Mike.....I consider this book essential reading for all ATM's, in fact, for anyone who owns a scope and is willing to accept an honest answer to "How good is my scope, really?" But is has much more information than just the star test, with chapters on collimation, turbulance, sizeing your secondary-basically anything that affects performance. Even after reading it, though, I feel I'm just beginning to understand the star test. Separating edge effects from over/under correction will take some time and experience. But I've learned a lot about the mirrors I make or own. If you are just looking for a casual guide to mirror quality, it may be too advanced. On the other hand, it may open up a whole new window on the hobby of telescope making/using for you. And it's not an expensive book. I suggest you give it a try. Or maybe suggest your local club buy a copy to pass around to members. .....RICH