The Armasight Operator 640 1-4x 35mm Thermal Clip-On sight includes a 35mm germanium objective lens. This does not provide the resolution of lenses measuring 50mm or larger, but proved ample for shooting nighttime raccoons from 50 to 150 yards.
Since consumer-grade thermal-imaging optics have become widely available to civilian shooters, I’ve auditioned a good number of units. This has included various units from a myriad of makers and offered at various price points. In this time, I’ve watched technology quickly evolve and prices slowly decrease relative to the image quality and performance now enjoyed. This has provided a solid feel for what separates viable units from those that are only marginally functional. All of my testing has occurred during Texas wild-hog culling forays while aiding long-time college friends in their continuing war on evasive hogs.
The Operator 640 from Armasight is easy to set up and intuitive to operate. The entire unit is controlled through just three tactile buttons: the round center button accessing the menu, and the front and rear wedge buttons helping run through pop-up options.
My latest experience involved a two-stop trip to West Texas, where severe drought had greatly depressed hog populations and pickings were slim. For that trip I chose Armasight’s Operator 640 Thermal Clip-On optic, which mounts in front of a standard daytime riflescope. I chose the Armasight for two reasons. First, Armasight is the only thermal-imaging weapon sight manufactured in the United States, including a majority of the interior components. This is important to me as a proud American. Second, I’d never tested a clip-on thermal unit and wanted to see what that approach was all about. This would allow me to utilize the Trijicon Huron 2.5-10x 40mm scope already mounted on my primary hog rifle, an AR-15 chambered in 6.8 Remington SPC, without requiring tedious sight-in and while maintaining a familiar reticle and eye relief.
The Operator 640 has a lot going for it. It is a robust and dependable unit, including a recoil rating up to 50 BMG due to its rugged, sealed aluminum-alloy housing with an IP67 rating (meaning it is highly water resistant) and gray anodized finish. It holds an ArmaCORE 640x480 Gen-3 12um thermal core with NETD <40 mK sensitivity and 60Hz refresh rate, translating into sharp images and no image interruptions in the heat of battle. It includes 1x native and 4x digital optical magnification through a f1.00 35mm germanium lens. The 1024x768 HD OLED display allows positive target identification and precise shot placement. The unit is capable of detecting man-sized targets to 1,300 yards to make locating distant hogs easier.
The battery compartment includes a hinged cap with a rubber seal, the sides showing clear instructions on how to properly install replacement batteries. Two CR123A batteries run the unit for four hours.
The American Defense Manufacturing quick disconnect mounting system (ADM QD) sets the unit 1.5 inches above rail height for optimal AR compatibility, and is easy to use. The Operator 640 is powered by two CR123A lithium batteries, which are easy to find, more affordable every year, and provide 4-plus hours of continuous run time at 68F/20C degrees. I like this feature, as rechargeable systems seem always to die at the worst possible moment, and this allows getting back into business in minutes. A battery-status indicator is included.
The image-focus wheel is located on the objective lens – instead of on the ocular bell like many thermal units. This placement proved natural to operate under pressure and while the weapon remained shouldered.
The Operator 640 weighs just 1.5 pounds, measures a compact 6.05x3.24x3.32 inches, and functions in temperature extremes between -40 and +122 degrees Fahrenheit (much wider than typical thermal units). The unit can be set up for a wide variety of color palettes to taste, and internal photo and video capabilities with playback are built in. Understand, though, the reticle will not appear in recordings, as it is housed in the daytime optic.
Best of all, the Operator 640 provides clean imaging and fast refresh rates for around $4K. Granted, that ain’t cheap, but there is no mistaking a calf or deer for a hog with this unit, even at extended distances or through fog or West Texas dust following gale-force spring winds.
The Armasight Operator 640 includes an ADM Manufacturing quick-detach Picatinny mount. This set the optic 1.5 inches above the rail and made adding and removing the unit a snap. It also provided dead-reliable repeatability.
The Operator 640 was designed for seamless integration, pairing with any 1-6x low power variable optic (LPVO) scope without re-zeroing, making it hunt-ready out of the box. I obviously used a scope with higher top-end magnification and an actual objective bell instead of a straight tube design, which did require a small amount of elevation adjustment to maintain zero through the Operator 640. The Operator 640 allows using the standard optic’s diopter focus, and the daytime scope’s reticle remains useful with all holdover subtensions.
Like other Armasight thermal optics, the Operator 640 is extremely easy to set up and operate, as it includes intuitive controls involving just three buttons located on top of the unit. That’s saying a lot coming from a technophobe like myself.
The Operator 640 by Armasight is a clip-on design that pairs with an existing riflescope. Straight-tubed low-power variable optics work best, requiring no sight-in after installation. Patrick used a larger optic, which paired just fine, but did require a couple of inches of corrections to achieve zero.
The unit’s secure, quick-detach mount allows nearly instant attachment and removal, allowing hunters to return to a straight daytime optic after sunrise, and go full thermal after sunset. That makes it more versatile than a dedicated thermal unit. Armasight’s USB-C connectivity allows streaming and viewing content on external devices like your home computer or television.
Armasight labels the Operator 640 ideal for tactical roles, though it works just as well for predator or hog hunting. The clip-on design didn’t perform quite as well as the high-end dedicated thermal units I’ve tested, but it provided all the usable resolution needed for positive target ID and precise shot placement. I like the objective-lens image focus, which proved natural to manipulate on the fly. The low-profile, tactile menu buttons are simple and remove any guesswork in the black of night.
The Operator 640 provides fast start-up time in the event, say, a hog runs across a ranch road unexpectedly. Shooters can cycle through the various color palettes with a long press of the center button, as well as multiple scene modes, such as Forest, Detect, Sky and Sea to tune performance to prevailing environments. The menus are responsive and, again, highly intuitive. A built-in digital compass and cant indicator are included. The unit housing includes a side Picatinny rail to mount red dots, lasers or weapon lights.
Experiencing a scarcity of hogs during my Texas visit, I used the Operator 640 to shoot a couple dozen nighttime raccoons. They’d set up housekeeping in my friend’s barn, where they were creating quite the mess and ripping into feed bags. While not as exciting as wild hogs, they did present more of a shooting challenge and made my host very happy.
The unit comes with a QD mount, USB-C cable, thermal zeroing target, two CR123A batteries, lens cloth, soft case and product manual. It includes a 3-year warranty with registration. To learn more, visit Armasight.com.
