[Raytrace] Re: A useful sequence

[Peter Chen]

Hi:
	I went through Peter Smith's suggested sequence.  It worked well and was 
very instructive.
	I had no problem getting up to the Newtonian, Cassegrain, and thru the 
Dall-Kirkham.  However, the optimization routines (Hammer, Golbal)  would 
not converge when going from Dall-Kirkham to RItchey-Chretien when the 
secondary radius, primary and secondary conics were set to 
'variable'.   After several attempts, I found that if I started from a 
Cassegrain and set the merit function to 'ptv spot size' rather than 'rms 
spot size', it converged.
	 So I guess the lesson is that, in raytracing, it helps to know where to 
start.  Am I correct?

Regards,
P.C. Chen