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jhg

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Everything posted by jhg

  1. jhg

    axis 2120 and night vision ?

    I think most normal lenses should pass Near Infra Red NIR (both 850nM and 940nM) as well as visible light but bear in mind that the focussing will be different. If you look at good SLR lenses you will see a red focusing line for use with IR 'light'. What this means is that if your cam's ccd (the retina) is allowed to be sensitive to both IR and visible light at the same time, you will get a double image when using during daylight (depending upon the amount of IR around) 940nM will be worse as it is further away from the visible spectrum. This I think is the reason why there is an IR filter built-in to many lenses which you can often remove. As an aside, Sony used to market camcorders with a switchable IR filter for night use.
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