Guide IR TD420 product image

Guide IR TD420

The TD420 is a thermal monocular made by Guide IR and is part of the TD series.


The TD420 packs a quality 25mm f/1.1 lens to capture thermal radiation. The field of view (FOV) on this thermal monocular reads 10.4 x 7.9 degrees. It's equipped with a 4x digital zoom to capture additional details. The exit pupil diameter is 12mm.

Inside the housing of the TD420 you'll find the (uncooled, 12µm) 400 by 300px sensor with a refresh rate of 50Hz. The NETD (Noise Equivalent Temperature Difference) of this thermal monocular is <50mK and it's operating between the 8µm and 14µm wavelengths.

The dimensions of this thermal monocular are 150 x 40 x 70mm (length/width/height) and weighs in at 350g. This device is rated IP66. It can withstand dust, shocks and water (splashes). Operating temperatures range between -10°C and 50°C.

The TD420 can be used for surveillance missions and hunting.



  • Small and Lightweight body
  • HD LCOS Display (1280 × 960 pixels)
  • 2 seconds startup time
  • Long Battery Life
  • Laser Pointer
  • PiP (Picture in Picture) mode
  • Five color palettes
  • WiFi Streaming


Lens25 mm
Diopter adjustment-4 +2
Exit pupil diameter12 mm
Optical zoom2.4 x
Digital zoom4 x
FOV (h/v)10.4 ° / 7.9 °
Thermal typeUncooled
Sensor resolution (h/v)400 pixels / 300 pixels
Pixel pitch12 µm
Sensitivity50 mK
Spectral range8 µm / 14 µm
Display resolution (h/v)1280 pixels / 960 pixels
Refresh rate50 Hz
Image polarityBlack Hot, White Hot, Red Hot, Iron Hot, Blue Hot
Output screen colorFull color
Video formatsAnalog video
Startup time2 seconds
Package contentsBattery charger, Single 18650 battery, USB Type-C cable, Lens cap, Wrist strap, Carry bag, Quick start guide
Dimensions (l/w/h)150 mm / 40 mm / 70 mm
Weight350 g
Number of batteries1
Battery life7 hours
Law enforcement
Search & rescue
Fire fighting
Operating temperature-10 °C / 50 °C
Storage temperature-30 °C / 60 °C
Environmental ratingIP66

DRI Ranges

DRI stands for Detection, Recognition and Identification and is based on the widely used Johnson's criteria.

  • Detection Detect if an object is present
  • Recognition See what type of object it is (i.e. person, vehicle, airplane)
  • Identification For example see if someone is a friend or foe
Detection Recognition Identification
Rabbit 375 meters 93 meters 46 meters
Person 1319 meters 329 meters 164 meters
Vehicle 3194 meters 798 meters 399 meters

Please note that these values are calculated, always consult the manufacturer for official range numbers.

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