THERMAL GUIDE - Complete Thermal Imaging Buying Guide
The complete guide to thermal imaging for airsoft, milsim, and hunting: how thermal vision works, key specifications (NETD, resolution, pixel pitch), product categories explained, and our full catalog of AGM thermal devices — from pocket monoculars to professional rifle scopes.
Table of Contents
- How Thermal Imaging Works
- Key Specifications Explained
- Lens Size & Detection Range
- Product Categories Overview
- Thermal Monoculars
- Thermal Rifle Scopes
- Thermal Clip-On Systems
- Fusion Devices (Thermal + Digital)
- Thermal Binoculars
- Multi-Purpose: StingIR
- NVG + Thermal Fusion: F14
- Thermal vs Night Vision — Which to Choose?
- Thermal in Airsoft & Milsim
- Color Palettes & Scene Modes
- Accessories & Mounts
- Maintenance & Care
- Buying Advice & Common Mistakes
- Recommended Setups by Budget
1. How Thermal Imaging Works
Unlike night vision devices that amplify visible light, thermal imagers detect infrared radiation — the heat that every object above absolute zero (-273.15°C) emits. Warmer objects emit more infrared radiation, creating contrast that the device renders as a visible image.
The core of every modern thermal device is a VOx (Vanadium Oxide) uncooled microbolometer — a sensor array where each pixel is a tiny temperature-sensitive element. When infrared radiation hits a pixel, the VOx material changes its electrical resistance proportionally. This resistance change is measured, digitized, and converted into the thermal image you see on the display.
Key Technology Facts
- Detection band: 8-14 µm (Long-Wave Infrared / LWIR) — this is where objects at typical environmental temperatures emit the most IR radiation
- Detector type: Uncooled VOx microbolometer — operates at room temperature, no cryogenic cooling needed
- Image output: Digital — what you see is a processed image on an OLED display, not a direct optical view
- Works in all conditions: Complete darkness, fog, smoke, rain, through vegetation — thermal does not need any ambient light
- Cannot see through: Glass (blocks IR), thick walls, water (absorbs IR)
Unlike night vision (which is analog and instantaneous), thermal devices process each frame digitally, which introduces a slight delay. Modern devices at 50 Hz refresh rate make this imperceptible, but it is important to understand: a thermal device is essentially a specialized camera, not a direct viewing device.
2. Key Specifications Explained
Understanding these five specifications will allow you to compare any thermal device intelligently.
Resolution
The number of pixels on the detector sensor. More pixels = more detail and better image quality.
| Resolution | Total Pixels | Tier | Best For |
|---|---|---|---|
| 160x120 | 19,200 | Budget | Basic detection only |
| 256x192 | 49,152 | Entry | Short range, airsoft CQB |
| 320x256 | 81,920 | Mid-Entry | General use |
| 384x288 | 110,592 | Mid-Range | Versatile — great sweet spot |
| 640x512 | 327,680 | High-End | Detailed imaging, long range |
| 1280x1024 | 1,310,720 | Premium | Professional / flagship |
Sweet spot: 384x288 offers the best balance of image quality and price. For serious use, 640x512 is a significant upgrade in detail.
NETD (Noise Equivalent Temperature Difference)
Measures how sensitive the detector is to temperature differences, expressed in milliKelvin (mK). Lower is better. This determines how well the device distinguishes objects from the background, especially in challenging conditions (rain, fog, similar temperatures).
| NETD | Quality | Practical Impact |
|---|---|---|
| <20 mK | Excellent | Crisp detail even in rain/fog, fine temperature gradients visible |
| 20-25 mK | Very Good | Clear images in most conditions |
| 25-35 mK | Good | Adequate for standard conditions, slight loss in adverse weather |
| >35 mK | Basic | Usable but noticeable quality reduction in difficult conditions |
A device with 20 mK NETD will produce visibly cleaner images than one with 35 mK — particularly when the target temperature is close to the background. This spec matters most in rain, fog, and cold conditions where thermal contrast is reduced.
Pixel Pitch
The physical distance between pixel centers on the sensor, measured in micrometers (µm). Smaller is better for the same resolution — it means a more compact sensor with better detail-per-area.
| Pixel Pitch | Generation | Found In |
|---|---|---|
| 12 µm | Current (modern) | All current AGM products — higher detail, smaller sensor |
| 17 µm | Legacy | Older models (Explorator Pro, ASP TM) — larger pixels |
Today, 12 µm is the standard. It allows manufacturers to pack more pixels into a smaller sensor, resulting in more compact devices with better resolution. The 17 µm sensors are being phased out.
Refresh Rate
How many frames per second the device produces. All current AGM devices operate at 50 Hz — fast enough for smooth tracking of moving targets. Some budget devices from other brands may operate at 25 Hz, which causes visible lag when panning.
Display
Most AGM thermal devices use a 1024x768 OLED display (0.39"), which provides crisp, high-contrast images with deep blacks. The flagship Evolver uses a 2560x2560 display.
3. Lens Size & Detection Range
The lens size is one of the most critical choices when buying a thermal device. It directly determines magnification, field of view, and detection range.
| Lens | Base Magnification* | FOV (approx.) | Detection Range | Best For |
|---|---|---|---|---|
| 10-15mm | 1x | Wide | 300-600m | Scanning, CQB, awareness |
| 19mm | 1.5-2.5x | 9° x 7° | 800-900m | Short range, airsoft fields |
| 25mm | 2-3.5x | 7-10° x 5-8° | 1,000-1,200m | Versatile — general purpose |
| 35mm | 2.5-3.5x | 7.5° x 5.6° | 1,400-1,800m | Medium-long range |
| 50mm | 2.5-4x | 5-9° x 4-7° | 2,000-2,600m | Long range hunting/observation |
| 75mm | 3.5x | 5.9° x 4.7° | 3,500-3,800m | Extreme long range |
*Base magnification depends on resolution. Higher resolution sensors produce higher magnification at the same lens size.
Important: Larger lens = more magnification but narrower field of view. For airsoft at 10-100m, a 19mm or 25mm lens is ideal. For hunting or observation at 100-400m+, go with 35mm or 50mm. Do not over-magnify — too much zoom in a thermal sight makes target acquisition slower.
There is also a distinction between detection, recognition, and identification range (the DRI criteria):
- Detection: You can see something is there
- Recognition: You can tell it is a person vs an animal
- Identification: You can distinguish specific details (gear, posture)
Recognition range is typically 40-60% of detection range. Identification range is about 25-30% of detection range.
4. Product Categories Overview
Thermal devices come in several form factors, each designed for a specific use:
| Category | Use Case | Price Range |
|---|---|---|
| Monoculars | Handheld scanning, detection, observation | 509€ - 4,830€ |
| Rifle Scopes | Mounted on weapon for aiming | 995€ - 4,459€ |
| Clip-Ons | Attach in front of existing day scope | 1,210€ - 4,225€ |
| Fusion Devices | Thermal + digital CMOS combined | 1,981€ - 3,954€ |
| Binoculars | Two-eye observation, long range | 4,830€ - 8,860€ |
| Multi-Purpose | Handheld/helmet/weapon/clip-on | 3,265€ - 4,830€ |
| NVG+Thermal Fusion | Image intensifier + thermal overlay | 13,092€ - 13,310€ |
5. Thermal Monoculars
Handheld thermal devices for scanning, detection, and observation. The most versatile category — carry one in your pocket, scan an area, detect hidden targets. Not mounted on a weapon.
Taipan — Entry Level Pocket Thermals
The most affordable way to enter thermal imaging. The Taipan series are compact, pocket-sized monoculars ideal for beginners and as secondary scanning devices.
- 12 µm VOx sensor, 50 Hz refresh
- Multiple color palettes
- External power supply option
- 3-year warranty
Seeker — Mid-Range Pocket Thermals
A step above Taipan with 20 mK NETD — better sensitivity for more demanding conditions. 384x288 resolution with compact form factor.
Sidewinder — Premium Monoculars
Professional-grade handheld monoculars with 20 mK NETD, available in 384 and 640 resolutions. These are serious observation tools with excellent image quality.
ASP — Specialized Monoculars
The ASP-Micro is an ultra-budget 160x120 option for basic detection. The ASP TM35-640 is a capable mid-range monocular.
▶ Browse all thermal monoculars
6. Thermal Rifle Scopes
Thermal weapon sights designed to mount directly on a rifle for aiming. They include reticles, zeroing profiles, and are rated for weapon recoil. The most popular category for hunting and airsoft snipers.
Rattler V2 — Best Value Thermal Scopes
AGM's best-selling thermal scope line. The Rattler V2 offers excellent performance at competitive prices, making it the go-to recommendation for most buyers.
- 12 µm VOx detector, 50 Hz, 20 mK NETD
- 1024x768 OLED display
- Shot Activated Recording (SAR) — records when you fire
- Wi-Fi hotspot for smartphone control (AGM app)
- 10 reticle options, multiple zeroing profiles
- ADM Quick-Detach mount included
- 2x NE-4400 rechargeable batteries included
- 16 GB built-in storage, IP67 waterproof
- 1,000g recoil rated
- 5-year warranty
Rattler V1 — Original Series (Still Available)
The original Rattler line — still solid performers, available at reduced prices while stock lasts.
▶ View Rattler V1 scopes
Adder — Mid-Range Professional Scopes
A step above Rattler in build quality and features. The AdderV2 LRF model includes a built-in laser rangefinder.
- 12 µm sensor, 50 Hz
- Available in both aluminium and germanium lens options
- AdderV2 adds LRF and 15 mK NETD
Varmint LRF — Hunting-Focused with Rangefinder
Designed specifically for hunters with integrated laser rangefinder. The V2 versions add a ballistic calculator for precise holdover at range.
▶ View VarmintV2 with ballistic calculator
Secutor Pro — Professional Long-Range
Professional-grade thermal sights for serious long-range work. Superior build quality and optical performance.
▶ Browse all thermal rifle scopes
7. Thermal Clip-On Systems
Clip-on systems mount in front of your existing daytime scope, converting it into a thermal weapon sight. This is the ideal solution if you already own a quality day scope and want to add thermal capability without replacing it.
How Clip-Ons Work
- The thermal unit projects its image through a relay lens into your existing scope's objective
- 1x base magnification — your day scope's magnification is preserved
- Quick-attach/detach front mount system with adapters for different objective sizes (25-62mm)
- Zero is maintained between attach/detach cycles
- Compatible with day scopes up to 10x magnification
Rattler-C V2 — Modern Clip-On
The latest clip-on generation with 20 mK NETD, Wi-Fi, and video recording.
Rattler TC — Original Clip-On (Budget)
The original Rattler clip-on series — more affordable entry points. The TC19-256 is the most budget-friendly clip-on option available.
The optional eyecup accessory converts any Rattler TC35 or TC50 clip-on into a standalone thermal monocular or weapon sight — a 2-in-1 solution.
8. Fusion Devices (Thermal + Digital)
Fusion devices combine a thermal sensor with a digital CMOS camera in a single unit, offering multiple viewing modes: pure thermal, pure visible/digital, or a blended fusion view. This provides context that pure thermal lacks.
Fuzion LRF — Fusion + Laser Rangefinder
The premium Fuzion line with an integrated 600m laser rangefinder. Three viewing modes (thermal, visible, fusion), 12 µm sensor, 1920x1080 CMOS, built-in IR illuminator, Wi-Fi, and 16 GB storage.
Fuzion Standard — Fusion Without LRF
Same fusion technology at a lower price point, without the laser rangefinder.
When to choose fusion: Fusion is excellent for situations where you need both detection and identification. The CMOS channel provides detail and color that thermal alone cannot — you can detect a heat signature, then switch to visible mode to identify the target. The blended fusion mode overlays thermal signatures onto the visible image for the best of both worlds.
9. Thermal Binoculars
Two-eye thermal observation devices for long-range surveillance. More comfortable for extended viewing sessions than monoculars.
Voyage LRF — Fusion Binoculars with Rangefinder
Professional-grade thermal + CMOS fusion binoculars with integrated laser rangefinder. Available in 50mm and 75mm lens options for medium to extreme long-range observation.
Explorator — Premium Fusion Binocular
The Explorator FSB50-640 is a high-end fusion binocular with 640x512 thermal sensor and 1280x768 digital camera.
10. Multi-Purpose: StingIR
The StingIR is a unique product — an ultra-compact, ultra-light (220g / 7.8 oz) thermal device that can be used as a handheld monocular, helmet-mounted device, weapon sight, or clip-on. The Swiss Army knife of thermal imaging.
- 12 µm VOx sensor, 25 mK NETD
- 1024x768 OLED display
- Digital compass and inclinometer
- Multiple palettes: WhiteHot, BlackHot, OrangeHot, Rainbow
- Helmet mountable, Picatinny rail compatible
- CR123A/RCR123 or 18650 battery options
- 5-year warranty
11. NVG + Thermal Fusion: F14
The AGM F14 is the ultimate fusion device — it combines a genuine Photonis image intensifier tube (night vision) with a 640x512 thermal sensor in a single monocular. The thermal overlay is fused onto the NVG image, giving you the navigation ability of NVG plus the detection power of thermal.
Available in both P45 White and P43 Green phosphor. This is the top-tier option for operators who need both technologies in a single head-mountable package.
See also our Night Vision Guide for full NVG buying advice.
12. Thermal vs Night Vision — Which to Choose?
This is one of the most common questions we receive. The short answer: they are different tools for different purposes.
| Feature | Night Vision (NVG) | Thermal Imaging |
|---|---|---|
| How it works | Amplifies ambient light | Detects heat radiation |
| Needs light? | Yes (moonlight, stars, IR) | No — works in total darkness |
| Image type | Analog, natural-looking | Digital, processed heat map |
| Latency | Zero — real-time optical | Minimal (50 Hz digital) |
| Detection | Must visually spot targets | Heat signatures stand out instantly |
| Navigation | Excellent — see terrain, obstacles | Difficult — limited depth perception |
| Through fog/rain | Degraded — depends on light | Good — heat penetrates conditions |
| Through glass | Yes | No — glass blocks IR |
| Weight (head-mount) | Lightweight (PVS-14: ~340g) | Heavier (varies by model) |
| Battery life | 40-100+ hours | 4-11 hours typical |
| Best for | Navigation, CQB, fast movement | Detection, observation, holding positions |
| Price entry | ~2,300€ (Wolf-14) | ~510€ (ASP-Micro) / ~769€ (Taipan) |
When to Choose Thermal
- Holding positions / perimeter defense: Thermal excels — heat signatures pop out instantly, even through bushes
- Area sweeps / reconnaissance: Scan large areas quickly, detect hidden targets
- Budget-conscious: Entry-level thermal (Taipan at ~769€) is much cheaper than entry NVG (~2,300€)
- Adverse weather: Rain, fog, smoke — thermal maintains effectiveness
- Support/sniper role: Dedicated observation and aiming
When to Choose NVG
- Moving / navigating: NVG provides a natural view of the environment
- CQB / fast-paced: Zero latency, wide FOV, depth perception
- Extended operations: Battery lasts 40-100+ hours vs 4-11 hours
- Assault role: Head-mounted NVG with IR laser for target designation
The ultimate setup? Both. An NVG for navigation and an IR laser for CQB, combined with a thermal monocular or thermal weapon sight for detection and long-range engagement. Our NVG Guide covers the night vision side in detail.
13. Thermal in Airsoft & Milsim
Thermal imaging is increasingly popular in airsoft milsim events. Here is what you need to know for practical use.
Ideal Use Cases
- Night milsim events: Detect players hiding in vegetation, behind cover, or in dark buildings
- Perimeter defense: Scan treelines and open areas for approaching players
- Sniper support: Locate targets for a sniper team, then guide them onto target
- Building clearing: Detect heat through thin walls, locate players behind furniture
Practical Tips for Airsoft
- Distance matters: At airsoft ranges (10-80m), even a 256x192 / 19mm device will clearly show a human target
- Lens choice: For typical airsoft field distances (10-100m), a 19mm or 25mm lens is ideal — enough magnification without losing field of view
- Clip-on advantage: If you already have a quality scope, a clip-on lets you use thermal without changing your zero or setup
- Battery management: Carry spare batteries. Thermal devices consume significantly more power than NVGs. A powerbank can extend runtime via USB-C on most models
- Scan speed: Unlike NVGs where you see everything in your FOV, with thermal you need to actively scan — sweep slowly across the area
- Temperature equalization: In hot weather (35°C+), targets may blend into the background. Thermal works best when there is a temperature difference between the target and surroundings — cold nights are ideal
Recommended for Airsoft
Best value scope: Rattler V2 25-384 — 384x288 resolution, 25mm lens, 20 mK, all features, under 1,800€
Budget monocular: Taipan TM15-384 or Seeker 15-384 — both under 1,400€ with 384 resolution
Budget clip-on: Rattler TC19-256 — convert your existing scope for just 1,210€
14. Color Palettes & Scene Modes
All AGM thermal devices offer multiple color palettes to display the thermal image. The palette does not affect detection capability — it only changes how the image looks.
| Palette | Description | Best For |
|---|---|---|
| White Hot | Warm = white, cold = black | General use, most natural-looking, best for detail |
| Black Hot | Warm = black, cold = white | Bright backgrounds, reduces eye strain in urban settings |
| Red Hot | Warm areas highlighted in red/orange | Quick detection — heat sources pop out |
| Rainbow | Full color spectrum by temperature | Maximum contrast, technical analysis |
| Fusion | Grayscale base + red for hottest areas | Balanced detail with hot-spot highlighting |
Most users settle on White Hot for general use — it provides the most natural-looking image with good detail. Black Hot is preferred by some in bright or urban environments.
Additionally, some devices offer scene modes (like "Jungle" and "Recon") that adjust image processing parameters for specific environments — increasing contrast in vegetation or reducing noise in open terrain.
15. Accessories & Mounts
Essential accessories for your thermal setup.
Scope Mounts
Quick-release mounts for thermal rifle scopes — essential for maintaining zero and fast attach/detach.
Clip-On Front Mounts
Adapters that connect clip-on thermal units to your day scope's objective. Choose the size that matches your scope's objective diameter.
Eyecup / Monocular Converter
Converts Rattler TC35/50 clip-ons into standalone monoculars or weapon sights.
16. Maintenance & Care
Thermal devices are robust electronic instruments, but proper care extends their lifespan significantly.
Lens Care
- Germanium lenses (used in all thermal devices) are coated with an anti-reflective coating — never use regular glass cleaner or solvents
- Use a microfiber cloth with gentle pressure, or compressed air to blow off dust
- For stubborn dirt, use lens-specific cleaning solution designed for coated optics
- Always use the lens cap when the device is not in use
- Never point the lens at the sun — while it will not damage the sensor like with older cooled systems, it can degrade coatings over time
Battery Management
- Store batteries at 40-60% charge for long-term storage
- Avoid leaving batteries fully discharged — this can permanently reduce capacity
- Use only the manufacturer's recommended battery type (NE-4400, CR123A, 18650 depending on model)
- For extended field use, carry a USB-C powerbank — most AGM devices support external power
- In cold weather, keep spare batteries warm in a pocket — cold significantly reduces battery capacity
Storage
- Store in a dry, temperature-stable environment
- Use silica gel packets in the case to prevent moisture buildup
- If the device has been used in rain, allow it to dry thoroughly before storing
- Periodic power-on (every 2-3 months) helps maintain electronics in good condition
Firmware Updates
AGM periodically releases firmware updates via the Wi-Fi connection and smartphone app. These can improve image processing, add features, or fix bugs. Check the AGM app regularly for updates.
17. Buying Advice & Common Mistakes
Common Mistakes
- Buying too much magnification: A 50mm lens at 20m in airsoft is like looking through a straw. Match the lens to your actual engagement distances.
- Ignoring NETD: Two devices with the same resolution can produce very different images. A 384x288 sensor with 20 mK NETD will outperform a 640x512 with 40 mK in fog or rain.
- Choosing resolution over lens quality: A 384x288 with a quality 35mm germanium lens can be more effective than a 640x512 with a cheap 19mm lens for medium-range use.
- Forgetting about battery life: Thermal devices run 4-11 hours. Budget for spare batteries or a powerbank.
- Not matching the device to the role: A rifle scope is not a scanning device. A monocular is not a weapon sight. Choose the right form factor for how you will actually use it.
How to Choose
- Define your primary use: Observation? Weapon sight? Both? This determines the form factor.
- Set your budget: Be realistic. A quality 384x288 device is better than a stretched-budget 640 with compromised NETD.
- Choose your distance: This determines lens size. 19-25mm for short range, 35mm for medium, 50mm+ for long.
- Prioritize NETD and resolution: These matter more than zoom range or extra features.
- Consider the ecosystem: AGM devices share batteries, mounts, and accessories across lines. Buying into one ecosystem pays off long-term.
18. Recommended Setups by Budget
Under 1,000€ — Entry Level
A pocket thermal monocular for basic detection and scanning.
1,000€ - 2,000€ — Best Value
This is the sweet spot. At this price you get 384x288 resolution scopes or quality monoculars — enough for serious use in airsoft, hunting, and observation.
2,000€ - 3,500€ — Serious Equipment
Full-featured 384x288 scopes with LRF, or entry to 640x512 resolution. Excellent image quality and all the features.
3,500€+ — Premium & Professional
640x512 resolution scopes, professional-grade binoculars, and fusion NVG+thermal devices. The best image quality and detection range available.