Quote:
Originally Posted by Merlin66
Hmm
I still stand by the analysis I did between the f5 conic surface and a cylinder section.....
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Hi Ken, I didn't run the exact numbers but when you slice a cone you get an ellipse. When you slice a cylinder you also get an ellipse. So you can always offset a cylinder with a diameter to match the minor axis of an ellipse generated from a cone. The secondary offset actually does exactly that with the light cone. I suspect primary blanks are also cut from cylindrical bars of glass as it's far more practical?