A thermal camera shows you what your eyes can't — hot components, missing insulation, water leaks, electrical faults. The technology has gotten dramatically cheaper in the last 5 years. Resolution and thermal sensitivity are the specs that matter — megapixel counts mean nothing here.
Thermal resolution is measured in pixels — not megapixels like visible cameras. 80×60 (4800 pixels): Entry level. Spot temperature readings, basic fault finding. 160×120 (19200 pixels): Good detail for PCB inspection, building diagnostics. Sweet spot for value. 320×240 (76800 pixels): Professional detail. Clear component identification. 640×480: Research grade. Most sensors are uncooled microbolometers — cooled sensors (InSb, MCT) exist for scientific/gas detection work at 10x the price.
Noise Equivalent Temperature Difference — the smallest temperature difference the camera can detect. 100mK: Budget. 50mK: Good. Fine for most work. 30mK or less: Excellent. Subtle temperature gradients visible. Matters for PCB work where you're looking for 1-2°C differences, not 50°C hot spots.
-20°C to 150°C: Building diagnostics, PCB work. Most common. -20°C to 550°C or 650°C: Electrical panels, industrial equipment, brake rotors. 1000°C+: Furnaces, high-temp industrial. Accuracy is typically ±2°C or ±2% (whichever is larger). A camera that reads to 650°C but with ±10% isn't useful.
FLIR's MSX (Multi-Spectral Dynamic Imaging) overlays visible-edge detail onto the thermal image — you can read labels and see component outlines. Extremely useful for PCB work where pure thermal looks like blobs. Other brands have similar tech under different names. A pure thermal image without visible overlay is much harder to interpret.
Phone attachment (FLIR One, Seek, InfiRay): $150-400. Convenient, always with you. Lower resolution (80×60 to 160×120). Battery powered (phone drains fast). Good for quick checks. Standalone: $400-5000+. Better resolution, better sensitivity, dedicated battery, rugged. For serious/professional use.
Entry ($150-400 used): FLIR One Pro, Seek Compact Pro, InfiRay P2. Phone-attached, 160×120-ish.
Mid-Range ($500-1500 used): FLIR E5-XT/E6-XT (hackable), Hti HT-301, Uni-T UTi260B. Standalone, 160×120 to 320×240.
Professional ($2000+): FLIR E8/E53+, Testo 890. High res, high sensitivity, radiometric data.
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