I just noticed, if you google that phrase, I found my RHP question was #3 on the list of responses to that phrase!
I was trying to figure out where our sun's first focal length lay and used Einstein's gravitational lens equation and it turns out to be about 52 billion miles or 83 billion Km from the sun.
I see from the RHP post that Joe Shmo answered that question way back in 2008!
Radians are neat because to find the mutiplier for distance, just invert the radian # which in this case is 8.4842E-6 radians, invert to 117,865.6, the multiplier used to fix the distance, using half the diameter of the sun, 440,000 miles or 704,000 kilometers times the multiplier off 117,865.6 = 51.8 billion miles or 83 billion Km. That is just the first focal point however, a line of an infinite or nearly infinite number of points follows further out.
But only if the wavefront of energy impinging on the sun is flat.
That doesn't quite happen with the curved wavefront of real stars.
Hey Joe, thanks for the help! I decided to get back into this and finish my work on this subject which I had put in a lot of time!