← All units
Calculated from the sensor's pixel pitch and the lens focal length, for clear air. 
How far you can see a person
80 m make out detail130 m tell what it is521 m spot it┆ maker’s claim
501002005001k2k5k m
Guide quotes 1,300 m, 2.5× our figure, because makers usually measure against a person’s full height rather than their width. Why the numbers differ
GuideHandheld monocular · 400-class
Guide TE421
- Approx. price
- ~$949
- Sensor
- 400×300 · 12 µm
- Lens
- 25 mm · 1.9×
- Weight
- 10.4 oz
Buy from Guide
Price and availability on Guide’s site may differ.
Best for
Walk-and-scan glassing from a jacket pocket
01Specifications
As published by Guide. Sources: guideir-thermal.com, guideoutdoor.com (page lists 295 g, 11.11 oz; oz taken from grams).
- Sensor
- 400×300
- Pixel pitch
- 12 µm
- NETD
- 25 mK
- Refresh rate
- 50 Hz
- Lens
- 25 mm
- Digital zoom
- up to 7.6×
- Field of view
- 11° horizontal
- Display
- 800x600 AMOLED
- Claimed detection
- 1,300 m
- Claim basis
- unspecified
- Run time
- 5 h
- Battery type
- Internal Li-ion
- Weight
- 10.4 oz
- Length
- 6.1″
- Records video
- Yes
- Wi-Fi
- Yes
- IP rating
- IP67
- Warranty
- 5 years (10 years on sensor)
- Approx. price
- ~$949
02Pros and cons
From the published specs, not owner reports.
For it
- Light at 10.4 oz, 27th-lightest of the 112 handhelds here
- Waterproof (IP67), survives a dunking
- Records video and connects to a phone app
- Warranty: 5 years (10 years on sensor)
- ~$949, well under the ~$1,995 typical for handhelds here
Against it
- Built-in battery, so no swapping in the field, and only 5 h of it
- No rangefinder, so you judge distance by eye
- Zoom past 1.9× is digital and gets blurry
03Compare the TE421
04Related units
BurrisHandheld monocular
Burris BTH35 v3
Est. detection
729 m
Maker’s claim
1,000 m
- Sensor
- 400×300
- Pitch · Hz
- 12 µm · 50
- Lens
- 35 mm
22 oz~$2,160
AthlonHandheld monocular
Athlon Cronus ATS 35M-400
Est. detection
729 m
Maker’s claim
not published
- Sensor
- 400×300
- Pitch · Hz
- 12 µm · —
- Lens
- 35 mm
12.3 oz~$1,875
AthlonHandheld monocular
Athlon Cronus ATS 35ML-400
Est. detection
729 m
Maker’s claim
not published
- Sensor
- 400×300
- Pitch · Hz
- 12 µm · —
- Lens
- 35 mm
LRF · 14.8 oz~$2,375