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| p.5 #18 · silly inverse square law question. |
Check out the interactive tutorial in the link. It does a better job than my inept artwork ever will.
Slide the color slider all the way to the left to get "white" light.
Set the surface roughness to the far left to emulate a "mirror" surface.
Then as you change the surface texture, the multitude of surface angles begin to change ... which in turn is responsible for the collection of angles of reflection that still follow AI=AR, producing the diffusion of the light spreading out, that people are wrongly trying to attribute to ISL.
If reflected light was spreading iaw ISL ... the light from a 'signalling mirror' ... by the time it reached it reached the pupil of the pilot, it would be too weak for him to see it. Good thing light travels straight, iaw AI=AR ... otherwise a signalling mirror (uniform surface) would be as worthless a sheet of paper (non-uniform surface) scattering light in a plethora of directions.
I hope I don't ever need to use a signaling mirror ... but if I do, I'm glad that reflected light travels straight line, iaw AI=AR and the conservation of energy ... and not ISL ... to help me get a pilot's attention.
Those angles that reflect light back in the direction of the lens will reflect the same amount of energy until something acts upon them ... no matter how far back/close you move the camera from the subject. Barring atmospheric conditions like smog, fog, etc. that acts upon the light, the light continues straight line predicated upon the direction it was reflected, iaw AI=AR.
I realize it is one thing to debate in a cyber-blog, but if you check the source @ the link, you'll see it is in conjunction with FSU. Hopefully they can add a bit of credibility to the dialogue.
Light Science & Magic ... get the book.
Minimal physics ... yet, great practical photographic application properly derived from the physics.
Edited on Nov 11, 2012 at 02:39 AM · View previous versions