I thought I would have a quick play with my new-to-me FLIR SC660 top-end (but discontinued) 640x480 camera vs my much cheaper Therm-App Pro, also 640x480.
First, I want to make it quite clear that this is a thoroughly unscientific test. The images were all made hand-held, meaning that although subjects are the same they aren't taken from the same angle or even distance. The FLIR has a 40mm lens of as-yet-unknown aperture; all the Therm-App Pro images were taken using the standard 19mm f/1.1 lens.
The big, big difference between the cameras is that the FLIR is fully radiometric and the Therm-App Pro is not. (In fairness, it doesn’t pretend to be). The FLIR is designed for making scientific measurements, whereas the Therm-App Pro is really only about making pretty pictures. So although the resolution and NETD (sensitivity) figures for the two devices are similar, that’s really where the similarity ends.
I should say that I'm very familiar with using the Therm-App series of cameras but have only had the FLIR for a couple of days. I haven't used any 'tricks' to make either camera look better or worse; as far as I can tell it's a reasonably fair comparison, subject to the notes herein. The Therm-App Pro was 'driven' by the non-stock app, ThermViewer, which generally produces slightly better images than the stock app and includes a calibration routine rather like a manual version of the NUC shutter in the FLIR. I did use this option, which results in marginally better images than the stock app.
ThermViewer uses real-time superresolution to increase the native 640x480 images to 1280x960. Therefore I have re-sized all of the Therm-App images by 50% to 640x480. I will post the large versions separately.
This first image isn't actually a comparison: it's what I saw when I put the Therm-App up close against the FLIR lens. The speckling is, I presume, dust within the optical system. There are splodges on many of the FLIR images that could well be caused by these bit of dust; when I find out how to remove the lens I'll give it a whoosh with the air duster.