brandon_turner1 Posted October 11, 2006 Share Posted October 11, 2006 I just bought one of these <a href="http://www.goshotcamera.com/product/FLT00358BIR760">filters.</a> Can someone please explain to me what the 760nm means? Also, is this what I want for basic B&W IR photography with my 20D? Link to comment Share on other sites More sharing options...
jhenry Posted October 11, 2006 Share Posted October 11, 2006 The small range of frequencies that we can see is called the visible electromagnetic spectrum. Waves of light are measured in wavelengths or nanometers (nm), the length determining its color. Wavelengths of visible light range from 380nm to 760nm. The visible colors from shortest to longest nm are: violet, blue, green, yellow, orange, and red. Ultraviolet radiation is situated below 380nm. Infrared radiation has a longer wavelength than visible red light, that is above 760nm... Link to comment Share on other sites More sharing options...
jhenry Posted October 11, 2006 Share Posted October 11, 2006 so my guess is that this filter blocks the visible light and catch what's above 760nm, that is IR... Link to comment Share on other sites More sharing options...
leicaglow Posted October 11, 2006 Share Posted October 11, 2006 Yes, it's for shooting IR, but 760nm isn't blocking all the visible light. You need something in the 920nm range to do that, but it should still give some great effects. You'll need to use a higher ISO or longer exposure on a tripod to see the image in IR though--and that's assuming the 20D's built in IR filter doesn't cause problems. Link to comment Share on other sites More sharing options...
stephen hazelton Posted October 11, 2006 Share Posted October 11, 2006 The "nm" is nanometers, so 760 nm = 0.000760 millimeters, if that helps. Link to comment Share on other sites More sharing options...
alex_lofquist Posted October 11, 2006 Share Posted October 11, 2006 ...or 7600 Angstroms! Link to comment Share on other sites More sharing options...
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