Thermal rifle scopes have become indispensable tools for hunters, offering unmatched detection capabilities that far surpass traditional day scopes. Unlike optical scopes that rely on visible light, thermal scopes detect heat signatures by emitting an infrared signal, which is then captured by a sensor and transformed into a detailed digital image. This allows hunters to identify targets based on their heat emissions, even in complete darkness or harsh environmental conditions.
However, selecting your first thermal scope can be a daunting task. With an overwhelming array of brands, models, and technical specifications on the market, it’s easy to feel lost. Factors like resolution, detection range, magnification, and durability can all impact your choice, making it essential to understand each feature and its relevance to your specific hunting needs. In this blog, we’ll break down the key elements you should consider when choosing a thermal scope, helping you navigate through the options and find the perfect fit for your hunting adventures.
Thermal Sensor
The thermal sensor is the heart of any thermal scope, as it directly influences image quality and the level of detail you can discern. When evaluating a thermal sensor, there are three key factors to consider: resolution, NETD (Noise Equivalent Temperature Difference), and frame rate.
Resolution
The pixel resolution of a thermal sensor is a crucial factor in determining image clarity. Simply put, the higher the resolution, the more detailed and sharper the images will be, allowing you to identify targets with greater precision. However, resolution is just one aspect to consider — pixel pitch also plays a significant role in image quality.
Pixel pitch refers to the distance between the center points of two adjacent pixels on the infrared detector, typically measured in microns (µm). It directly influences both the base magnification and the overall image quality. In general, a smaller pixel pitch means better resolution, as it allows for more pixels to be packed into the same area, resulting in finer details and sharper images.
For optimal performance, a thermal scope should have a minimum sensor resolution of 384×288 pixels. As for pixel pitch, the ideal range lies between 12µm and 17µm. Smaller pixel pitches (closer to 12µm) provide higher image clarity, especially at longer distances, making it easier to detect and identify targets in various environmental conditions.
By considering both resolution and pixel pitch, you ensure that your thermal scope delivers the sharp, high-definition imagery needed for successful hunting or tactical operations.
NETD (Noise Equivalent Temperature Difference)
Noise Equivalent Temperature Difference (NETD) is a key metric that measures the thermal sensitivity of a sensor. It refers to the smallest temperature difference that the sensor can detect, and is typically expressed in millikelvins (mK). In simple terms, a lower NETD value indicates that the sensor can detect finer temperature variations, which translates to more detailed thermal imagery.
Just like pixel pitch, the lower the NETD, the better the sensor is at distinguishing subtle differences in temperature, especially in low-contrast or challenging environments. This sensitivity is crucial when hunting at night or in dense foliage, as it allows the scope to pick up even the slightest heat signatures, whether from animals or other objects in the field.
For optimal performance in thermal scopes, the ideal NETD range falls between <25mK and <40mK. A NETD below 25mK provides exceptional sensitivity, making it suitable for highly detailed target detection at longer ranges, while a value above 40mK may result in less precise thermal imagery.
Frame Rate
Frame rate refers to the number of times the image is refreshed on the display per second, typically measured in Hertz (Hz). A higher frame rate ensures smoother and more fluid thermal imagery, which is especially important when tracking moving targets. Low frame rates can cause lag, blurring the image and making it harder to accurately follow fast-moving objects, such as wildlife or suspects in tactical scenarios.
For the best viewing experience with minimal motion blur and lag, a frame rate of 50Hz is considered ideal. This ensures that the image is refreshed quickly enough to provide a smooth, real-time representation of your surroundings, allowing you to clearly identify and track heat signatures with ease.
Detection Range
When choosing a thermal scope, detection range is one of the most important factors to consider. This refers to the maximum distance at which the scope can detect and identify an object’s heat signature. The greater the detection range, the more effective the scope will be at spotting targets from a distance, which is especially crucial in hunting and tactical situations. The ideal detection range for most thermal scopes is typically 1300 meters or more.
The detection range is influenced by several factors, primarily variable magnification and the size of the objective lens. A larger objective lens allows more infrared light to enter the sensor, which increases both the field of view and the magnification power, ultimately extending the detection range. However, larger lenses also make the scope heavier and often more expensive.
For most users, a balanced thermal scope with a 35mm objective lens and 8x variable magnification offers an excellent starting point. This combination provides sufficient detection capabilities for most scenarios while maintaining a manageable weight and cost. Keep in mind that while a bigger lens improves performance, it may not always be necessary depending on your specific use case. If you primarily need close to medium-range detection, a smaller lens may be more practical.
Reticles and Zeroing
Reticles are essential aiming patterns displayed on the LCD or OLED screen of thermal scopes. They provide shooters with the necessary reference points to achieve precise and accurate shots. To accommodate various shooting preferences and conditions, it is crucial for thermal scopes to offer at least six different reticle designs, available in multiple color options, allowing users to choose the one that best fits their needs.
Equally important is the zeroing function, which allows shooters to adjust the position of the reticle to match specific target ranges. Once zeroed, these settings can be saved as profiles for easy recall during future use. Advanced thermal scopes equipped with built-in laser rangefinders further enhance the accuracy of this process, ensuring that the crosshairs are perfectly aligned for a given distance, thereby improving overall shooting precision.
The Feyachi TH-35 Thermal Scope offers versatility with 5 distinct reticle patterns available in 6 color options, allowing users to choose the best setup for different environments and shooting conditions. In addition, the scope features 5 customizable zeroing profiles, enabling shooters to fine-tune and save reticle adjustments for multiple ranges. This flexibility allows users to precisely calibrate their crosshairs to their preferred distances, ensuring optimal accuracy across various scenarios.
Software Capabilities
Since thermal scopes generate digital images, the quality of the software is just as crucial as the hardware in delivering superior performance. A 1024×768 OLED screen ensures high-definition, smooth, and clear images, allowing users to easily identify and assess key characteristics of targets, even in low-visibility conditions.
The software interface and controls should be intuitive and user-friendly, allowing users to navigate through various functions without hassle. It's essential that transitioning between different modes—such as adjusting color palettes or zeroing in on a target—be seamless. Additionally, boot-up time plays a critical role in overall efficiency; an ideal thermal scope should power up in three seconds or less to minimize delays in critical situations.
Equally important is the ability to customize the display with at least four distinct color palettes. These palettes are more than simple filters; they are designed to optimize image clarity in different environmental conditions. Commonly used color options should include White Hot, Black Hot, Red Hot, and Rainbow, each enhancing contrast and detail for specific scenarios, whether you're operating in bright sunlight, dark shadows, or varying temperatures.
Mounting Options
Mounting rings are essential for securely attaching a thermal scope to a rifle. For ease of use, a thermal scope with 30mm mounting rings simplifies the installation process, often allowing for tool-free mounting, making it quick and hassle-free. These rings are typically compatible with tube-style thermal scopes and are generally included with the scope, ensuring seamless integration.
For more compact models, such as the Hikmicro Thunder Series, it’s important to confirm that the scope includes a Picatinny rail mount. This type of mount is crucial for ensuring stability and compatibility with a wide range of rifles, providing a secure fit for compact thermal optics without the need for additional accessories or modifications.
Field Performance & Durability
When evaluating thermal scopes for outdoor use, it's crucial to assess their performance across various weather conditions and rugged environments to ensure they can withstand the challenges of the field.
A thermal scope should have at least an IP67 protection rating, ensuring it is waterproof, dustproof, and resistant to drops and shocks. This makes the scope highly durable and reliable in unpredictable weather. Additionally, the operating temperature range is critical; a good thermal scope should function effectively in both cold and hot conditions, with an optimal range between -25°C to 50°C.
Feyachi Thermal Scopes with IP67 protection and an operational temperature range of -20°C to 65°C, these scopes are built to handle everything from humidity to extreme temperature fluctuations, ensuring reliability in all weather conditions.
Battery Life
A reliable thermal scope should offer a battery life between 7 to 10 hours, ensuring consistent performance during extended field operations, especially during nighttime use. This duration is crucial for long hunting trips or surveillance missions, where constant power is essential.
Most thermal scopes are equipped with built-in rechargeable batteries or use removable 18650 batteries or removable rechargeable batteries . The latter offers a significant advantage, as users can easily swap out batteries when they run low, allowing for uninterrupted use throughout the day and night. This flexibility ensures that your thermal scope remains operational for as long as you need, without the worry of sudden power loss.
Conclusion
Selecting your first thermal scope doesn’t need to be overwhelming. By carefully evaluating the key criteria outlined above, you’ll gain a clear understanding of what to look for in a thermal scope and be better equipped to choose the one that best fits your needs and preferences. Whether you're focused on durability, performance, or ease of use, there's a thermal scope designed to meet your requirements.
Explore our full range of thermal scopes and find the perfect model to enhance your outdoor experiences.
