Not being a photographer I am doing a little studying on the topic to get a handle on the physical camera.
I found this calculator that may come in handy:
thanks Rerender, that should be really helpful for thosel who all in a sudden have to learn real photography (like me)
cheers!
Harry
hey thanks a bunch eric!
Maybe this table with the two priorities could go in a handy script hey? 
Lele
wow, thank you Eric!
thanx eric
a.