ASA SP Strike Zone

[drh898]

I've done years of fast pitch and just started doing SP 3 years ago. I find calling ball and strikes in SP very difficult. I've done leagues that use a strike mat and that's a piece of cake. Without the strike mat ASA states the strike zone is between the knee and the back shoulder but I have a hard time judging that, especially when the catcher stands back from the plate. I usually call the pitch depending on where it lands behind the plate. Assuming you have a legal pitch, what tips can you give me on how to call balls and strikes in ASA SP? I don't feel I'm doing the game justice.