Blue Snowball:thought that the Radial Guider would work well for shooting planets
I also use the Lumicon (2") OAG for long exposure photography with my cassegrain, it works well for that purpose , but you don't need an OAG, a piggybacked guide scope, or any other guider for planetary photography. Just attach your camera to the visual back, or to a barlow inserted into the back, point at the planet, and start shooting.
A "flip mirror" device can be helpful for aiming the scope. Several manufacturers' make these, but they're not required either.
The biggest benefit, for planetary photos, if you want to spend some money, is a webcam with an appropriate 1 1/4" nose, and a copy of Registax.
Robert
www.galacticphotography.com