URL explaining WHY large heads/reflectors have better throw?

[Esko]

True, but in mathematics/physics you cover the idealistic cases before the "actuals" and in an ideal world, any sized perfect parabola will have a perfect focal point, and if light is emitted from that point, a parallel beam...etc etc. the theoretical stuff sticks much more than the actual in most cases. From my experience, engineers fall into two categories - those who have an amazing theoretical/equations side and those who are much more practical. I suppose the theoretical ones should've gone into physics/math though.

True, too. This reminded me of Richard Feynman and his book "Surely you are joking, Mr Feynman!". In the book, he was briefly a visiting physics lecturer in Brazil. His students knew the theory very well - in theory. They had just memorized everything, without understanding the subjects and with no skills to put the knowledge into practice or recognize the phenomena in real life situations. At the end it was clear that even the author of their physics book - a highly regarded scientist in his country - had never done the experiments described in the book.

It was a good book (the Feynman's one that is).

Another thing that came to my mind was this comic.

Also tried to do a few quick searches in Sciencedirect and Google Scholar but didn't find any specific article for OP.

 

[fishndad]

rofl, the funniest thread ive read on cpf

 

[djozz]

Actually, very basic theory of optics applies very well in the practice of flashlight-making. Even the most cheapy toy-camera needs better optics than a flashlight. Optical complications such as edge-unsharpness and chromatic/spherical abberations of lenses/reflectors are not much of a problem, A blurry image of the led is even desired (soft hotspot), so leds are placed just out of focus, and the optical quality of the reflector is often even intentially ruined to obtain this (OP-reflectors). As long as reflectors are more or less parabolic with the right curvature, and the led is more or less neatly in the focal point of it, your beam pattern will be alright.
So IMO there is a lot of phyics theory that is not easily apllicable in practice, but for flashlight design, the basic general lens equation is more than adequate.
djozz

True, but in mathematics/physics you cover the idealistic cases before the "actuals" and in an ideal world, any sized perfect parabola will have a perfect focal point, and if light is emitted from that point, a parallel beam...etc etc. the theoretical stuff sticks much more than the actual in most cases. From my experience, engineers fall into two categories - those who have an amazing theoretical/equations side and those who are much more practical. I suppose the theoretical ones should've gone into physics/math though.