[alpal]

Originally Posted by Bassnut

I sort of agree RC designs have been "superseded" in that similar performance can be obtained on "corrected" designs for way less money eg CDK.

But "No matter what system you buy it always needs a corrector" is not quite correct really. My RC set up has no glass at all, mirrors only. A flattener (glass) is recommended for larger sensors on my RC, but I get away without one. Assuming your correct that glass introduces aberrations, then thats one problem I dont have, so that must be an advantage on an RC not available on other designs I guess.

I dont know if not having glass makes any other difference. I focus every 2 weeks or so, does glass itself cause focus change with temperature?.

I wonder if a flattener would give you even sharper images
especially off axis?

Focus every 2 weeks?
I thought some people were using FocusMax & changing focus with
every filter & sometimes between frames?
Those electric focusers can have steps smaller than 5 microns.

I don't know about focus with a flattener & other glass versus temperatures.