Rowena to help your focus you might want to consider using a hartmann mask to place over your objective when focusing. Really easy to make and they make a big difference.
http://www.iceinspace.com/forum/show...hlight=hart%2A
Also 10 sec exposures will be far too long to get anysort of clarity. Turbulance in the atmosphere over that time will blur any detail right out of the image. Try a maximum of around 1/5 sec with a faster ISO (800 at least though the graininess of the image will increase)
Good luck