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Lies. :-) Somewhere in my HN comment history from a while back is a response to a person claiming that modern phone cameras can’t detect IR illumination and re

Lies. :-) Somewhere in my HN comment history from a while back is a response to a person claiming that modern phone cameras can’t detect IR illumination and remotes. I took a bunch of modern iPhones and Android phones, from colleagues in an IT dept, and demonstrated they can in fact see a bunch of different IR remotes and illuminators with the rear camera. I could find zero cameras that could not see the IR. I’m not sure where people got the notion they couldn’t.

JKCalhoun 2y ago
Guessing because they read that CCD's have IR filters on them.
runjake 2y ago
Update: here's the comment: https://news.ycombinator.com/item?id=40513967 https://news.ycombinator.com/item?id=40513967
pwg 2y ago
The ultimate answer is "it depends". And upon what it depends is the particular IR wavelength the camera emits to "illuminate" a scene in IR for night photography. My cell phone's back camera will show IR light from IR remote controls (I've used it for just that to verify that a remote is transmitting). But I also have an outdoor IP camera with IR illumination in my back yard. The same cell phone camera sees zero IR emitted from the outdoor IP camera (even though it quite well lights up a fairly broad area of the yard at night). So for my phone, if a 'spy cam' were using the IR wavelength the IP camera uses, I would never know it was present by using the phone camera. If it used something closer to the wavelength used by IR remotes, yes, then the 'spy cam' would light up via the phone camera.
lightedman 2y ago
"I’m not sure where people got the notion they couldn’t." I make IR devices. My phone is the only one in the warehouse that can pick up their emissions - everyone else's cameras have IR filters with what appears to be a sharp ~750nm cutoff. I'm the only one that will pick up 800-1064nm with my cheap Samsung, and so I'm the only one doing the testing on those diode assemblies.
Ballas 2y ago
Ok, I'll admit that I have not tested that many phones, but all the phones I had in the last ~8 years would not detect my remotes unless I used the front camera. That could very well be because all the remotes I tested operate on 940nm instead of 850nm (the two common options), and the IR filter in my devices are so that it would cut the one but not the other. Or that they just have a much lower power level. Either way, most modern phones that double as cameras will have an IR cut filter of some sort, otherwise some photos appear weird - like the red glow from a fire will appear purplish-white.

JKCalhoun 2y ago

Guessing because they read that CCD's have IR filters on them.

runjake 2y ago

Update: here's the comment: https://news.ycombinator.com/item?id=40513967 https://news.ycombinator.com/item?id=40513967

pwg 2y ago

The ultimate answer is "it depends". And upon what it depends is the particular IR wavelength the camera emits to "illuminate" a scene in IR for night photography. My cell phone's back camera will show IR light from IR remote controls (I've used it for just that to verify that a remote is transmitting). But I also have an outdoor IP camera with IR illumination in my back yard. The same cell phone camera sees zero IR emitted from the outdoor IP camera (even though it quite well lights up a fairly broad area of the yard at night). So for my phone, if a 'spy cam' were using the IR wavelength the IP camera uses, I would never know it was present by using the phone camera. If it used something closer to the wavelength used by IR remotes, yes, then the 'spy cam' would light up via the phone camera.

lightedman 2y ago

"I’m not sure where people got the notion they couldn’t." I make IR devices. My phone is the only one in the warehouse that can pick up their emissions - everyone else's cameras have IR filters with what appears to be a sharp ~750nm cutoff. I'm the only one that will pick up 800-1064nm with my cheap Samsung, and so I'm the only one doing the testing on those diode assemblies.

Ballas 2y ago

Ok, I'll admit that I have not tested that many phones, but all the phones I had in the last ~8 years would not detect my remotes unless I used the front camera. That could very well be because all the remotes I tested operate on 940nm instead of 850nm (the two common options), and the IR filter in my devices are so that it would cut the one but not the other. Or that they just have a much lower power level. Either way, most modern phones that double as cameras will have an IR cut filter of some sort, otherwise some photos appear weird - like the red glow from a fire will appear purplish-white.