I read somewhere online that one way to test shutter speed is to hook a mike up to your computer's sound card. The computer hears the "click" of the shutter opening...then the "click" when it closes. You just use audio software to plot a graph of the sound and you measure the time between clicks. SO...I have a mike..I have a sound input on my computer... BUT I don't have software that will make the kind of graph that will allow me to measure the time interval between clicks. does anyone know of software that will do this that can be downloaded free?