What's better than having a thermal camera capable of finding the freshest cinnamon buns — among other prey? The FLIR ONE accessory gave iPhones Predator-like thermal vision which turned out to be as awesome as it sounds, and now a company called Seek Thermal is promising the same with an iOS and Android-friendly smartphone accessory that makes a few compromises for a cheaper price tag.

What Is It?

Thermal cameras have been around for decades now, and over time they've gone from huge units strapped to the front of police helicopters to handheld devices that can be carried into dark buildings. But Seek's Thermal is the first infrared camera that's small enough to be attached to the bottom of your smartphone. It relys on your device's processor, battery, generously-sized touchscreen, and a free accompanying app. It's quite possibly the smallest thermal camera currently on the market, and that's awesome.

Who's It For?

With a price tag of $200, the Seek Thermal is $150 cheaper than the FLIR ONE iPhone accessory, so first and foremost it's for anyone who's ever wanted a thermal camera, but doesn't want to spend a fortune. Most people interested in the Seek will probably never use it as anything other than a toy or a fun party trick, but it does have practical applications: You can use it to do anything from spotting intruders, to saving money on your heating bills by hunting down cracks in your home's insulation.

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And let's not forget that the FLIR is only accessible with the iPhone 5 and iPhone 5S at this point. The Seek can be used with iPads, the new iPhone 6 or iPhone 6 Plus, and many of the millions of Android smartphones in the world—as long as they support the USB on the Go (USB OTG) standard. (Sorry, Nexus 4 users.)

Design

Because the Seek relies on a smartphone for so much of its functionality, the rest of the hardware can be incredibly small. It's barely an inch-and-a-half long, and I found I could easily slip it into a pocket when it wasn't in use. Instead of cheap plastic, the Thermal's housing is made from magnesium so it feels incredibly durable. And even though it's tiny, it doesn't feel delicate, so you'll never have to baby it. You'd have to be pretty determined to damage it.

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The Thermal's camera lens is recessed about a quarter-inch into a sort of carved metal lens hood that helps to protect it from scratches. Seek claims the lens provides a 36-degree field-of-view which isn't as wide as you'd get from something like a GoPro, or even most smartphone cameras. But it never feels particularly narrow or cramped while you're using it, and the narrower field-of-view helps maximize the sensitivity of the camera's limited resolution.

Inside the housing you'll find the Thermal's infrared sensor, with a resolution of 206 x 156, for a grand total of 32,136 thermal-sensing pixels. That's considerably smaller than the sensor you'll find in the camera of even the cheapest of smartphones, but it's actually far more than the Lepton sensor used in the FLIR ONE with a resolution of just 80 x 60 pixels, or 4,800 in total. So in terms of resolution, Seek claims a win.

The back of the Thermal is just as plain as the front (save for a silk-screened logo) and is devoid of any buttons, toggles, or blinking LEDs. Settings, modes, and calibration are all handled by the accompanying Seek Thermal app, which is what allows the actual hardware to be as plain and simple as possible.

In fact, the only physical feature that distinguishes the Android version of the Thermal from the iOS model is the connector you'll find on top. For iPhone and iPad users it comes with a Lightning port, while Android users will find a microUSB port.

And for those who refuse to leave the house without their pristine devices protected in cases, sleeves, or durable housings, the Thermal comes with a surprisingly sturdy case of its own—complete with a thick rubber lining with a cut-out for the camera to cozy into, and a lid that snaps shut tight to keep dust and moisture out.

Using It

Given how simple Seek's hardware is, all of the actual functionality is handled by an app. And surprisingly, despite a price tag that's $150 cheaper than the FLIR, the free Seek Thermal app manages to pack in a bit more functionality.

When the app is launched you immediately get the live Predator-like thermal vision you probably bought this for, with the ability to snap photos or shoot videos in that mode. Given the limited size of the Seek's IR sensor, its quality is very limited compared to the images your smartphone's camera can snap, resulting in photos with a resolution of just 832 × 468 pixels after interpolation. But unlike with the FLIR, your thermal images aren't automatically and permanently watermarked with the company's logo—which is nice.

If you're not interested in taking pictures, the app includes other modes that provide additional useful functionality. You can activate a simple text overlay that shows the exact detected temperature of whatever's in the center of the frame.

Or you can have the app automatically track and display the hottest and coldest areas of what's in frame, updated in near real-time. Unfortunately the sensor doesn't seem to update at a full 30 frames per second like full-motion video does, but the stuttered updates are frequent enough so that the app doesn't feel sluggish to use.

There's even a particularly useful mode that lets you set a specific threshold, highlighting only areas in the image that are above a given temperature. This makes it particularly useful for hunting down drafts in your home, letting you easily ignore everything but areas that are being registered as colder than the rest of a room.

One point of frustration with using the app, though, is that its camera functionality is disabled when using these other modes. Snapping thermal image photos with the actual temperature info overlaid could certainly be useful to some users, but unfortunately the only way to do so is to take a screenshot, assuming your device allows it.

Thanks to the larger sensor used in the Seek Thermal's camera, it's able to generate more detailed thermal images than the FLIR can. However, while using the Thermal it soon becomes clear why FLIR is the more expensive option.

When using the Thermal camera on subjects with a well-defined and distinct heat signature, it's pretty easy to figure out exactly what you're looking at.

It's sensitive enough to distinguish areas of bare skin on a person versus areas where they're wearing clothing, and looking at images like this it's fairly easy to interpret this as a room full of people.

But when the differences in temperature aren't as varied, distinguishing what you're looking at when the using the Seek becomes a little more difficult. Here we see crowds of people in a warm shopping mall, and while they're still mostly defined, it's hard to pick out specific details.

At its worst, the Thermal produces images like this. Can you tell what was photographed here? The same photo taken with the FLIR (below) is a lot easier to decipher.

Believe it or not, those are both photos of the same display case full of sushi. The Seek's image still shows variations in temperature, but figuring out exactly what you're looking at is almost impossible. (In fact, there were a couple of photos I took for this review that I still can't quite figure out.)

In the thermal images taken with the FLIR you can actually spot the different types of Maki in the various plastic food containers. But why the huge discrepancy? Because the FLIR is actually taking multiple images at once.

The compact Seek Thermal uses a standalone thermal sensor to produce its images, whereas the FLIR iPhone case uses a pair of side-by-side cameras and software tricks to produce hybrid shots. One generate outlines of objects in the frame, the other takes temperature data,and the app merges them together in real-time. It makes it easy for someone who's never used a thermal camera before to tell what's going on.

To its credit, the Seek Thermal app does try to mimic the FLIR ONE's neat hybrid image functionality with an additional mode that puts the thermal image it generates alongside the image from your smartphone's built-in camera, allowing you to swipe back and forth between the two. But because they have different field-of-views and are so far apart, the images don't line up, particularly when shooting objects up close.

How well this mode will work will vary from smartphone to smartphone since the position of their camera lenses will vary, but for the most part it doesn't quite match what the FLIR is capable of.

Like

Even if you have no practical use for a thermal camera, the Seek Thermal makes for a fun accessory that adds some truly unique functionality to your smartphone—there's no denying that. Unlike the FLIR which requires you to put your iPhone in a case, the Seek can easily hang off most iOS and Android devices or be easily stashed in your pocket.

But it wasn't just the hardware's small and durable form factor I liked. While using the Seek Thermal you can hear it making frequent quiet clicking sounds, almost like the sound of the iris stepping down on a camera. It turns out that sound is actually the Seek Thermal's camera automatically and continually recalibrating itself while you use it. On the FLIR you have to pull a manual lever every so often as you find the thermal images degrading, which is a bit of a pain.

The FLIR comes with its own built-in rechargeable battery so as not to completely drain your smartphone while you're using it. But while the Seek Thermal camera leeches power from your smartphone, I actually preferred not having yet another device to remember to charge. The battery drain while using the Seek Thermal wasn't significant enough to worry about, anyhow.

Overall, Seek's app feels a little snappier than the FLIR, which felt like it could use a bit more TLC before it officially made its way to the consumer.

No Like

Even though the thermal sensor on the Seek Thermal is packed with more pixels than the sensor in the FLIR, it's clear why FLIR designed its hardware with the additional side-by-side cameras. It adds to the size and cost of the FLIR, but it also increases the functionality and usability producing thermal images that are always easy for anyone to distinguish.

That's unfortunately not always the case with the images produced by the Seek Thermal. When using it as a tool to provide real-time thermal images of what you happen to be looking at in the moment, it's straightforward enough. "Is this coffee to hot to sip? Yes it is." But after the fact, you might have a difficult time remembering what's going on in a photo you snapped.

Should You Buy It?

Yes, if you're willing to make some compromises. On paper the Seek Thermal sounds like an improved version of the FLIR in every way. The hardware is smaller, its thermal sensor has more resolution, and it's $150 cheaper than the competition. But it turns out what makes the FLIR bulkier and more expensive also vastly increases its usability and user friendliness.

That's not to say the Seek Thermal doesn't work—far from it. It certainly generates accurate thermal images with enough extra functionality in the accompanying app to justify it as more than just a fun accessory for your smartphone. It's just that the FLIR approach results in images that are more than just blobs of color.

So if you're happy to sacrifice a small bit of usability to save $150, you won't be disappointed by the Seek Thermal's capabilities. Or if you happen to use a smartphone that's not an iPhone 5 or iPhone 5S, this is currently your only option when it comes to a compact thermal camera. But if you're hoping to be the hit of your next party, you might be better off spending the extra money for the FLIR ONE — so your guests aren't left scratching their heads.