Where to begin...

[E. von Hoegh]

Of course, the trouble with the Audacity test is that you are measuring the duration of the sounds the shutter makes, rather than the amount of time the blades are actually admitting light.

Not to rain on anyone's parade, but it isn't an accurate way to test a shutter except at the very slowest speeds.

[gliderbee]

Of course, the trouble with the Audacity test is that you are measuring the duration of the sounds the shutter makes, rather than the amount of time the blades are actually admitting light.

Not to rain on anyone's parade, but it isn't an accurate way to test a shutter except at the very slowest speeds.

The moment the blades are open, there's only the noise from the shutter itself.

If you first select the part where the noise is recorded, and then from the menu "zoom in on selection" (Ctr-E, I'm translating from the Dutch version), you can see very clearly where the blades snapped open, followed by a more or less continuous, low sound recording from the shutter, and then the blades snapping shut again.

Stefan.

[E. von Hoegh]

Sorry, but years ago I put a microphone on a shutter and watched the trace on an oscilloscope. Quite a lot happens soundwise leading up to the blades opening. The closing of the blades is cleaner. A shutter tester that measures the light coming through the shutter is really the only way to do it properly. As I pointed out, the Audacity program will only work accurately on the slowest speeds where the duration of the blades being open is several times as long as the other sound events.

Edit - Two people, posting above, have tested their shutters using this method. The results are that one shutter is 8% off at 1 sec, and "spot on" at all other speeds. The other shutter is good "within a few hundredths" at all speeds (if it's within afew hundredths at say 1/400, it isn't very good). I think this makes my point for me; I've tested shutters from brand-new to 100 years old. NONE, not one, was "spot on" at any but the slow speeds. My testing rig for leaf shutters uses a phototransistor and an oscilloscope with calibrated sweep. It is accurate to a few millionths of a second, according to frequency standards from NIST.

[gliderbee]

Well, you apparently know more about it then me, but still, I think it's useful to have an idea about the performance of the shutter; after all, I don't care if it's 1/400th or 1/405th (and that's what I meant with a "few hunderdths" off; I see now that I put it the wrong way ).

Stefan.

Sorry, but years ago I put a microphone on a shutter and watched the trace on an oscilloscope. Quite a lot happens soundwise leading up to the blades opening. The closing of the blades is cleaner. A shutter tester that measures the light coming through the shutter is really the only way to do it properly. As I pointed out, the Audacity program will only work accurately on the slowest speeds where the duration of the blades being open is several times as long as the other sound events.

Edit - Two people, posting above, have tested their shutters using this method. The results are that one shutter is 8% off at 1 sec, and "spot on" at all other speeds. The other shutter is good "within a few hundredths" at all speeds (if it's within afew hundredths at say 1/400, it isn't very good). I think this makes my point for me; I've tested shutters from brand-new to 100 years old. NONE, not one, was "spot on" at any but the slow speeds. My testing rig for leaf shutters uses a phototransistor and an oscilloscope with calibrated sweep. It is accurate to a few millionths of a second, according to frequency standards from NIST.

[John Rodriguez]

Sorry, but years ago I put a microphone on a shutter and watched the trace on an oscilloscope. Quite a lot happens soundwise leading up to the blades opening. The closing of the blades is cleaner. A shutter tester that measures the light coming through the shutter is really the only way to do it properly. As I pointed out, the Audacity program will only work accurately on the slowest speeds where the duration of the blades being open is several times as long as the other sound events.

Edit - Two people, posting above, have tested their shutters using this method. The results are that one shutter is 8% off at 1 sec, and "spot on" at all other speeds. The other shutter is good "within a few hundredths" at all speeds (if it's within afew hundredths at say 1/400, it isn't very good). I think this makes my point for me; I've tested shutters from brand-new to 100 years old. NONE, not one, was "spot on" at any but the slow speeds. My testing rig for leaf shutters uses a phototransistor and an oscilloscope with calibrated sweep. It is accurate to a few millionths of a second, according to frequency standards from NIST.

When you're looking at the sound file it's very easy to see where open and close are when you zoom in. Your accuracy will be based on how many decimal points out you record the findings at. I've tested all of my shutters and none had 0% variance, but all were within 15%. I only test out to 1/60, as I rarely shoot faster than that and Audacity only zooms in on the file so far (I could use Logic instead but I'm too lazy).

What this won't tell you is whether or not your aperture settings are correct, for that yes, you'll need to measure the light. However, if you want a quick and dirty method to partially test your lens for free, this works.

[Jim Jones]

Accurate testing of my many shutters is one of those often postponed chores, but I'm with E. von Hoegh. Another often overlooked consideration is the aperture setting. At high shutter speeds the aperture can make a big difference due to reduced shutter efficiency.

[E. von Hoegh]

The Audacity test and similar tests are a kludge at best. Different shutters have different sound events. If you don't believe me, get a bunch of different shutters and look at the display. There's no traceable calibration for Audacity, either.


What we need is a reasonably priced and easy to use shutter tester.