Recoilweb: iRay RS75 Thermal Scope Review

Editor’s Note: This iRay RS75 thermal scope review was originally published by our sister publication, RECOIL. For more reviews of the latest guns and shooting gear, go to Recoilweb.com.

When 4K televisions dropped onto the scene in 2012, they had $20,000 price tags but shocked with eye-popping performance no one had ever seen before. For most folks, they were mostly proof-of-concept pieces to gawk at and wonder what tax bracket could actually own one. Fast-forwarding to today, now that technology is both commonplace and affordable. Like that 4K TV probably adorning your living room right now compared to the previous standard, the new iRayUSA RICO HD RS75 provides four times the resolution of any rifle-mounted thermal scope on the market.

And at $17,999, it’s beyond many peoples’ wallet.

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With the release of iRayUSA’s new optic, the thermal industry just heard the loud clunk of one Thanos-sized gauntlet being thrown down. Teeny, low-resolution sensors providing pixelated pig pictures are no longer cool or cutting edge. YouTube hunting videos can now go full screen without turning coyotes into Minecraft animals. Video-producing varminters with the spare cash now have a new level of flex — all of which sucks for mortals who are looking for a midrange or entry-level thermal, right? Nope.

Tech advancements come fast, and the RS75’s mere existence will drive down the price of so-called “normal” thermals, as well as kickstart an arms race for everyone to do it better. With “everyone” meaning both competitors as well as iRay themselves.

iRay RS75 Lens and Sensor

Bottom line up front: Every article you’re ever going to see about this optic is going to yammer on a lot about the sensor. The uncooled micro-bolometer sensor (the “eye” of the camera) that detects heat is 1280×1024. The big news is that’s four times bigger than formerly state-of-art 640 resolution scopes (there are twice as many of those little 12um pixels horizontally, as well as twice vertically).

Above: A precision nighttime hunting rig: the RS75 thermal on a MDT chassis, perched on a Two Vets Recon V2 tripod.

And if you’re running last year’s 340-pixel optic, prepare to FOMO on the fact that there’s a whopping 11.85 times more visual information coming out of the iRay RS75. A difference that’s hard to overstate.

The lens and sensor work together to gather many more photon waves worth of information than smaller systems, detecting target heat from as far as 3,600 yards away. That data is then converted to the familiar Predator-like thermomap, building a picture by assigning different-colored pixels to the varying levels of cold or hot.

Bigger sensor equals bigger box of crayons. The more levels of information make a clearer, more precise, and much larger video. But there’s a lot more to this story than the mere sensor spec.

Beginning up front where the picture quality starts, the RS75 has an unusually huge 75mm f/1.0 germanium lens. Germanium is a rare element that’s transparent to infrared radiation, so — unlike glass — it sees and sucks up that heat radiation instead of visible light waves.

While big lenses might usually be associated with high magnification, it’s used here for a different reason: as the thermal sensor gets larger, the width of the lens must be larger in order to keep the angle wide.

Above: This scaled representation compares what more pixels natively look like: The lower resolution sensors provide less data and smaller pictures. The RS75’s bigger 1280 pixel sensor brings in many times more information to build a larger — and less pixelated — view.

Having a big lens with a smaller sensor is like having an over-zoomed dayscope — you get a super-detailed closeup with a tight FOV. But put a bigger lens on a larger sensor like InfiRay Outdoor and you not only have a wide 2x native field-of-view, but also the available resolution to take advantage of higher levels of digital zoom.

Each time you zoom in on those pixels you’re losing picture quality. But since a 1280×1024 pixel count is so high to begin with (1,310,720 in total!), running up the digital magnification means an RS75 with a 2x digital zoom will have the same resolution as a native 640 sensor, or the resolution of a 384 sensor at 8x zoom. Hog hunters and hunters who need to track runners moving side-to-side will value the RS75’s FOV of 11.7ºx9.4º at the native 2x optical magnification. Higher magnification levels (4x, 8x, 16x, and the 32x maximum) use digital zoom in conjunction with the native 2x optical zoom to provide a usable increase for those who need to reach out farther.

Eyepiece and Batteries

If we haven’t lost you already with the camera-nerd math, let’s switch to the secret weapon that’s on the backside of this optic: the eyepiece. Simply put, it gives an impressive jump from old tech and a very immersive experience.

A traditional eyepiece in a thermal scope is just a simple, flat little display with a diopter to focus your eye to the screen. Whereas the lens system in the iRay RS75 is an orthoscopic (slightly curved and magnified) lens set that provides increased magnification of the display as well as lower distortion, allowing the 1280 sensor to truly pop from edge to edge.

Above: Some of the RS75’s menu screens as seen through the viewfinder. It’s easy to switch on Wi-Fi, change reticle type and colors, correct zero, see battery life, magnification levels, and many other options.

And it’s big. Most manufacturers don’t bother listing any specs other than the pixel count of their screens. They’re usually less than a ½ inch in size and put out 640×480 resolution, whereas iRay offers a huge 1.07-inch AMOLED screen with resolution of 2560×2560, about 6.5 megapixels. This makes for a forgiving eyebox with 60mm of relief.

You can literally stand back from the scope and still see the display without cramming your pupil into it. This is one of the exciting elements of this scope that we’d expect to easily trickle-down to lesser-priced units in the near future.

The refresh rate of the screen is 30 Hz, which isn’t the highest possible, but with so much data you have to blend battery life and processing power. When combined with the wide FOV and the resolution, the slower rate isn’t that noticeable.

Speaking of batteries, the unit comes with two batteries that can be recharged in the field or at home, and it can optionally run off aftermarket external USB-C power sources like you use to charge your phone. It’s certainly achievable to get a full night’s use out of the optic with the two included batteries.

Getting Physical

As far as physical size, it’s 12.28 inches long, 3 inches tall, with a 1.7-inch centerline of the eyepiece when it’s mounted to your rifle’s rail. That’s a similar length to a Leupold 3.6-18x44mm scope that we pulled off the Ruger SFAR .308 test rifle to mount the iRay.

Above: A 7.62 FN SCAR rifle kitted out with a Silencerco Omega suppressor and the RS75 thermal.

It includes a recoil-mitigating mount, which rates the system for recoil up to .300WM/7mm Mag. The whole setup is a bit chubby at 44 ounces, which isn’t entirely unexpected for all the tech crammed in it. Also, let’s face it: night rigs like this mostly get used on tripods, off truck hoods, and in deer blinds.

iRay RS75 Bonus Features

In addition to the bare guts of the unit, the bells and whistles are fun and useful as well. There’s a lot of emphasis on helping you share those high-definition thermal videos with the world. The RS75 records video and has newly improved audio capabilities to document your hunt, from picking up whispers of “going hot!” to capturing bullet impacts way downrange.

You can wirelessly stream photos and video to a smartphone app, broadcast your gunsight videos instantly to social media, or just store your content on 128GB of internal memory for in-scope or tablet review in the field.

Above: IRay’s recoil-reducing rail mount cuts down on shock transmitted to the optic by high impulse guns like the FN SCAR.

As a high-tech bonus, the RS75 ships with iRay’s ILR-1,000-yard laser rangefinder. It integrates with the unit, overlaying real-time distance data (accurate to +/- 1 yard) directly onto the thermal’s display so you’ll never have to guess how far away the target is or pull out a separate rangefinder.

Loose Rounds

It’s been about 10 years since this sort of big leap of technology happened in the thermal world, so iRay decided we were due for a new one. If you’re in the tax bracket that can afford this scope now, you’re going to be pleased. If you’re waiting for this tech to trickle down, you’re in luck too — but maybe next Christmas.

Written by Kel Whelan