3ec84287
From: into@oblivion.nothing.com
jogging wrote in news:9948fba4-4800-4f35-b37e-
2d64ec43b796@t15g2000prt.googlegroups.com:
> I don't understand the statement,
> "blue is significantly defocused when red and green are in focus".
> Does it mean different wavelength need different focus
> length to be in focus? White light is composed of
> different colors, so it results in being out of
> focus. Does it affect how we sense the objects when
> we look at them?
When considering the human eye as a 'camera', it's a really crappy
low quality one.
The cornea is a simple lens and suffers from chromatic abberation.
Different wavelengths come to focus at different distances. The
eye/brain system has evolved so that red seems to be the color
the system uses for it's 'autofocus' routine.
Ever look at a distant mercury street light at night and notice
a blue aura around it? That's the extreme blue wavelengths not
being in focus whereas the greens and reds are.
Another dramatic example would be to have three high brighness
LED's, one each red, green, and blue. Have them spaced several
inches apart and then move about 50 feet from them. Note how you
can focus on the red and even green, but blue is a bit harder.
The brain does a lot of image processing to clean up the crappy
signal from the eye. Actually, it's more correct to say that the
processing starts with the nerves in the retina. Up to that point
the eye is just a lousy camera.
Brian
--
http://www.skywise711.com - Lasers, Seismology, Astronomy, Skepticism
Seismic FAQ: http://www.skywise711.com/SeismicFAQ/SeismicFAQ.html
Quake "predictions": http://www.skywise711.com/quakes/EQDB/index.html
Sed quis custodiet ipsos Custodes?
--- SoupGate-Win32 v1.05
* Origin: you cannot sedate... all the things you hate (1:229/2)
|
