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ThermTec WILD 635L | Field Test

The ThermTec company entered the market of hunting thermal imaging devices in 2022 with its Cyclops series of thermal imaging monoculars. The first series of their thermal imaging devices (Cyclops, Vidar, and Ares) introduced some unique solutions in addition to some standard parameters that are either identical or very similar across most manufacturers within a certain generation of thermal imaging devices. This allowed ThermTec to attract attention in the market and among interested audiences.

The quality of the final products was also at a sufficiently high level, enabling the company to establish itself in a market already well-occupied by manufacturers from Europe (Pulsar), the USA (ATN), and China (Hikmicro, Iray, Guide, Pard).

ThermTec is a Chinese company primarily focused on developing night vision and thermal imaging devices for security purposes. As a result, they have developed a significant portion of their own technologies and software, necessary for the development of hunting thermal imaging products.

The challenge faced by Chinese companies entering the market for hunting-related products is their engineers’ lack of familiarity with hunting. The structure of Chinese society does not permit private firearm ownership, and the hunting traditions as known in Europe, North America, and Australia are not present there. However, representatives of ThermTec have collaborated with some of their sales agents in Europe, who, with their hunting experience, advise ThermTec’s development engineers on which features of their devices are actually useful, which are unnecessary, and which should be further developed and included in their products.

The Wild series of thermal imaging monoculars was developed with the help of European consultation, and we tested the Wild 635L model in a hunting area.

Technical Specification

The ThermTec Wild 635L is a thermal imaging monocular featuring a sensor resolution of 640 x 512 thermal pixels, a pixel pitch of 12 µm and thermal sensitivity with NETD <18 mK. Together with a 35 mm germanium lens and a fast aperture of F0.8, it delivers an image with a field of view of nearly 22 meters. The image is displayed on an AMOLED screen with a resolution of 1024×768 pixels.

The device, measuring 190x69x77 mm and weighing 505 grams, has an oval shape with a small laser rangefinder module positioned below the objective lens. Its magnesium housing is rubber-coated to provide a better grip and protection against scratches.

The combination of a large sensor, medium-sized lens, and 12 µm pixel pitch is becoming increasingly popular, as it delivers more than sufficient image detail for observation—even when compared to devices with a 50 mm lens. At the same time, the field of view and optical magnification are highly suitable for quick and comfortable observation of the terrain ahead, particularly when using the thermal monocular in the forest or at shorter distances.

  ThermTec Wild 635L
Sensor640×512 px
pixel pitch 12 µm
NETD <18 mK
Lens35mm / F0.8
MagnificationOptical magnification 2x Digital 1-4x
Field of view12.5°x10° 21.7 m / 100m
Detection range1800m
ScreenAMOLED HD 1024×768
Power18650 Li-ion Running time up to 8h USB – C connector
Dimensions190x69x77 mm 505 g
ProtectionIP67 -200 do +500
Video/image recordingResolution: 1024×768
Format: .mp4 / .jpg
64GB internal memory
ThermTec Wild 635L
ThermTec Wild 635L around the neck

Testing Process

The testing was conducted in early autumn, when most roe deer bucks still had their antlers. This allowed us to thoroughly assess whether the claimed NETD value of <18 mK truly enables the detection of small temperature differences. On several occasions, the hunting grounds were covered in fog, providing an opportunity to test the device under these challenging conditions for night observation tools. The game in the area predominantly consisted of roe deer, hares, and foxes, so most of the observations were focused on these three species. During the hunt, we had plenty of opportunities to evaluate the ergonomic features of the ThermTec Wild 635L and measure the battery life.

Image Quality

The technical specifications of the ThermTec Wild 635L thermal monocular do not stand out at first glance, as nearly all serious manufacturers of hunting thermal monoculars offer devices with identical core technical parameters. However, in practice, devices with nearly identical technical components can produce vastly different quality thermal images.

In our tests, it became evident that ThermTec has successfully combined its hardware with highly efficient software algorithms. The image produced was remarkably clear, with many details and uniform sharpness across the entire screen. The differentiation of temperature differences at the stated NETD <18 mK was so precise that we could clearly see the antlers of roe deer at distances exceeding 100 meters.

We estimate that wild boars could be evaluated for gender and age classification up to 100 meters away. Detecting living beings in the size of roe deer was possible throughout the hunting area, as the visible field of view was the limiting factor rather than the devices detection range. Even stationary roe deer could be identified at distances of 300-400 meters, while moving ones could be identified from even farther away.

Watch our video of thermal testing at different distances

In foggy conditions, the ThermTec Wild 635L performed admirably. When directly compared to a technically identical monocular from a more well-known brand, it detected living beings at noticeably greater distances while retaining some environmental details.

The device displays warm objects in black, white, and other colour palettes. All colour modes can also be displayed in an outline mode, which darkens the background and outlines the observed warm object with a border, to make it stand out on the screen. In truth, we did not find the outline mode particularly useful during our tests, as the regular image mode provided sufficient contrast between living beings and the surroundings.

The AMOLED screen with a resolution of 1024×768 represents a standard in this price range and performs excellently in the ThermTec Wild 635L. The screen displays a very clear image, free of unnecessary noise or edge distortion.

Digital zooming is available up to 4x and operates in 0.1x increments, both upward and downward. This allows for precise adjustment of the zoom level to meet specific needs while keeping image quality degradation manageable. Up to approximately 2.5x digital zoom, the image remained quite usable, but beyond that, it became increasingly pixelated.

We mostly kept the image settings (contrast and brightness) at a midpoint of 5/10, as recommended by the manufacturer. In foggy conditions, however, we increased the contrast to 8/10 or higher, which significantly improved detection range at the cost of a slightly less visually pleasing image.

Device Ergonomics

The ThermTec Wild 635L has an oval shape, a common design for thermal monoculars. While it is not among the smallest devices with a 35 mm lens, it remains compact enough to fit into a hunting jacket pocket. Even when combined with a traditional hunting binocular hanging around the neck, it did not significantly hinder movement in the field. It fits well in hand and offers a secure grip.

We paid particular attention to the device’s handling during testing in the hunting grounds, and ThermTec Wild monoculars feature a unique and innovative solution in this regard among thermal monocular manufacturers.

Most operations are controlled via a joystick located on top of the device. Moving the joystick left activates the laser rangefinder, while moving it right changes the color palettes and toggles the outline mode. Pushing the joystick forward and backward adjusts the digital zoom in 0.1x increments and navigates through menus. A short press calibrates the sensor or confirms a menu selection, while a long press exits submenus and returns to the main menu.

ThermTec Wild 635L
Buttons on ThermTec Wild 635L

Directly behind the joystick is a button for taking photos (short press) and recording videos (long press). In front of the joystick is a focus ring, which can be easily rotated with the middle finger. At the very front is the power button, which turns the device on/off (long press) or activates standby mode (short press).

When holding the device with the index finger on the joystick and the photo/video button, the middle finger can easily rotate the focus ring. Assuming the dioptre adjustment on the eyepiece has been correctly set beforehand, all essential functions can be controlled using two fingers of the hand holding the device to your eye.

This leaves the other hand free to handle a rifle, for instance, when resting it on a shooting stick or the edge of a hunting stand.

The eyepiece is equipped with a rubber shield to block daylight when using the device during the day. The lens cap opens to the side, is robustly constructed, and remains securely in position during use.

Although the laser rangefinder (LRF) module slightly protrudes from the device, it did not cause any issues, such as snagging, during our hunting sessions. The LRF module is practically unnoticeable during operation.

The neck strap can be attached in two ways. Traditional loops for the strap are located on both sides of the housing. Additionally, the device comes with a 1/4″ thread adapter at the bottom, featuring a loop for attaching both ends of the neck strap. This provides a single-point attachment for carrying the monocular. Users can choose their preferred attachment method based on their needs.

ThermTec Wild 635L
Attached neckstrap on ThermTec Wild 635L

Laser Rangefinder

The device’s LRF can measure distances up to 1,000 meters with an accuracy of +/- 1 meter and a minimum measurement distance of 10 meters. During testing, we set the rangefinder to continuous measurement mode, where it updates the distance every second or two at the point that LRF target box on the screen is pointing. This mode provided more accurate measurements than single-measurement mode, as distances stabilized after the device took three consecutive readings. Once stable, the measured distance could be considered accurate. Measurement can be stopped by a short-left press on the joystick.

Like most commercial laser rangefinders, the LRF was practically unusable in foggy conditions. It either failed to measure distances or displayed readings of just a few meters.

ThermTec Wild 635L
Laser rangefinder module on ThermTec Wild 635L

Power Supply and Battery

The ThermTec Wild 635L is powered by a standard 18650 lithium-ion battery without a button on the positive side – an essential detail to consider when purchasing spare batteries. The package includes two batteries with a capacity of 3200 mAh each. According to the manufacturer, a single battery can last up to 8 hours. During testing, the batteries lasted between 7 and 8 hours, depending on the frequency of using the laser rangefinder and outdoor temperature.

Mild autumn temperatures (~10°C) did not significantly challenge the battery’s performance. However, in harsher winter conditions, the runtime may decrease slightly. Even so, a combined usage time of approximately 14 hours with two batteries should suffice for most users.

For those requiring extended energy reliability, a wide range of 18650 lithium-ion batteries is available on the market. We recommend using reputable brands, with a nominal capacity of at least 3000 mAh and storing batteries in plastic cases, to prevent short circuits caused by contact with metal objects in a pocket.

The batteries can be charged via the device’s USB-C port or using the dedicated 18650 battery charger included in the package. The device can also be charged or directly powered during hunting sessions using a portable power bank.

Battery replacement requires some practice. Changing batteries at night on a hunting stand and while wearing gloves can be challenging. The battery compartment cover opens with a special lever, and the battery is seated relatively deep in the device. Therefore, a pull strap under the battery is essential for easy removal. Care must be taken to prevent the battery from accidentally falling to the ground when pulled out.

Included Accessories

When purchasing the ThermTec Wild 635L thermal monocular, the following accessories are included:

  • A soft carrying case,
  • neck strap,
  • hand strap,
  • USB cable,
  • battery charger and
  • two 18650 batteries.

Quick-start instructions are also provided.

The included accessories cover all essential needs. Only users requiring uninterrupted use beyond 14 hours will need to purchase additional batteries.

ThermTec Wild 635L
ThermTec Wild 635L

Connectivity

ThermTec provides the ThermTec Outdoor app for smart devices, which enables live image viewing, file transfer, device updates, and—for shooting devices—ballistic settings adjustments.

The connection between the monocular and smart devices (phones, tablets) proved stable under all conditions, even in environments with multiple available Wi-Fi networks.

Photos and videos can also be transferred via the included USB cable, with the device appearing as a removable storage medium on a computer.

Conclusion

The ThermTec Wild 635L thermal monocular stands out in its class. Along with excellent image quality, robust build, long battery life, and compactness, it offers a notable advantage: true one-handed operation.

While some manufacturers claim similar usability for their compact models, only ThermTec monoculars, based on our testing, allow real operation using just two fingers of the hand holding the device.

Although this feature alone may not convince loyal users of more established brands, it is genuinely practical and adds a highly useful bonus to a device that meets—and sometimes exceeds—market competition on all other criteria.

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