Stay focused with the BAHTINOV MASK.
This great little gizmo is easy to make and will help keep those stars nice and sharp when your taking pictures with your SLR camera on your telescope.
To use it simply find a bright star in your telescope finder and get it lined up in your camera view finder.
Next put the Bahtinov mask on the end of your scope and focus in on your star till it looks sharp to you if its tiny in your view finder as it is in a canon 350d never mind just do a rough focus and take a picture.
Then zoom in on the picture and take a look,it should look like this with the middle spikes bang in the middle of the star, if the middle spikes are not in the middle or off to the side slightly refocus and try again. If your camera has live view and zoom this is easy to see if not focus take the picture review until it looks like this.
Ok you are now focused and can start taking your photos its that easy and a great time saver. Making the Bahtinov Mask is also easy I made mine from an old plastic file folder just grab a template of the web there's loads of them out there or if you cant be bothered then buy one for about 14 quid. Making one is more fun.