Thermal vs Infrared Rifle Scopes | Differences Explained

A common misconception amongst shooters and hunters is that they think thermal and infrared scopes are the same thing – this is definitely not the case. Thermal scopes use heat, and infrared scopes use ambient light to produce images. I’ve had the privilege of hunting with both types of scopes more than I can count, and I can honestly say that it is vital that you choose the right one for your shooting applications. This article discusses thermal and infrared scopes and which is better for specific use cases. 

Thermal Rifle Scopes Explained

Thermal rifle scope

As the name suggests, a thermal rifle scope utilizes thermal imaging technology to detect heat signatures. Thermal scopes can provide vision in complete darkness, smoke, fog, and other obscure weather conditions.

The scope has infrared detector elements to identify infrared light emitted as heat by the objects. The heat signature is picked up by the elements and converted into an electrical signal. Then the signals are processed into data, ultimately forming a detailed temperature pattern known as a thermogram.

The color gradient witnessed on the display represents temperature differences between the object and its surroundings. Cooler objects appear darker and warmer objects appear brighter.

Infrared Rifle Scopes Explained

Infrared Rifle Scope

Infrared (IR) rifle scopes, more commonly known as night vision scopes, operate on a different principle than their thermal counterparts. IR scopes use image-enhancement technology to amplify any ambient light such as moonlight or starlight – creating a visible image.

An IR scope employs the use of a photocathode. This device is activated by incoming light (photons) and converted into electrons. These electrons are then amplified by the microchannel plate (MCP) in the image intensifier tube. Basically, when the electrons pass through the MCP, thousands more are released in the process.

Finally, the electrons hit a phosphor screen, converting them back into visible light. The IR scope also uses an IR illuminated to enhance the image quality and detail.

Thermal vs Infrared Main Differences

1) Wavelengths

These two scopes operate on different wavelengths of the electromagnetic spectrum (EM). Night vision devices or IR rifle scopes work with near-infrared wavelengths (approx. 0.7 – 1 micrometer). They amplify any available light (visible light and infrared light) to produce a visible image.

In comparison, thermal imaging cameras and the best thermal monocular detect mid-to-long-infrared radiation (8 – 14 micrometers), which any object above absolute zero emits. The heat emission is used to create the visible image.

2) Use Cases

Thermal scopes are, hands down, the better option for hunting at night. The ability of thermal cameras and scopes to detect living objects through fog, smoke, and thick vegetation enhances their versatility. Thermal imagers are also used for wildlife observation, human detection in search and rescue operations, and the military.


Infrared cameras and scopes are better suited for low-light conditions, such as varminting at dawn and dusk or during a full moon. IR is popular for night hiking and camping if using night vision goggles. Additionally, police and tactical enforcement use them when they need clear images in low-light conditions.

One thing I came to learn about infrared and thermal scopes is that an infrared scope is much more durable than a thermal scope. If you are thinking of taking one on a rugged expedition, then the infrared scope is better suited for the job.

3) Low Light Performance

The most important thing about IR scopes is that they require ambient light to produce visual images. An Infrared illuminator can help infrared scopes operate in near-total darkness, but then the image quality is not the best.

However, in low-light conditions, a night vision scope provides more detailed imagery than a thermal imager – making them more suited for varminting when you need to rely on fine detail recognition before taking a shot.

As already mentioned, thermal scopes do not require any form of light to function because they rely on heat. This enables you to use a thermal scope in complete darkness.

Main Benefits Of Thermal Scopes For Hunting

1) No Light Is Needed

The main benefit of using a thermal scope is the fact that you don’t need any light. This gives you a major advantage when hunting in various lighting conditions, such as twilight hours, moonless nights, dense vegetation, fog and smoke. Even a thermal monocular can be great for low light hunting!

2) Has Great Range For Spotting Animals

Thermal scopes can detect heat signatures from a considerable distance. This enables hunters to spot game from afar, reducing the probability that you scare them off or they pick up your scent.

3) Provides Visibility Through Dust, Smoke & Fog

Unlike infrared imaging and traditional scopes, thermal cameras and scopes can see through various types of environmental obstructions. This is because they rely on heat instead of light to detect animals.

Therefore, dust, smoke, or other particles do not significantly reduce the scope’s effectiveness, enabling hunters to hunt in diverse and sometimes challenging weather conditions.

Main Benefits Of Infrared Scopes For Hunting

1) High Image Quality

Infrared scopes are renowned for having a crisp image quality. Their method of creating images (amplifying existing light into detailed images) enables these scopes to produce more defined and recognizable images of animals.

As mentioned, this is incredibly important when hunting or varminting – the last thing you want is to shoot the wrong animal.

2) Makes Animals Visible In Low Lighting

Although not as effective as an infrared thermal imager, a night vision device still enhances visibility in low-light conditions such as dusk, dawn, and twilight hours. This dramatically expands the opportunity for hunting because many animals are more active at night, especially Night vision for varmints like hogs.

3) Compatible With Any Imaging System

Infrared scopes can be used with basically any optical imaging system, either as a standalone device, attachment to a standard scope, or integrated into other devices such as cameras and binoculars.

Frequently Asked Questions

Is IR or thermal better?

An IR is basically a visible light camera, which means it still requires some sort of light source to create images. In comparison, a thermal camera only requires heat to produce an image. However, an IR can create more defined images and is more durable. Ultimately it comes down to your use case and budget.

Does infrared mean thermal?

No, a thermal imaging camera uses heat to produce an image. In comparison, infrared or night vision devices detect visible light to create an image.

Can you see snakes with thermal imaging?

Yes, although snakes are reptiles, they still emit a heat signature and hence create a visible thermal image.

Does the US military use thermal or night vision?

The US military uses both night and thermal vision. However, the exact situation for using each may differ and depends on the unit's preference.

Final Thoughts

While these two might seem the same, thermal scopes rely on heat to create pictures, and infrared scopes need a source of infrared and visible light to create images. Each of these two imaging devices has a specific use case where they excel – thermal scopes work better in no light, and night vision devices are better for dusk, dawn, or rain. Ultimately, it comes down to your own preference and budget, as thermal scopes are considerably more expensive than infrared scopes.

About the author

Patrick Howard

I have been working as a gunsmith for 20 years. Rain, fog, moisture, high temperature, or even snow are all the things a product must withstand in order to be recommended by me.

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