We can “see” light between 380 and 700 nanometers, but what happens at the egde and just after that? I mean, when we approach the limit like 699-700-701-705…
Does it turn completely dark/invisible/something else immediately or is there some kind of gradual change?
Is it the same on both ends?
In: 17
If you graphed the spectral sensitivity of the average human eye, it’s not like a solid bar from 400-700nm. There are peaks in blue, green, and red wavelengths that rise up and fall off and overlap with each other. Sensitivity falls of to near nothing at the ends of the visible spectrum so most folks can’t see near UV or IR at all.
I do a bit of photography so I have various filters I use. The Hydrogen alpha filter I use to photograph emission nebulae allows only light at 656nm though, and it’s pretty dark to try to look though even out in the daylight because the eye isn’t very sensitive to longer wavelengths of visible light. My 720nm IR pass filter is completely opaque to my eye, but my modified camera will very gladly see through it.
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