The Flir One Gen 3 is the largest thermal camera I’ve reviewed; it’s about 2.6 inches wide and 1.3 inches tall, which is a great fit for that space, including a built-in battery and two cameras. It’s also the most complicated camera I’ve reviewed. This large camera body has rounded edges and two rubber grips on the side and a USB-C connector at the top that matches a USB-C port (iOS version has a Lightning connector), which is what only keep it in place.
Flir saves images at a remarkable 1,440 x 1,080 pixel resolution, but that’s a scam. Well, maybe cheat too strong a word, but some tricks are going on here. The infrared sensor only takes 80 x 60 pixel images. To create a higher resolution image, the device smooths and scales the lo-res thermal image and combines it with a much higher resolution visible light image from the second camera is located right next to the infrared camera. Well, this device adds two cameras to the many cameras your phone already has.
It can be a bit sneaky, but it works. Visible light cameras add a spooky edge-painting effect to an image that can be very helpful when trying to identify a heat source—such as which side of a window is leaking warm air or which component on the board is overheating—because it provides a visual map.
The downside of this complexity is that it requires more energy. To get around this, Flir includes a spare battery in the camera that you have to charge via the USB-C port on the bottom of the device. If you do not charge, the camera does not work. You must also turn on the camera by pressing a button on the bottom of the device once it is plugged in, then wait about 20 seconds for the Flir One app (available for iOS and Android) to detect the camera. The images you get are great, but it all feels too complicated compared to other cameras and this is one more device that needs to be charged.
The problem with this (and other thermal cameras) is that they plug into the phone’s charging port, which requires a snug fit to work. If you have a case on your phone, you may not be able to fully plug in the device. However, the adjustable plug here is a nice solution; rotate the wheel below the connector so that the wheel moves up and down, creating an adjustable length to accommodate different thickness phone cases. To use the Seek Thermal and Prime Perfect cameras, I had to remove the case from the phone or use an extension cable because the case blocked the plug from fully entering the phone’s socket. However, the Flir One Gen 3 worked with a rather thick Samsung case on my Fold 4.