I have just purchased an Orion Thin Off-Axis Guider (TOAG). This enables me to contain both the main DSLR and CCD cameras on the same focuser, freeing up my guide scope. Testing has been positive thus far.
The TOAG is solid metal: it is very sturdy and will handle the load of a more solid CCD camera such as my Meade DSI II. This is just what I needed for my big Newtonian. “It’s ideal for use with Newtonian reflector telescopes which have limited “back focus” travel” (Orion, 2013). My Schmidt-Newtonian does indeed have limited focuser travel and this item has fit the need quite well. I assembled the item and pointed the telescope out the window and targeted a terrestrial target (a telephone pole). The focus of the two cameras did not match: after adjusting the TOAG I was able to obtain focus on the CCD. It did take some experimenting with the extra included spacers: “[a] C-mount to T-threads adapter, Canon DSLR bayonet adapter, Camera T-adapter, ultra-thin M48 male to T-adapter female adapter, 3mm Coma-Corrector spacer, 18mm spacer, and a 2″ nosepiece” (Orion, 2013) are included to get the right fit.
Now that piggy-backed refractor scope is freed up for visual observing.
Orion. 2013. Orion Thin Off-Axis Guider for Astrophotography. Retrieved November 17, 2013 from http://www.telescope.com/Orion-Thin-Off-Axis-Guider-for-Astrophotography/p/102812.uts