daryl In other words the guide scope and main scope must be aligned together, Is there a method for aligning the two scopes?
Make use of Euclidean geometry re: parallel lines.
Make a target on a sheet of paper that has two crosshairs (or two large dots). One crosshair is for the main scope, and the second crosshair is drawn so that its center is offset from the main crosshair by precisely the amount the optical axis of your guide scope is away from the optical axis of the main scope.
Place this target across the room (as far as you can, and with the correct orientation, and as perpendicular as possible to a beam of light from the target to your telescope), or, on a wall if you are outdoors. Try to make the height of the target close to the height of your two scopes.
By slewing the mount, center the telescope (turn on any crosshair tool in the image capture software) so that the main target crosshair lines up perfectly with the crosshair of the main camera. Make sure tracking is turned off, and use a very slow slew speed to do the centering.
Once this is done, do not again touch any slew buttons.
Connect the guide camera to the image capture software. Now, adjust the guide scope's tube ring so that the the target for the guide camera on the sheet of paper is aligned with the imaging software's crosshair.
This should get you close enough. And probably more accurate than using a far away tree (unless you can also guess the guide scope offset amount) even if there is no breeze.
Chen
