I’m sure there was a good reason Tak chose to put two ED elements in the TOA, not just marketing. I’m also sure it’s a mistake to simply extrapolate that to mean more ED elements make a telescope better. What makes a telescope better is a well though out design that has been well executed—whatever the materials chosen for the glass. Just using the “best” materials is not enough, any more than the “best” ingredients are enough when cooking. Trust me, I can make a really lousy meal with really good ingredients. Do it all the time. The glass is one component. If the design is a good one (well suited for the purpose with achievable tolerances). If the materials are good. If the machining is accurate. If the multi-coatings are good. If the figure is good. If the polishing is good. If the assembly is good and the optics are properly spaced and aligned. If all this happens, you get a good scope.
We tend to obsess over the choice of glass because it is something that shows up in a spec sheet. We can evaluate it. The other factors? We can’t judge them except by buying, using, and evaluating the scope. So we fight over glass.
Hopefully the manufacturer of this 140 will do a good job on all the aspects I mentioned (and probably several others I didn’t think of) and the telescopes will be right up there with AP, Tak, TEC, LZOS, and others. Only the experiences of owners will tell us. A spec sheet won’t. Spot diagrams won’t. They can tell you whether the design, if well executed, is suitable for the purpose. That’s about it. This scope is clearly aimed at imagers. The specifications look fine. Don’t worry about the glass. Don’t worry about whether one ED element is better than two. Ultimately, the care taken in manufacturing is much more important.
Edited by Jared, 16 October 2019 - 05:00 PM.