The 5 Best Thermal Monoculars of 2024 Everybody wants to know what goes bump in the night, even if it doesn’t bump and even if it’s not nighttime. Happily, thermal monoculars, a new and energetic category of gear, often identify what used to be invisible. They can help you see everything from human intruders on the other side of a fence, to coyotes and raccoons crouching in the dark, to a problematic wire in a household electrical outlet. We’re talking about monoculars, rangefinders, and cameras that use temperature variations, rather than visible light, to form images that can be captured as photographs or videos, or simply delivered to your eye to answer that ancient question: what’s out there? I’ve used this new class of “optics” over the past year to find newborn calves in a deadly blizzard, to find my ice-fishing buddies in the fog, to detect hidden electrical problems that might burn my house down, to hunt coyotes at midnight, and to finally even the odds on crop-raiding feral hogs. You could also use them to recover wounded game where it’s legal. Here are my picks for the best thermal monoculars, which range from flashlight-looking monoculars to small thermal viewers that connect to smartphones. Best Overall: Leica Calonox View Best Rangefinding: Pulsar Axion 2 LRF XG35 Best Entry-Level: FLIR Scout TKx Best Phone-Enabled: Xinfrared T2 Pro Best for Hunting: Zeiss DTI 3/35 How I Tested the Best Thermal Monoculars The field includes brand-new units that are just hitting the market this winter, others that I’ve tested over the course of the past year, and a few oddballs. My intention wasn’t to test every unit on the market, but rather handle a representative sample of products in order to provide a performance baseline. Also note that we’re not covering thermal rifle scopes in this particular roundup. I started by measuring attributes, assessing how far each thermal monocular could effectively detect a standard chemical hand warmer in the dark. I then used each unit on midnight-shift rounds of a calving operation to detect cows that wander away from the herd at night to give birth. The thermal mapping capability of these viewers can even show which cows are close to calving based on rising abdominal temperature. I also used the thermals on a series of sub-zero winter coyote and cottontail hunts to test their capabilities in the field and assess how their batteries would hold up to extreme cold. I enlisted the help of a digital (and thermal) native, Kaden Fossum, who independently tested all the units over the course of the fall and winter from his home in southeast Montana. Fossum measured the range, thermal sensitivity, and field-worthiness of each unit over several weeks of coyote hunting. Most of the videos and images that accompany each product review is from Fossum’s field work. Both Fossum and I assessed each unit’s imagery, both the type and utility of the palettes available and the resolution of the images. And we scored each unit’s ease of use and ergonomics.