|
You save weight by shortening the tube.
You're adding weight in the form of a secondary mirror and supporting spider significantly larger than the diagonal of a newtonian.
You're also going to need to add baffles to stop stray light coming obliquely past the secondary and through the hole in the primary (more weight).
I can't help feeling the result will be much the same weight as before, but optically worsened by having a 50% secondary obstruction. You've going to throw away another chunk of aperture off the rim off the secondary, so your losing perhaps 30-40% of the incoming light collected by the 12" mirror.
I can't help feeling you'd do better by leaving what you have alone and spending the $ on a 20 or 25cm f/5 mirror with about the same lightgrasp, and build a smaller and much lighter OTA that won't overload the mount.
|