Yeah, I watched Fagin figure my optics and it was a long drawn out process. My patience is more adapted to mechanical design and not optical testing, so watching him was an education. He recognized the slight zone he left in my primary then polished that out along with figuring the secondary as he explained the two mirrors were the whole system. It takes a lot of time. After he finished I really paid attention to al the mechanical details, tweaking everything up until it was perfect.
Before going from f/16.5 to f/30 and tweaking everything up the telescope performed very well; but was missing the sharpness and image contrast that Parker’s Newtonian gave us. However, after that my scope really worked great and was every bit as good as his scope; plus I could use larger eyepieces without a Barlow with great eye relief and still observe Mars up to 1,000x. Our seeing was usually that good.
Wished I would have Danny J. make my 16” into Cass; I would still be swatting mosquitoes, chasing off critters and enjoying sitting under the scope instead of hanging off a ladder. Besides the challenge and fun of making that scope would have been well worth it. An f/50 is a stretch, but for planetary observing that works out well. We used 24” scopes at f/75 in the Lowell’s planetary patrol and images of Mars or Jupiter at prime focus are really good. A 24” Cass with 1.6” secondary!