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Night vision cams

Discussion in 'Alarms, CCTV & Telephones' started by festive, 16 Sep 2015.

  1. festive

    festive

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    Ok i have a door entry system i have installed. HAs a few puny little leds on the entry keypad apparently utilising 940nm leds is that different to IR led? Im guessing the camera has to have a specific sensitivity to x frequency of light?
    I had a quick go at shining my IR spotlight over the area of my entry camera FOV and didn't seem to illuminate hence im guessing i need a 940nm version?

    thoughts appreciated.
     
  2. sparkymarka

    sparkymarka

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    The 850 nm wavelength is standard for most applications, including CCTV. The light source does produce a faint red glow at direct exposure, but otherwise is not visible to the naked eye. Most of the true Day/Night cameras with physically removable IR cut filter have great sensitivity to 850nm wavelength, that’s why they are so widely used for IR illumination.

    The main advantage of the 940nm wavelength is its complete invisibility. The light source doesn’t emit any glow. This is imperative for law enforcement and military, as well as for traffic and railroad applications where red light can be interpreted as a signal. However, only a handful of cameras are sensitive to 940nm wavelength. The illumination range is 30-40% shorter
     
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  4. EightyTwo

    EightyTwo

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  5. bernardgreen

    bernardgreen

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    If the camera is to be used for both daylight and IR night vision it will need a lens that has the same focal length for IR as it does for visible light. Or it will need to have variable ( automatic ) focusing. Otherwise while the image will lose fine detail with things like the image of a number plate being blurred and thus unreadable. It can be cheaper to use two cameras, one set up for day light and the other set up for IR

    If you need recognisable images of faces then place the IR illuminator some distance to the side of the camera so that facial features create shadows on other parts of the face and thus create some depth to the image.
     
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