I have discovered something about the 10" f/4 Newt. design:
There is a Russian guy on
the Cloudy Nights forum who wins many competition called Oleg Bryzgalov.
He is using a
Tevevue Paracorr-2 coma corrector with 55mm of back focus on a 10” f/4 Newt.
It shows that a 2” focuser can be used for a KAF8300 sensor..
He has a 79 mm secondary mirror. ( 3.1” )
see here:
http://www.cloudynights.com/topic/48...t-submissions/
https://www.flickr.com/photos/olegbr/15987950961/
The RCC1 that I want to use is not quite as good but may still work.
At least it has a longer back focus.
It would not be as good as an ASA Newt. with a 3" focuser.
Now - back to the 12" f/4 -
still studying that.
cheers
Allan