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.
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.