While working on a Podcast devoted to large format photography, I decided to record the sound of one of my shutters firing to use as a sound effect in the intro. When I did that, I immediately realized that I had a graph that showed me how accurate my shutter speeds were. I used the free audio program, Audacity, which only took me about 15 minutes to figure out how to use.... and I'm slow! I then tested all of my large format shutters and the results were very good up to speeds of about 1/60th of a second which is fine because I rarely, if ever, use speeds faster than that anyway. Fortunately, I had just received a lens back from S.K. Grimes that was in for a CLA and the results that I got with Audacity matched perfectly the data sheet that Grimes included with the lens, confirming the value of this method. Someone then asked me if it would work with focal plane shutters so I gave it a try. I did not expect it to work but I was very suprised to find out that it worked extremely well for my 35mm shutters too but, again, mainly for the slower speeds. Attached is an image of a test. I apologize for the double graphs for each speed. It was recording in stereo so there are two channels. I will have to find out how to shut that off next time. Of course, the graphs can be scrolled up to line them up with the timeline at the top and also scrolled left-to-right to align it that way (as I have done in this example.) The graphs can also be expanded or contracted as much as you like to study them in greater detail. You almost certainly could do this with any audio editing program. For me, this is a real boon because I don't have a shutter tester and I am never really sure if my shutter speeds have drifted. For that reason, I generally send them in for a CLA every year or two even though they may not need it so this saves money and allows me to be confident that I know the actual shutter speeds of my lenses. Now I can test them in just a minute or two! I hope someone here finds this method as useful as I have. I have no doubt that other people have stumbled upon this or a similar method but I hadn't so, hopefully, there are others who may find this useful. You can download Audacity for free at http://audacity.sourceforge.net/ The attached graph should be self-explanatory. This is the results from a test of a large format lens for shutter speeds of 1 second, 1/2 second, and 1/4 second. Of course, you can test all shutter speeds and simply scroll up and down to them with the program.