Here is another one that I just typed up that might help also.
As far as the focus there are a couple of things you can do. First is do not have the camera perpendicular to the glass, it can focus on the glass instead of the coral. Have the camera at an angle to the glass. Also if you really want a good pictures of your corals set the camera for the highest resolution. That way you can crop the picture where you want it and you will get a good picture. Also since it is a digital camera and the pictures are cheap, practice, practice, practice. For instance my avatar is from when I chased my son around the house tickling him with one hand and snapping pictures with the other.
HTH
Scott
