.
Aren’t night vision and thermal imaging the same? No, although they both help you see in conditions adverse to normal human vision they are completely different with different strengths, weaknesses, and applications.
Lets first look at the biggest difference between night vision and thermal imaging. Night vision works just like your eyes do in that they detect light that is reflected off of objects. Night vision allows you to see in low light conditions because it amplifies the available light thousands of times more than your eyes can making night time seem like daylight. However, if there is no light even night vision will not generate an image, unlike thermal imaging.
A thermal scope uses a microbolometer (an uncooled thermal sensor) to detect infrared radiation with specific wavelengths that all objects emit. One of the biggest reasons that thermal imagers work so well no matter the light or weather conditions is because infrared radiation/light is emitted by all objects, unlike visible light that is reflected by all objects. The infrared radiation being emitted is detected by the microbolometer and translated into an image colorized by the different temperatures of radiation being emitted.
How can everything emit light/energy even non-living things? Biological objects (people, animals) and machines emit heat energy which is detected. Additionally, rocks, trees and other objects soak up thermal energy from the sun during the day and emit this energy during the night as the cycle continues.
So how is an image generated if all objects just emit heat? All materials emit heat differently so while you can touch a rock in the sun and feel that is it hot there are actually many different temperatures being emitted that we cannot distinguish which is where thermal imaging comes in. A thermal image is generated not by the temperature of the object but by the difference in temperatures that the object is emitting. Thermal imagers are very sensitive and can detect even a 0.01C temperature difference.
Thermal imagers are also not affected by objects with the same or similar contrast. Night Vision will have a hard time showing objects that are of the same or similar contrast because they rely on reflected light and cannot differentiate between objects temperatures.
Image produced with Night Vision Scope
Image produced with Thermal Riffle Scope
Armasight is the product line developed by the leader in the thermal imaging - FLIR. Armasight Zeus is one of the most compact and lightweight products in its class featuring the FLIR Tau 2 VOx microbolometer core. Specially developed for military use, law enforcement, as well as sporting activities, the scope has two versions - ZEUS 336 with 336 x 256 sensor and the more expensive ZEUS 640 with 640 x 512 sensor. The lens is made out of germanium, which is the preferred material for manufacturing high-quality lenses used in thermal imaging. FLIR's custom software platform has six digitally controlled reticle patterns (Dot 4 MOA, Line Dot, Cross Center Dot, Cross, Crosshair and “No Reticle”) available in 4 colors, ensures boresight retention and a high level of accuracy.
The thermal image is displayed in real time on 800x600 OLED display that has 8 adjustable brightness levels. Armasight ZEUS has a variety of use adjustable imaging controls: Smart Scene Optimization, Smart Contrast Enhancement, Digital Detail Enhancement and others. Digital zoom can be increased up to 4x without changing point-of-aim to point-of-impact relationship of the targeting reticle. This thermal rifle scope takes two CR123A batteries which is enough for about 4 hours of operations time. There is also an optional extended 4x CR123 re-rechargeable battery back, that will increase operational time up to 12 hours.
Overall, this is a very high-quality thermal imaging scope that is compact, lightweight and has the latest thermal core developed by FLIR. Warranty: 3 years Armasight warranty, 10 years on FLIR detector.
ATN Thor HD 384 has been designed and manufactured by ATN (American Technology Network). This is the entry-level thermal scope for hunting and sporting enthusiasts. The scope is equipped with the 384 x 288 sensor and all the "brains" of the scope is powered by newly released Obsidian Core. ATN's Obsidian core is responsible for running the UI as well as making over 1 billion computations per second. The result is a "smart" thermal scope that does a lot of work for you: ballistic calculator, smart range finder, calculating wind speed and direction, geotagging, e-baromter, e-compass and gyroscope, etc
Recoil Activated Video (RAV) will start recording as soon as you press the trigger and the video will be saved on external Micro SD card (up to 64GB capacity). Wifi streaming and controls are available when using ATN Obsidian App that is available for IOS and Android devices.
The scope is power by 4 AAA batteries that will provide up to 8 hours of operations time. The scope's body is water resistant, so you won't have to worry about it occasionally getting wet.
This is one of the best thermal rifle scopes for the money that will serve well sportsmen and hunting enthusiasts.
FLIR ThermoSight RS64 comes from the pioneer of the thermal imaging technology – FLIR. The ThermoSight R-series has a range of thermal scopes ranging from FLIR RS24 that has 240x180 resolution sensor, mid-range RS32 with 320x240 sensor and the FLIR RS64 - top of the line thermal scope with 640 x 480 sensor (30Hz refresh rate). All RS ThermoSight riffle scopes are compact and deliver class-leading performance!
RS64 is available with a 35mm lens as well as the 60mm lens. I suggest you go for the 60mm lens especially if would like a capability for long range hunting. The higher resolution sensor of the RS64 (4 times greater than the RS32!) as well as the 60mm lens will allow wider horizontal viewing angle (helpful with faster moving targets) and extend your maximum recognition range to 355 yards with 50 pixels on target.
6 color pallets are available on the RS64 (including Flir’s exclusive InstAler, which shows hottest objects in red), 3 reticle styles and 4 color options. The image is display on the 640x480 display with the 3-inch eye relief.
FLIR dependability and reliability is enhanced with internal shock reduction system (SRS-M), IPX7 water resistance body and a 3-year warranty on the scope and 10-year warranty on the internal sensor. Menu is accessible via top placed glove-friendly buttons. Power comes from a single CR123A battery that provides up to 4 hours of operational time.
If you want a top-notch thermal rifle scope, FLIR RS64 is one of the best options on the market today!
A Microbolometer (say that three times fast) is an uncooled thermal sensor that is made up of hundreds or thousands of individual pixels with each pixel having several layers. The top layer is the infrared absorbing material, followed by a gold contact, an electrode, and a reflector to ensure light that passes through the top layer is reflected back up to produce the best possible image. Finally, the bottom layer of the pixel is a readout circuit helping to generate the image. To ensure the infrared absorbing material is separated from the other layers of the pixel a gap is created between the IR material and the reflector using a substance that can be chemically etched away when the rest of the process is completed.
The finished pixel resembles a bridge with the IR detector being the bridge, the reflector being the water under the bridge and readout/image circuit the ground underneath the water.
As technology has continued to advance the image quality produced by microbolometers has continued to increase while the cost has also come down making thermal imaging available to many more people. Microbolometers are commonly available in 320x240 and 160x120 while lower resolution ones are cheaper they do not produce as high a quality image. For hunting, we recommend choosing at least a 320+ pixel thermal sensor ideally 640x480 especially if you will be shooting targets at distance.
This sounds expensive! Thermal scopes are more expensive than regular scopes however with the advent of the uncooled microbolometer as detection units as discussed above the costs have come way down. A cooled thermal imaging scope cost many times as much as today's thermal scopes and suffered from being very large, hard to operate and required a long amount of “cool down time” to be usable.
Just as your TV or monitor produces smoother pictures with a higher refresh rate (broadcast TV is typically 25 frames per second) thermal rifle-scopes with a higher refresh rate produce a smoother image as you track your target. As an example a 9Hz refresh rate means that the camera will refresh the image 9 times per second; while a camera with a 60Hz refresh rate sensor will refresh at 60 times per second. Typically, the higher the refresh rate the higher the cost of the scope.
Many scopes will also allow you to control the refresh rate which can drastically impact the battery life. Higher end thermal rifle scopes allow you to switch between 30Hz refresh rates and 60Hz refresh rates with the higher refresh rate draining the battery much faster but giving you a much smoother image.
The area where you will notice the refresh rate most is if you are shooting while moving and shooting at fast moving subjects. For instance, if you are sitting in the back of a truck and targeting running boars a low refresh rate rifle scope will likely not be enough as the image will lag and you will have difficulty hitting your target. The same scenario with a 30Hz or 60Hz refresh rate will be much better. If you will be shooting at fast moving targets and/or moving as you shoot, you will want a thermal scope with at least a 30Hz refresh rate. On the other hand, if you will be stationary and shooting at slower moving targets then you can save money and purchase a thermal scope with a lower refresh rate.
Most ATN ThOR HD rifle scopes have a 30Hz refresh rate sensors. Our best rated Armasight Zeus 336 has two versions - 30Hz and 60Hz refresh rate.
Does it matter what the thermal sensor resolution is in my thermal rifle scope? Yes! It matters a lot; just as with a regular visible light camera higher resolution produces clearer cleaner images that you can enlarge without the picture getting blurry. Some of the common resolutions for thermal rifle scopes are in order of quality 1024x768, 640x480, 320x240, 206x156, and 160x120.
One very important thing to make note of is the fact that you need to know what your thermal sensor resolution is not just the resolution of the scope. Some scopes will have an 800x600 display that is fed an image from the thermal sensor that is only 320x240 which means that your thermal image is never going to be as clear as the same scope with an 800x600 thermal sensor. Some lower end scopes with tout their high screen resolution while not mentioning that the thermal sensor is very low resolution. This allows them to sell their scope much cheaper but in the end, the quality is not as advertised.
As expected the higher the resolution the more expensive the thermal scope. Sensor resolution should be one of the areas that you spend the most time deciding on as a poor choice here will make your investment in your thermal rifle scope worthless. You should really go for the highest resolution that you can afford to buy even if that means forgoing some of the other features you want. A thermal rifle scope with poor resolution will drastically limit what targets and game you can shoot at.
As an example, the ATN ThOR 640x480 resolution will allow you to detect a human-sized target at 2,500 meters and completely identify the target at 600 meters. The Seek XR 206x156, on the other hand, will only allow you to completely identify a target at a little over 100 yards. You may be saying that complete identification is not a big deal but think about the situations you will be using your scope in; will you be hunting with a dog or other hunters? Are you completely comfortable that the pixilated image in your aiming reticle is the correct target?
If you know that you will be shooting short distances and will not have other animals or people around that could get caught in the crossfire then a lower resolution thermal rifle scope may be adequate.
Why should I be concerned about the detection range of my thermal rifle scope; it really going to be that much different than my visible light rifle scope? Yes, it is very different your visible light rifle scope shows you your target by showing the light that is bouncing or reflected off of your target. The thermal rifle scope shows you the target by detecting the different temperatures of the radiation/heat that your target is emitting. Because of this, visuals in a thermal rifle scope can degrade quickly over distances (unless you have a premium scope) resulting in you seeing a “target” but not being able to accurately identify the target which can cause severe problems.
A very high-quality thermal scope will allow you to positively identify the target at almost up to 1,000 yards while an entry level scope can limit you to 100 yards or less. You will want to make sure that you know what distances you will typically be shooting at before making your decision on what type of thermal imaging scope to buy.
The aiming reticle helps provide accurate targeting making your hunt more successful. Modern thermal rifle scopes have digitally controlled reticle patterns as well as reticle colors options. You might find, a Cross, Crosshair, Cross-Center Dot, Line dot, etc. Depending on conditions where you hunt and your target, you can adjust the reticle to give you optimal targeting. Reticle color options can also be important especially if you thermal rifle scope has various color patterns. Armasight Zeus provides electronic zoom reticle tracking. ATN ThOR HD on-screen reticle will guide you to optimal point of impact.
When choosing a thermal rifle scope, you will find that there are many lens options available. You might save money if you know what you need. So how do you choose one? Well, before you decide, you need to know some basics. There are usually three numbers indicated on scopes: variable optical zoom (2-16x, 8-32x, etc) and focal length (19mm, 35mm, 60mm, etc.). The first number is your adjustable optional zoom. You must pay attention to the second number as it will be tell you angle of view and magnification. The longer the focal length - the higher the magnification and the narrower the angle of view. Typically, longer focal length also means heavier lens and a more expensive scope.
Most thermal rifle scopes also include digital zoom or e-zoom, ranging from 2x to 6x.
Nobody wants to worry about the battery dying in a couple of hours during a hunt, so it is important to look at the average operational battery life as well as the type of batteries that a scope uses. ATN ThOR HD take 4 AA batteries, that is enough to power the scope for up to 8 hours and finding AA batteries is very easy. Every gas station will have them. Armasight Zeus is power by two CR123A batteries and has an option of extended battery pack. We recommended getting the extended battery pack as it will double your operational time so you wil have an extra 8 hours of run time.
Latest rifle scopes have an ability to record what you are seeing through the scope making it easy to capture best moments of your hunting. ATN ThOR line has a slot for Micro SD card (up to 64Gb capacity), making it easy to share and transfer images and videos to your PC. Some other rifle scopes, like the Armasight Zeus have video outputs as well as optional external HD video recorder. While as not as convenient as the ATN rifle scope, the options is there. If you are a techie, you will appreciate ATN's RAV option - Recoil Activated Video. The popular ATN ThOR 384 and ATN ThOR 640 have this option.
Thermal rifle scopes on today's market gained some nice connectivity features like built-in Wifi, bluetooth, video output, MicroSD card slot as well as video outputs. You should look at these functions as nice add-ons but not the primary factor buying a thermal rifle scope. Your thermal rifle scope is as good as the sensor and optics. ATN ThOR running the latest Obsidian core is packed with features like built-in Wifi, bluetooth and card slot for MicroSD. If you are someone who would like to have the latest software and apps, the ATN Obsidian app allows you to control your device and view live streaming on a mobile phone. It is fun and interactive. You can also view recorded videos on the app if your thermal scope is connected via Wifi to your phone.
Some thermal rifle scopes have a "clip-on" function, meaning that you do not need to dismount your daytime scope and re-zero it. Clip on rifle scopes mount in front of any daytime scopes. If you are interested in one of these, look into Armashight Apollo thermal imaging clip on systems They offer high-quality thermal rifle scopes with FLIR sensors and several lenses to choose from.
A variant of the “clip-on thermal scope” is the Inteliscope that is a self-contained rifle mount that includes an IR rifle scope and a gun camera that connects to your smartphone and uses your phone's screen to display the image. While these are inexpensive they do not have the features or range of a normal thermal rifle scope. For those of you looking to see what all the fuss is about for thermal rifle scopes or those of your with a very limited budget, the Inteliscope can be a great entry-level option.
Thermal rifle scopes are expensive and you should pay attention to the warranty length. Having a long warranty ensures that your investment will be covered in case of manufacturing defect. ATN warranty runs 3 years, while FLIR and Armashight give 3-year warranty on scope and 10 years on the thermal sensor. One of FLIR's strengths has always been their long warranty length.
Also, think about purchasing an extended protection plan if available many retailers such as Amazon offer these plans and they can make sense. Be sure to read the fine print and know what they will and will not cover to ensure it is a worthwhile additional purchase.
As you can see there are many different types of thermal rifle scopes at many different price points to satisfy pretty much anyone's budget and required feature set.
Our reviews are a great starting point for when you are narrowing down the best thermal scope for your budget and needs. The three most important things you need to ask your self when you are deciding on your thermal rifle are scope are:
If you are still not sure or just want to see how many different types of thermal rifle scopes there are you can find a large selection at great prices on Amazon.