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Take a look at the full spectrum chart below and you can see that visible light starts about 350nm ( Nanometres ) and fades away at around 750nm.  Anything above or below these limits is simply just not visible to the naked eye.  The sensor in virtually every Compact and DSLR Camera has a far wider scope then the visible spectrum,  plus one or two other  maladies.

To make your Camera usable the manufacturer has to place a small square of greenish glass in front of the sensor that will cut out all or nearly all Infrared rays and limit ultraviolet rays.  This small piece of greenish glass is called the HOT MIRROR and balances out the sensor to enable you to take what I would hope you would think are pleasing images.

The HOT MIRROR must be removed if the conversion is to be a success,  there are one or two cameras such as the NIKON D70 that have a weak HOT MIRROR and with patience and a tripod can produce very pleasing Infrared Images but the D70 is in a class of it's own but could get you into Infrared work very cheaply together with a tripod and 5 to 10 second exposures.

With the Hot Mirror removed and a suitable filter installed you can start to see everything in a different light,  with white grass and white leaves on trees,  if you have a DualBand filter on then colour appears but only to a limited extent that the filter allows.  Please see the gallery.

Where does this radiation come from,  the major source is solar ( Sun )  secondary sources include Tungsten lighting,  a suitably converted light meter will reveal Hot and Cold spots,  and often not where you think they should be.

Infrared can penetrate certain materials suck as plastic so street signs and sign writing can become obscure and possibly left out of the frame so as not to confuse matters,  it cam also penetrate paint so one can see anything hidden under a caot of paint,  so if you happen to have done a whoopsy and covered it up with a fresh cout of paint don't worry it will still be visible to the Infrared / DualBand Photographer,   even old Masters paintings can reveal their initial use.

Evening light and the last rays of Sunlight can hold a significant amount of Infrared to make some remarkable images when all around looks a black as hell.

Visible Spectrum


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