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jeffbroadslover

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Infer red is not visible to the human eye but cameras pick it up. A little experiment you can do is to set your phone to camera mode and while watching the screen, aim your TV remote at it and press one of the buttons.

WARNING If you have infer-red security cameras, these can be detected by burglars aiming their mobile phones at the house. the cameras show up as bright white spots.

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3 hours ago, SwanR said:

*Hoping for totally non-technical explanation* :default_laugh:

Thanks - that's much clearer now! :default_dunce:

Night vision

Infrared is used in night vision equipment when there is insufficient visible light to see.[23] Night vision devices operate through a process involving the conversion of ambient light photons into electrons that are then amplified by a chemical and electrical process and then converted back into visible light.[23] Infrared light sources can be used to augment the available ambient light for conversion by night vision devices, increasing in-the-dark visibility without actually using a visible light source.[23]

The use of infrared light and night vision devices should not be confused with thermal imaging, which creates images based on differences in surface temperature by detecting infrared radiation (heat) that emanates from objects and their surrounding environment.[24]

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10 hours ago, DAVIDH said:

Seriously though, in the image I posted earlier, you can see the reflection of the light in with windows of boats moored before and after the main subject. Would an infra-red camera reflect as bright as that?

 

David that was exactly what I am struggling to understand. Because it did look as if the beam of light was moving with the camera as it moved round. Why wouldn't the whole picture look as bright as the central spot?

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21 minutes ago, chameleon said:

think it must be your end its ok on mine

Mmm. I usually use Microsoft Edge, so I've just tried Chrome instead and it works OK there. So you're right its my end.  Any tech savvy people know how to adjust settings in Edge, or will I have to use Chrome.

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To use a school physics explanation which technically isn’t true but works for illustrative purposes.

 

think of a rainbow all the light wavelengths we can see spread out by raindrops. ROYGBIV. 

The frequencies go much higher and lower than this central range.

The red end it doesn’t stop just cos we can’t see it, neither does it at the violet end , we can only see the bits in between. Digital Camera sensors can be set or designed to see whatever frequency you like. With less sophisticated ones just stick a filter on the front which removes everything but IR and fannies your Antie. 

Video cameras are good at this and are the reason they are banned in swimming pools as they see the IR radiation emitted by the body through the costume. Many people rightly arrested and prosecuted.

 

IR emissivity is a great topic to discuss as the current fascination with carbon dioxide is predicated on it. 

 

M

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The camera is like this the centre section, is the lens of the camera, each of the little glass dots around the lens all bar one, is an infra red LED (Light Emitting Diode). The other is a light sensative cell.

You can often see the LED's emmitting a faint red glow . On a Pan and Tilt Camera this is the reason the light follows the camera.

ir cam.jpg

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