You might has read this ?
On the drawbacks.
Well, it’s very hard to do one, especially if go very thin.
If not slumped one can get a core that are machined meniscus, but it’s very hard to place it down when polishing.
Then the mirror cell etc.
This 25” has a slumped meniscus plate glass mirror and its little over 1/2” thick and use a plywood triangle 9 pt cell and edge support is at 90 degree.
As meniscus and a deep sigatta as f/2.6, so the idea it’s a eggshell and also that its basically thicker vs edge thickness/sigatta, comparing to a traditional plano. ( whatever that is the case I can’t say )
This telescope design is very light and compact in design and its foot on the ground observing.
At low power as I seen it at its really cool as wider field.
I can’t say on Strehl and maybe this instrument came to be by using Ethos 21/17 mm EP and max pupil.
High power is little over 500X ( E3.7 mm ) but of course a Powermate can be used.
Its also has a rather small secondary at 5.5” and that is because the focuser and the CC intrude some.
This scope has no fans.
If it can compete with a optical glass and more ratio and maybe a machined core at ex f/4.5 might be a non meaning discussion.
It shore it’s a hard work do one of these and this is ATM at its best.
More app is to come I read !
Edited by hakann, 15 January 2020 - 10:47 AM.