I saw a random video clip yesterday where they clipped a red transparent card over the phone camera; turning on the camera flash, and scanning the room using the camera's video camera mode. The light from the phone reflected in small spy cam lenses, showing up as tiny red dots on the screen.

Can you link a source to this? It sounds incredibly cool.

Or just turn off all the lights in the room and use your iPhone camera in live mode - hidden cameras (and their IR emitters) will light up like a Christmas light.

That's only if the hidden camera is actually using an infrared led / led array. Also you might have better luck using the front camera because it is more sensitive to IR.

If it isn't using infrared leds, you can at least get undressed in the dark with little worry.

This may vary based on the wavelength emissions from the IR LED's:

https://ellipsesecurity.com/2018/05/850nm-vs-940nm-ir-illumi...

Is this an iphone specific thing ? Have you tested it.

It's not actually. Most digital cameras pick up infrared light, especially cheaper ones. Maybe not professional cameras, which might have an IR filter for better color accuracy. The filters are not cheap and IR doesn't affect the image quality all that much.

Try it out; point your TV remote at your smartphone camera and push the buttons. You might be able to barely see the light with your eye in dark conditions, but the blinking pattern should be bright and easy to see through your phone.

I've tried this; you can definitely pick up the IR light with the front camera of your phone. Rear camera has an IR filter in modern cameras or something.

Can confirm. Just saw red light on my TV remote w/ my LG G5. Pretty interesting!

Every camera I've tried this with displays the IR as a pinkish purple color. You can sometimes see that same color in photos of things like sunlight reflecting off of chrome, or refracting through windows.

Depends on whether your camera is equipped with an infrared filter. Some older camcorders actually have low-light modes based on infrared or near infrared light. You should be able to use those as well.

No, it's not iPhone specific.

You can always test yours with any IR remote control - just point it at the camera, press any button and you should see the LED blinking.

You can test it with a classic remote control where you can see the beam when you press a button if you point it directly at the camera lens.

I only have an iPhone 5, it works with the front camera. The back camera has an IR Filter.

> You can get a used FLIR for around $100.

The cheapest ones I have found are around $500. What FLIR device are you talking about?

You can get the one for smartphones for $200 brand new. https://www.flir.com/products/flir-one-gen-3/

You can also use a non linear junction detector

https://en.wikipedia.org/wiki/Nonlinear_junction_detector

They are electronically very simple (they are the boxes with wands and earphones you always see in espionage movies)

Quoting from the wiki article:

> As a countermeasure against an NLJD, professional covert listening devices (bugs) of the Central Intelligence Agency were equipped from 1968 onwards with a so-called isolator. An isolator is a 3-port circulator of which the return ports is terminated with a resistor. Any energy injected into the bug by an NLJD, will be absorbed by the resistor, resulting in no (or very little) reflected energy. An example of such a bug is the CIA's SRT-107.

Do modern concealed spy cameras have this kind of tech? Is there anyway to counter such a counter-measure?

It would require it being built into the IC itself, and no ICs except ones intelligence agencies have access to are going to offer this feature, because it has no other real purpose than evading NLJDs

But they are about $10k, and sadly one of the few things where I don't think there are any working DIY ones.

sidebar:

Why did "forward looking" get glued onto that acronym? Why not just IR camera or detector? Did the military have less popular rear or side looking infrared devices? maybe "FLIR" was just fun to say? On a rocket powered missile rear-looking infrared seems pretty useless.

Yes, early infrared imaging systems were "push broom"[1] scanners facing perpendicular to the direction of travel. Forward-looking sensors required some additional tech to be developed: https://en.wikipedia.org/wiki/Forward-looking_infrared#Origi...

FLIR is arguably a misnomer when applied to handheld devices, though.

[1] https://en.wikipedia.org/wiki/Push_broom_scanner

this doesn't help when it's hidden in the workings of another electronic device which creates heat.

I think the general assumption here is that a hidden camera would be likely to use active IR illumination.

ah; I misunderstood. thanks.

Also remember, thermal heat would be present and difficult to isolate from hidden cameras located in seemingly harmless electronics.

How does it detect the curvature?

I think it probably measures the curvature and if the curvature exceeds the normal parameters of non-lens objects then the device has curvature and can be detected.