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I have a Raspberry Pi IR camera with 2 attachable IR lamps. I am not sure if it is the same but it looks very similar to the Waveshare unit mentioned here frequently, eg in this question.

The goal of this little project is to watch wildlife, so I'm trying to turn off as many of the lights on the Pi and camera as possible.

I've disabled the main camera LED by adding disable_camera_led=1 to my /boot/config.txt, and that works fine.

However the IR lamps themselves also have a red light coming out of them, as if there's another red LED inside. The lamps are shining IR light which shouldn't be visible, so I am not sure what this red visible light is. A power or status indicator?

EDIT

Here's a photo of what I'm talking about. The red light seems to be coming directly from the lamp, as if the IR LED is also shining visible red light.

Red light from IR camera lamp

I haven't been able to find any mention of this visible red light, nor if it is possible to turn it off. Does anyone know?

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    To clarify, are your seeing the stray red light on the camera feed or with the naked eye? Have you tried masking the LEDs with tape or thick card to confirm that they are the source of the light? – Roger Jones Mar 12 '19 at 13:24
  • The red light comes directly from the lamp, as if the IR LED is also giving off visible red light. I've added a picture. – Don't Panic Mar 12 '19 at 23:00
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    that IR LED is a high-current 3V3 variant. Reduce the current with a resistor, and the visible red will fade into the invisible IR spectrum. don’t really know what the other people here are talking about; they don’t seem to answer your question. – user2497 Mar 13 '19 at 14:22
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Honestly I think that a dim red glow is a non-issue. Most cheap IR LEDs emit small amounts of red light, and intense near IR is also visible as a dark red glow. This doesn't prevent people from filming wildlife at night using these LEDs. Most animals have good smell too, so there's simply no way they won't notice your device. That doesn't mean they will be scared off by it. It's also worth noting that many cold-blooded animals like frogs and snakes can see IR just fine.

You can try to add an IR filter on top of your LEDs to further limit the visible light coming out of them, or use indirect illumination, but frankly I wouldn't bother.

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From what I've seen most IR LEDs for "night-vision" systems emit wavelengths of either 850nm or 940nm but from my understanding not all cameras are sensitive to the 940nm end so 850nm is the more common. This seems to be the case for the waveshare IR camera module (my Chinese is no good but there's a mention of "850 light" amongst the Google translted LED specs.).

Because IR light up to 1050nm can be perceived by some mammals as a dim red glow under the right conditions I think this is what you are seeing. Using 940nm LEDs might help (closer to 1050nm and so harder to see) but then the camera may need an upgrade as well and it's not a practical solution. You could try using a red filter on the LED to mask the visible part but check that the filter is not also going to block parts of the IR spectrum as well.

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