See
https://www.cloudynights.com/topic/6...or-myth/page-3
There’s a link to a Russian optical lab that did the tests, each set of results, interferogram and a photo of the scope (sometimes with owner) are posted. I’ve pulled out the SCT and maks from Meade Celestron Skywatcher Intes and Santel into a spreadsheet, can post it later.
Using the filters you can compare SCT vs mak, Meade vs Celestron etc. Doesnt make much difference if you use P-V wavefront error or strehl.
If it’s a reasonably random sample and I don’t see why it isn’t, it also implies a lot of the claims on CN are balderdash.
It also suggests you’re getting nothing special by shelling out for ACF or HD optics...
Another aspect is that if you omit the 3 worst shockers for each of Meade and Celestron things look decidedly better. But it does confirm they do sell the crap scopes with wavefront errors close to a wavelength !!