Guide TE421 Compact Thermal Monocular

Scanning a field for coyotes through a thermal riflescope means swinging the rifle over everything you look at. A handheld does the looking instead, and the Guide TE421 is the 25 mm model of Guide's pocket-sized TE series: a 400 × 300, 12 μm sensor rated ≤25 mK behind a 25 mm F1.0 lens you focus by hand. Its detection range is rated at 1,300 m (1,400 yd).

Key Features

• More pixels on the target. Against the TE211, the TE421 has 2.4 times the pixels (400 × 300 against 256 × 192), and each pixel spans 0.48 mrad (12 μm ÷ 25 mm), about 4.8 cm at 100 m, where the TE211's 10 mm lens gives 1.2 mrad. The field of view is 11.0° × 8.2° (19 × 14 m at 100 m) from a 1.9x base magnification.
• Manual focus, adjustable eyepiece. Focus is manual: rotate the lens until the image is sharp at the distance you are watching. The eyepiece diopter adjusts from -5 to +5, and the eyepiece, with 25 mm of eye relief, is designed to reduce eye fatigue.
• One button, one ring. Turning the ring opens the menu and a press of the button selects. The button's short press can be set to zoom, photo, video, palette, calibration, menu or screen-off.
• Zoom and image tools. Digital zoom steps through 1x, 2x and 4x (1.9x to 7.6x). Hot track marks the warmest point, and three scene modes (Natural, Enhance, Highlight) work with seven palettes.
• Range estimates without a laser. The TE421 has no laser rangefinder. Its stadiametric tool estimates distance from two lines on the screen and the target's assumed height.
• Recording and the TargetIR app. Photos and video with sound go to 16 GB of built-in storage. Dual-band Wi-Fi (2.4 and 5 GHz) sends the live image to the TargetIR app, which can also run the monocular and install firmware updates; the Wi-Fi's maximum transmission distance is rated at 26.5 m.
• Built-in battery, quick charge. The battery is rated at 5 hours, and a 10-minute quick charge at an hour of use. A quick charging adapter comes in the box, and the USB-C port can also power the monocular.
• Sealed for weather. IP67, and rated to operate from -4°F to 122°F.

Who It's For

• Predator and hog hunters who scan before they shoulder the rifle. Find the heat signature with the monocular first, then go to the scope.
• Looking farther than a 10 mm monocular reaches. The TE421's detection is rated at 1,300 m (1,400 yd) against 500 m (550 yd) for the TE211 and the touchscreen TE211M. Those two cost less, need no focusing (their lenses are focus-free) and are rated for 6 hours.
• Buyers who also want a measured distance. The TD 633L adds a laser rangefinder rated to 1,000 m (1,090 yd) to a 640 × 512 sensor and a 35 mm lens, and runs a rated 10 hours on a replaceable 18650.

Accessories & Compatibility

• Remote. Guide's optional Bluetooth remote control pairs once Bluetooth is switched on in the menu.
• Mounting. The body has a tripod socket, and Guide Thermal USA's TE Series helmet mount, built for standard dovetail helmet receptacles, is compatible with the TE421.
• More options. Compare the Guide Sensmart thermal range or all our thermal monoculars.