While The 17.5" Reflector Is Being Rebuilt By A Pro...

I have gone back to the 8" f/7 instead.  This is prime focus :

 

I did an eyepiece projection shot with an 18mm eyepiece along the terminator to try and get the focus right before trying for Saturn:

I didn't have the focus quite sharp enough, and then the smoke from the Bogus Basin fire made Saturn unavailable.  Maybe tomorrow night.