Choosing Your First Thermal Scope

Choosing your first rifle scope graphic

Thermal rifle scopes are one of the most valuable tools a hunter could have due to their superior detection capabilities compared to day scopes. Just like any other thermal device, these scopes detect heat signatures by emitting an infrared signal. Then, the sensor converts the signal into a digital image, highlighting the heat signatures of targets. However, choosing your first thermal scope doesn’t come without its challenges. The technical aspects and oversaturation of brands and models can be overwhelming. In this blog you will find all the answers you need to pick the thermal scope that’s right for you.

Thermal Sensor

The thermal sensor is the most important component when it comes to choosing a thermal scope. It is the determining factor of image quality and object detail. There are three elements to consider when looking at a thermal sensor. They are resolution, NETD and frame rate

Resolution

The pixel resolution of a sensor dictates the image clarity. The higher the resolution the more detailed the images will be. Pixel pitch is another factor that affects resolution. It is the distance between the central point of two pixels in a infrared detector, measured in microns (µm). It influences base magnification and image quality. In this instance, the lower the pixel pitch, the better the resolution. Therefore, pixel resolution of a sensor should be at least 384×288 pixels. The ideal pixel pitch is between 12µm and 17µm.

NETD

Noise Equivalent Temperature Difference (NETD) is the measurement of the sensor’s thermal sensitivity. It highlights the smallest differences in temperature seen through the thermal device, measured in millikelvins (mK). Just like pixel pitch, the lower the NETD the better the sensor is at highlighting small temperature differences. The ideal NETD for thermal sensors, especially for thermal scopes is between <25mK and <40mK.

Hikmicro Stellar SH35 thermal scope
Hikmicro Stellar thermal image

Taken with the Hikmicro Stellar SH35

In the image above you can see the clear detail of the target and physical characteristics. This is due to the 384×288 pixel sensor with a pixel pitch of 12µm. In addition, the <35mK NETD highlight temperature differences, seen through the differing heat signatures of the target and background.

Frame Rate

Frame rate is the rate at which the pixels refresh on the display per second. For optimal images with minimal lag, a frame rate of 50Hz is best.

Detection Range

The next key area to consider when choosing a thermal scope is detection range. This refers to the maximum distance in which an object’s heat signature can be identified. It is dependent upon variable magnification and the size of the objective lens. The preferred detection range for thermal scopes is 1300 meters and above.

It is important to remember that the objective lens determines the field of view and magnification level. Therefore, the bigger the lens the greater the field of view and magnification. However, bigger lenses cause the scope to be heavier and more expensive.

Taking this into consideration, a thermal scope with a 35mm lens and 8x variable magnification is a good place to start.

Reticles and Zeroing

Reticles are patterns of lines displayed on the LCD or OLED screen of the thermal scope. Their role is to help the shooter aim with precision and accuracy. It is essential thermal scope shave at least 6 different reticles in multiple colours to suit user specific needs.

The zeroing in function of thermal scopes is another important aspect of thermal scopes. This feature allows shooters to adjust the position of the crosshairs to suit multiple different ranges. Once set, each range can be saved as profiles for future use. Scopes with built in laser range finders will make this process more accurate.

Pulsar Thermion 2 LRF

Pulsar Thermion 2 XQ50 LRF

The Pulsar Thermion 2 XQ50 LRF has 10 different reticles with 9 different colours and 5 zeroing in profiles. Users can customise their crosshairs and set calibrate them to their desired ranges.

Software Capabilities

As thermal scopes generate a digital image, the software needs to be up to industry standard. A 1024×768 OLED screen will yield high quality, smooth and clear images, highlighting important characteristics of targets.

The software functions and controls should also be relatively easy to use with little complications. Users should test how seamlessly they can transition between all the functions such as changing colour palettes or zeroing in. Likewise, boot up time should be evaluated as a three second boot up time is ideal.

It is also imperative that the thermal scope have at least four different colour palettes. These palettes aren’t just a filter, but serve to enhance the image in different conditions. The main colour palettes should include White Hot, Black Hot, Red Hot and Rainbow. Click here to find out about the functions of each different colour palettes.

Guide TU450 Thermal Scope
Guide TU450 colour palettes

Thermal images taken with the Guide Sensmart TU450 Thermal Scope

The Guide Sensmart TU Series thermal scopes come with 6 different colour palettes. It includes White Hot, Black Hot, Red Hot, Green Hot, Rainbow and Ultramarine.

Finally, WiFi streaming capabilities will be a huge advantage for hunting situations. It allows you to take photos and videos through a WiFi integrated app on a smartphone. Most importantly, it gives you the opportunity to have a second pair of eyes on the target through live streaming. This will make narrowing down a target more precise and accurate.

Mounting Options

Mounting rings allows the thermal scope to be fixed onto the rifle. A thermal scope that comes with 30mm mounting rings will simplify the process allowing for mounting without tools or equipment. These are compatible with tube style thermal scopes and generally come included. As for compact thermal scopes such as the Hikmicro Thunder Series, you will need to ensure it includes a picatinny rail mount.

In The Field

The next criteria to assess is how the thermal scope will perform when you are traversing through the outdoors. Different weather conditions will test your scope so it’s important to have all bases covered.

Ruggedness

Thermal scopes should have a minimum of a IP67 protection rating. This makes the scope waterproof, dust proof and protects against drops and shocks. This is essential for protection against the elements. Likewise, the scope’s operating temperature will determine if it will work in cold and warm temperatures. Therefore, you will need to ensure the operating temperature is between -25 °C to 50 °C.

Recoil

The recoil from high calibre rifles can damage the electronics of the scope and cause it to malfunction. So, it’s crucial that the scope is impact resistant. A recoil rating of 6000 Joules will allow the scope to handle high calibres such as .375H&H and 12-gauge.

Battery

A reliable thermal scope requires a battery life of between 7 to 10 hours. This will ensure they’ll last for extended periods of time in the field, especially at night. In general, thermal scopes have built in rechargeable batteries or removeable 18650 batteries. The 18650 batteries are beneficial as it allows users to replace them when the power runs out. Now the scope can be continually used throughout the day and night.

Hikmicro 18650 rechargeable battery
Hikmicro 18650 rechargeable battery

Conclusion

Choosing your first thermal scope doesn’t have to be overly complicated. Evaluating the criteria above should help understand thermal scopes and pick the one that suits you. Click here to view our full range of thermal scopes.

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