Thermal imaging cameras are fundamentally low-resolution. The thermal core they use can’t pick up a tiny fraction of the number of pixels you get on even a cheap conventional camera sensor, and even models with QVGA (320-by-240) resolution can cost thousands of dollars and are limited to specific professional applications. That’s why Flir, one of the leading companies in thermal imaging, has stuck to an 80-by-60 resolution for its consumer-level Flir One camera phone accessories for years. That’s also what makes the $ 399.99 Flir One Pro stand out. It has a thermal resolution of 160 by 120, quadrupling the number of pixels it can capture. Combined with the ability to measure higher temperatures than the third-generation Flir One or the Flir One Pro LT, the Flir One Pro is by far the most powerful model yet, and our Editors’ Choice.
The Flir One Pro looks more rugged than the slightly rounded, metallic silver-pink Flir One, with a slightly chunky black body and sharper angles that invoke a piece of professional imaging equipment. Despite the blockier look, it’s nearly the same width and height (2.7 by 1.4 inches) as the Flir One, and only a tenth of an inch deeper at 0.6 inches. Unless you have a nearly extinct four-inch-screen phone, the Flir One Pro will likely be narrower than whatever you connect it to.
Whether the version you pick is USB-C, micro USB, or Lightning, the connector sits in the middle of the top panel of the camera. It’s flush with the panel by default, but a mechanical wheel below the connector lets you extend it up to an extra 0.3 inches, so it can work with nearly any phone case. I had no problem connecting the Flir One Pro to a Google Pixel 3 XL even with the phone in a rugged case.
The bottom edge of the Pro holds a power button and a USB-C port for charging with the included USB A-to-C cable (a wall adapter isn’t included). The camera uses its own internal battery rather than running off of your phone, so it has to stay charged to work. Flir says the camera can reach a full charge in 40 minutes and can last up to an hour of thermal imaging. Besides the charging cable, the Flir One Pro comes with a hard, zip-up case for storage.
The front (or back, depending on how you connect it to your phone) panel holds the Flir One Pro’s two cameras, aligned with one on top of the other. One camera is the thermal core, a 160-by-120-resolution sensor that measures heat through infrared emission. This is the heart of the Pro, and one of the most expensive components of the device. The other camera is a conventional 1,440-by-1,080 visual camera, designed to work in tandem with the thermal core to produce photos and videos of much higher resolution than 160 by 120, through Flir’s Multi-Spectral Dynamic Imaging (MSX) feature.
The Flir One Pro requires the free Flir One app for Android and iOS to work. Once installed, turning the Pro on and plugging it into your phone lets you start looking at thermal readings. The app’s main screen is a camera view that shows a live feed from the Flir One Pro’s cameras in MSX mode.
While the Flir One Pro’s thermal core is a much higher resolution than the 80-by-60 cores in the Flir One and Flir One Pro LT, it’s still only 160 by 120, and so will only show broad blotches and vague shapes on its own. That’s why Flir uses its MSX image processing to combine the thermal image with the larger and more detailed view of the visual camera. MSX analyzes the contours of objects the visual camera sees, and displays them as transparent lines over the thermal image to help you identify what you’re looking at.
The MSX view can be switched to just thermal or just visual views with a tap on the menu that pops up from the lower right corner of the screen. This menu also lets you choose from nine different color palettes including the default orange-and-purple Iron palette. You can also look at the thermal readings with five other color gamuts, grayscale, and grayscale with the coldest parts of the frame highlighted as blue or the hottest parts of the frame highlighted as red.
If you aren’t sure what the colors mean, the IR Scale option in the pop-up menu shows the full color gamut of your chosen palette, with maximum and minimum detected temperatures labeled. You can also move those extremes by dragging them up and down the scale to adjust what colors are displayed in what temperature ranges. The Pro automatically adjusts the gamut based on the temperatures it currently detects in view, but you can also lock the range to whatever it’s looking at with another tap.
For precise temperature measurements, the crosshair button at the top of the screen offers three different temperature meters. You can find out the measured temperature based on a single spot, a larger circle, or a rectangular space. They appear in the center of the frame, but you can drag them around with your finger to check the temperature of anything in the frame. This number won’t be quite as precise as a thermometer, because distance and texture can affect how a thermal imager measures heat, but it will offer a fairly accurate approximation.
You can capture still photos, videos, and time-lapse recordings through the Flir app, all saved at 1,440-by-1,080 resolution. Videos are saved as MP4 or MOV files (depending on Android or iOS versions of the device). The app retains all the thermal imaging data, letting you toggle between MSX, thermal, and visual views; change palettes; adjust temperature ranges for the chosen palette; and meter specific temperatures. Effectively, whatever you can do to adjust the picture while you’re taking it, you can also do with the picture after it’s taken. However you adjust the picture, you can then save and share a standard JPEG file through any app or service on your phone.
Higher Resolution and Hotter Temperatures
The Flir One Pro’s 160-by-120 thermal resolution is one of its biggest advantages, with four times the number of thermal imaging pixels as the 80-by-60 Flir One and Flir One Pro LT. The photos and videos it captures are the same resolutions due to the identical visual camera and MSX processing, but they can show much more thermal detail thanks to the extra pixels. The contours and boundaries of hot and cold spots are far more distinct through the Flir One Pro, producing a massive jump in imaging quality and usability from the other versions. Objects that looked like vague splotches through the Flir One are much more easily discernible through the Flir One Pro.
Left to right: Flir One, Flir One Pro
Besides the higher resolution, the Flir One Pro’s thermal core can also measure objects three times hotter than the Flir One and Flir One Pro LT. By default, it measures a temperature range of -4 to 248 degrees Fahrenheit, like the other Flir One devices. You can switch into the higher temperature mode in the app to move the minimum temperature up to freezing (32 degrees Fahrenheit) and bump the maximum to 752 degrees.
Unless you’re a firefighter, blacksmith, or hold another highly specialized role that involves dealing with high temperatures, you probably won’t find much need to use the Flir One Pro’s high-temperature mode. The 248-degree maximum of the standard mode is enough to analyze heating vents, hot water pipes, and computer power supplies. For most users, whether handyperson or ghost hunter, you’re much more likely to find temperatures that dip a few degrees below freezing than over 500 degrees above boiling.
The Most Thermal Power
The One Pro is Flir’s most powerful consumer-level, phone-based thermal imager. Its jump in thermal resolution alone justifies its $ 400 price compared with the $ 200 Flir One and the $ 300 Flir One Pro LT, and its ability to measure much higher temperatures is a handy extra for some, and essential for others. The wealth of information you can get with every shot, including multiple metering options for checking temperatures anywhere on the frame, is a significant boon over the center-spot-only meter of the Flir One. As such, it earns our Editors’ Choice as the best consumer-level thermal camera available.
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