Arnt has it right. A couple things to make it easier to see the stars to focus in live view at 10x:
- Make sure you have eposure simulation set so you can see the light of the star in live view.
- You can adjust ISO and exposure higher so you can see the star in live view better.
- Start with the focus on the lens all the way to infinity and then back off a small amount in live view until the star is sharp.
- Manually focus.
- You can get real close if you focus on a far away light or moon first.
- Once you have the star focused sharp; turn live view off, make sure the lens is set to MF, and then make sure you do not bump the focus ring.
Have fun, and post some of your results.
Pat