I fancy trying to put one of these together but can I rely on the accuracy of one of these home made devises? Any experiences?
muchas gracias
http://www.davidrichert.com/sound_ca...ter_tester.htm
I fancy trying to put one of these together but can I rely on the accuracy of one of these home made devises? Any experiences?
muchas gracias
http://www.davidrichert.com/sound_ca...ter_tester.htm
The rise and fall times of the phototransistor are 3 millionth's of 1 second.
The sound card and Audacity samples the signal 44,000 times per second by default.
These figures should allow you to time a 1/500th second shutter speed to reasonable accuracy, say to within about 1/60th of a stop.
Is that good enough for your color transparencies?
They're accurate enough for photographic purposes.
Greg Lockrey
Wealth is a state of mind.
Money is just a tool.
Happiness is pedaling +25mph on a smooth road.
Smashing guys thanks.
Now to get the bits a bobs and start soldering. Me no need no stinking overpriced Calumet tester
Instead of building an optical set-up, would it be possible to use a microphone with the same software.
I assume since this is simpler and not being done that there must be a downside?
I only need to test speeds from 1 to 1/30.
Last edited by Ron Marshall; 23-Nov-2008 at 18:39.
I had read somebody suggest this and tried it once with the very loud shutter of my Fuji GW690III. I may not have persevered sufficiently and my microphone was the worst possible, but I was never able to differentiate the opening and closing of the shutter. I am not sure that I was using Audacity at the time either.
I would suggest that you give it a shot. It sure doesn't cost a lot to try.
I wouldn't go with the microphone. How do you know what part of the noise of the shutter actually coincides with the opening and which part goes with the closing? If you record a shutter well, you will hear much more than 2 clicks.
I've used the Audacity program with a very cheap microphone and found it more than adequate for shutter measurements longer than 1/250 sec. I also have a photo transistor apparatus similar to the one in the project diagram referred to in the original post. Instead of connecting to audacity, I connected it to a very high speed digital storage scope. I found the slew rate (speed) of the photo transistor to be a problem at speeds faster than 1/500 sec -- but still usable.
Back to the Microphone... for shutter speeds longer than 1/125 I would definitely use the microphone. I even used it with my di$%al SLR camera and could see in the Audacity wave form where the mirror raised, shutter clicked (start and stop), and mirror returned. The lesson here is that you get a little more information with the microphone than the light sensor.
Regards,
Bill Riley
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