Hi, I just found your www.pencilofrays.com website on lens design a few days ago. I have played around with Winlens/Qioptic at an amateur level for quite a few years, but there is a lot that I still need to learn, and I am hoping that your tutorial materials will be a great help. So far they are looking promising. By the way, as a specific question, do you have the design parameters for the famous Zeiss 58mm f/2 Biotar, including glass types, surface definitions, and spacings? That was one of my favorite lenses, and it would be interesting to see what it looks like in simulation.