Going Thermal

FLIR Systems

Mosquitoes have something you don’t. Okay, they have a lot of things you don’t. But one of them, apart from that whole blood-drinking habit, is heat vision. Specifically, females use infrared-like sensors to home in on your hot spots—areas where an accessible meal is likely to be found.

Fortunately, technology has caught up with them. The FLIR One is an infrared (IR) camera that fits onto your iPhone 5/5s and adds heat vision. It can see in the dark by detecting the heat radiation emitted by objects. Equipped with dual cameras, the FLIR One takes both IR and visible light images, combining the two to form the final image. The IR camera is much lower in resolution (80 x 60 pixels) than the visible-light one (640 x 480 pixels), so this approach produces an image that looks sharper than the pure IR image. The visible-light image is processed to show only the edges of objects, then the false-color IR image is overlaid on this (the iPhone camera is not used). This false-color IR overlay has a number of palettes available, including ones that highlight the hottest and coldest parts of the image, a rainbow effect, and a palette called Iron that has the more classic, Predator-vision style look.

The downside of this two-camera approach is that, although they are located side by side, they see slightly different images, and the two aren’t quite aligned when shooting objects that are close to the camera. This effect (called parallax) was noticeable on objects a couple feet from the camera, and very noticeable with closer ones. An app called CloseUp is available from FLIR that tries to compensate for this by allowing you to manually shift one of the images, but it doesn’t help much.

All this means the camera won’t work for examining small objects, such as trying to find a hot component on a circuit board (FLIR recommends that the subject is at least 3 feet away). It isn’t an issue with larger components, though, and I could easily see things like which circuits in my electrical breaker box were active by their slightly higher temperature.

Two IR images of my electrical breaker box, with the electric tumble dryer off (left) and on (right). The fuses are hotter in the right image because of the current being drawn by the dryer. Richard Baguley

You can also capture videos with the FLIR, but don’t expect HD quality. You’re stuck with that 640 x 480 pixel resolution, with a frame rate of about 9 frames a second. There are also a lot of glitches in the video if there is a lot of movement (see below), so it is best used when holding the camera still.

IR Panoramas are also possible. After downloading the appropriate app, you use the same press-the-button-and-pan-the-phone approach as the Apple Photo app. It’s worth noting, however, that this process is much slower—the image takes a considerable time to process when the panorama has been taken, and it doesn’t do as good a job of blending the images together either.

It doesn’t take much use before you find that the case’s IR sensor also requires a good deal of recalibration (FLIR calls this tuning), which involves pulling down the power switch on the back and holding the switch down until the device bleeps. This has to be done every time the camera is turned on, and every few minutes when in use.

The FLIR One adds a lot of bulk to the phone, but not a lot of weight: The IR camera portion adds 3 ounces, for a combined weight of 7.6 ounces. When you aren’t using the IR camera, most of it can be removed from the phone, leaving behind a simple bumper case section on the iPhone body. Which means your existing iPhone case, if you have one, is heading for the trash. You can’t use the FLIR One without this bumper case part. Taking the camera back off the phone and bumper case is fairly easy, though—a simple tug of the phone and it comes loose.

That’s good, as you’ll be doing it a lot. The iPhone and the FLIR One have to be charged separately, and you can’t charge the iPhone while the camera back is in place. The camera back charges from an included micro USB power adapter and cable, so you’ll need to take two chargers and regularly disconnect and reconnect the FLIR One for each charging session. FLIR claims a 2 to 3 hour battery life, which seems about right. Only the most ardent user is likely to run the FLIR One battery down before the phone itself runs out. On the upside, this rather awkward arrangement means that the FLIR One doesn’t drain your iPhone battery when in use; It is completely self-powered.

The FLIR One can also double as a spot temperature meter, giving you the temperature of a spot in the middle of the screen, accurate to 1 decimal place. This does require more frequent tuning, though (every 2 to 3 minutes in this mode). The spot temperature mode can also only measure between 32 and 212 Fahrenheit, the freezing and boiling points of water. Try and measure anything above or below that and you get a reading of > 32 F or < 212 Fahrenheit, which isn’t much use for testing a freezer or a kettle.

The FLIR One is certainly an interesting product, but I found myself constantly saying “if only” when writing this review. If only the charger could recharge both the device and the phone at once, it would be easier to keep both charged. If only the temperature range of the sensor was a little wider, I could use the spot sensor to check how far below freezing the food in my freezer is. If only it could be used to take IR photos of small objects. If only the final images and videos didn’t have a FLIR logo in the corner all the time…

Of course, the FLIR One is the first product of its type, so some limitations are expected. And I don’t doubt that FLIR and others are already working on the next generation of this device that may get around these issues. With this first pass, the company has built an interesting and occasionally fun device. Hopefully it can add some utility to the next version.