Thanks
I use an OAG made my Aeroquest machining
http://www.aeroquest-machining.com/page9.html
My unit
http://www.users.on.net/~josiah/focuser/IMG_9933.jpg
http://www.users.on.net/~josiah/focuser/IMG_9937.jpg
Internal view showing the pick off prisms
http://www.users.on.net/~josiah/focuser/IMG_9935.jpg
As the pick off prism are ahead of any filters I get unfiltered guide stars, and in addition to 360 degree rotation about 1/2 a degree or so of radial movement (by turning the adjustment screw at bottom) can be done. Disadvantage is that guidestars especially those at outer edge of acessable field are comatic.
I got this as I was sick and tired of flexure with a 75 mm refractor ruining images.
I wished I could afford one of those big Sbig cameras with the separate guide unit, or even a cheaper unit to just use for guiding like Pauls and a mount that accepts autoguide input
.
Scott