640 Thermal Monoculars

Every monocular on this page is a handheld or head-mounted scanner built on a 640-class sensor. With the sensor settled, two things separate them: objective lens size, and whether a laser rangefinder is built in. Both are covered below, lens size first, since it changes more about how the unit handles.

Scanning Asks Different Things of a Sensor Than Shooting Does

A rifle optic has one job at the moment it matters: hold detail on a single animal you have already found. A scanner's job is the opposite — sweep a lot of ground fast, and pull anything warm out of a background that may be nearly the same temperature.

That is why sensor quality shows up differently in a handheld. You notice it less in how sharp a shape looks at 200 yards, and more in whether you spot the shape at all on a humid night when the ground has not cooled and everything reads flat. A 640-class sensor gives you more separation between a warm body and its surroundings, and that separation is what makes a sweep productive rather than frustrating. On a cold, clear night almost any thermal finds a coyote in a field. The nights that separate equipment are the other ones.

A 25mm 640 Monocular Is the Lightest Way to Carry Thermal

The smallest objective on this page keeps weight and bulk down and gives you the widest view per sweep, which is what you want when you are covering ground quickly or moving through it.

The RIX Stride ST6 Lite is the one 25mm unit here, and it is built to be worn rather than held — it mounts to a helmet or head harness and weighs well under half a pound, so it does not pull forward over a long night. The part that makes that work is true 1x base magnification: because it does not magnify, your depth perception stays intact and you can walk, climb, and handle a rifle while wearing it. That makes it a different tool from a magnified handheld — less useful for studying an animal at distance, far better for moving through country in the dark with both hands free.

A 35mm 640 Monocular Is the Everyday Choice

A 35mm objective is where most 640 scanners land. It sweeps a useful width of ground without being slow to work, and it stays light enough to carry all night. Six of the ten units here use one, and these three cover the range:

The Nocpix Lumi H35R keeps the package simple and the weight down while including ranging, which makes it an easy first scanner for someone adding a handheld to a rifle setup they already trust.

The Pulsar Oryx LRF XG35 sits on Pulsar's handheld platform with integrated ranging — a good fit if you already run Pulsar glass and want your controls, app, and battery habits consistent across the kit.

The AGM ReachIR LRF 35-640 pairs the sensor with a high-resolution OLED display and a removable 18650 battery you can field-swap, plus integrated ranging. Worth a look if long sits mean you carry spare cells rather than a power bank.

A 50mm 640 Monocular Reaches the Farthest in This Tier

A 50mm objective collects more signal and pushes usable distance further out, which matters on open ground where animals sit well back. The cost is a narrower view and more weight in your hand, so clearing the same field takes longer and holding steady takes more effort. Three units here use one:

The Pulsar Telos XP50 and Pulsar Telos LRF XP50 are the same optic with and without a built-in rangefinder, which makes choosing between them unusually clean — decide whether you want ranging on board, and everything else stays identical. Both sit on Pulsar's Telos platform, designed so components can be replaced or updated over the life of the unit rather than the whole optic going obsolete.

The AGM ReachIR LRF 50-640 is the third, pairing the larger objective with ranging and AGM's display and battery setup — the 50mm counterpart to the 35-640 above.

Eight of These Ten Monoculars Include a Built-In Rangefinder

Ranging is close to standard in this tier, so it is easier to describe by exception. Two units skip it: the RIX Stride ST6 Lite, where a rangefinder would work against the hands-free, walk-with-it purpose, and the Pulsar Telos XP50, which is the non-ranging version of an optic we also carry with ranging built in.

Everything else on this page has a laser rangefinder integrated into the unit, so a distance reading comes from the same device you are already holding. If you want to compare rangefinding scanners across every sensor tier we carry, not just 640, that has its own page.

Shop Thermal Monoculars with Laser Rangefinder.

A 640 Scanner Is More Than You Need for Close Cover

If your hunting happens inside a hundred yards in timber or brush, a 384-class scanner finds animals just as reliably and leaves money for other parts of the setup. The resolution gap shows up at distance and in poor conditions, neither of which describes short-range work in cover.

Reconsider too if you glass for hours at a stretch. Holding one eye open against an eyepiece for that long is its own kind of tiring, and a binocular spreads the work across both eyes and both hands.

And if there is no thermal on your rifle yet, start there. This is the tool that finds animals; it is not the one you shoot with, and the order matters.

Shop our Thermal Riflescope collection.

Shop our Thermal Handheld collection.

Frequently Asked Questions

Is a 50mm thermal monocular better than a 35mm?

Not better — different. The 50mm sees further; the 35mm sees wider and weighs less. Where animals hold at the back of a big field, the reach wins. On mixed or close ground, the wider view finds more because you clear terrain faster and are less likely to sweep past something. Buy the reach only if you regularly run out of it.

Is a 640 thermal monocular worth it over a 384?

The difference shows up as fewer unresolved moments rather than a visibly sharper picture. Side by side in good conditions, both look fine. What you notice over a season is how often you catch something at the edge of a sweep and can tell what it is without walking closer. If you hunt a handful of nights a year in easy weather, that is a hard case to justify. If you are out constantly, it compounds.

What magnification do I want on a thermal scanner?

Less than you would think. Scanning is about covering ground, and magnification narrows what you see per sweep, which slows you down and makes it easier to miss movement between passes. Low base magnification with the option to zoom once you spot something is the useful arrangement. A 1x unit you wear is a different case, since the point there is walking with it.

Can you mount a thermal monocular to a helmet?

Some are built for it and most are not. A unit designed for head mounting runs true 1x so the view matches what your other eye sees, and keeps weight low enough that it does not drag on your neck. Strapping a magnified handheld to a helmet does not work the same way — the magnification makes moving disorienting, and the weight tells on you within an hour.

Can I use a thermal monocular as a rifle scope?

No. These are observation devices with no mounting system, no reticle, and no recoil rating. Some brands make clip-on units that attach ahead of a day scope, but that is a different product built for the job.

How long do thermal monoculars run on a battery?

Runtime varies by unit and by how much you use ranging and recording. The more useful question is how the unit is powered: some take removable cells you can swap in the dark, others use internal packs charged over USB-C, and a few do both. If you sit long nights away from a vehicle, removable batteries matter more than any headline runtime figure.

Is a 640 monocular good for predator hunting?

It is the tier most predator hunters end up in. A coyote is a small heat signature that often stops well out and does not stay long, so anything that helps you resolve it quickly is worth having. Hogs are easier to spot but harder to count in cover, and a cleaner picture makes sorting a group simpler before you commit. Check your state's regulations before heading out.