Quote Originally Posted by Lee L View Post
Should have thought to mention:

You can use a diffraction mask in front of the lens to create diffraction spikes, making it easier to see when you're in focus on a star with an autofocus lens and SLR body. You can purchase them online or make them yourself. Here are links to two different styles most commonly in use these days:

http://en.wikipedia.org/wiki/Bahtinov_mask
http://en.wikipedia.org/wiki/Carey_mask

But I'm not sure how well these would work on a wide angle lens.

Lee
This is very interesting