Many cameras designed for everyday use can detect all wavelengths of visible light, but also a bit of the infrared spectrum. This can be seen by looking at the infrared light emitters on a TV controller with the naked eye (invisible) and then with a camera (visible). However, I am aware that most objects, including the human body, constantly glow in the infrared spectrum. Despite the camera being able to detect infrared light, I have never been able to tell the difference between hotter and colder objects with a regular camera. I also have never noticed a difference visually between objects as seen with the naked eye versus through the camera. Is the infrared glow that everyday objects have too weak? Do the cameras themselves adjust for this everyday glow? And would temperature be "visible" through a regular camera because of this slight detection in the infrared spectrum if an object was warm enough?
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$\begingroup$ The intensity of the infrared light emitted by a remote is much higher than that of a human body. $\endgroup$– TobiCommented Dec 24, 2016 at 2:17
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1 Answer
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At room temperature, the blackbody spectrum has its maximum at a wavelength around 10 micrometer, in the far IR. Photon energy is much smaller than the bandgap of semiconductor cameras.
Remote controls work with near IR light-emitting diodes, around $\lambda \approx 1 \mu$m, with photon energy large enough to excite electrons in silicon.
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$\begingroup$ For what it's worth, you can see this effect clearly on objects hot enough to also glow in the visible spectrum - you may have noticed the red glow seen with the naked eye becomes closer to pink or purple with such a camera. $\endgroup$ Commented Oct 15 at 11:50