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Thread: soundcard shutter tester works great!

  1. #1

    Join Date
    Aug 2006
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    soundcard shutter tester works great!

    Just made a shutter tester out of a $1.50 infrared photocell from RadioShack and my computer's sound card. Tested my Speed Graphic lenses. My 90 Optar measures too fast in most settings (.736 at 1 sec. and 1/50th right on). My 135 Optar measure slow (1.3 in 1 second and pretty accurate for the other speeds. My newly purchased 210 Rodenstock in Copal was very accurate at .905. I couldn't accurately measure the top 1/400th speeds of the shutter as they showed the same speeds as the 1/200th settings. Now for the fun part. I measured my focal plane shutter which i have never ussed. The 1/30th was off almost a stop slow but the rest of the speeds were more accurate than the leaf shutters and It seems I could accurately measure the 1/500 speed but not the 1/1000 speed. The test revealed why some of my Velvia film came back underexposed with the 90 lens. The 1/25th was especially fast and that would be the speed used in full brightness situations.

  2. #2

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    Oct 2006
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    Re: soundcard shutter tester works great!

    Could you share how you did this?

  3. #3

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    May 2006
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    Re: soundcard shutter tester works great!

    my suspicion is that he recorded the sound of the shutter opening and closing on the computer and identified the peaks and troughs of 'which actions registered where' and then just read the time off the display with graphical waveform editing software.

  4. #4

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    Re: soundcard shutter tester works great!

    I'm getting ready to make one too. It's a real simple schematics - one phototransistor, one resistor, a single 1.5 V AA battery and a switch, all in a serial connection with a mic input on the PC sound card. Total cost = approx. $5.00. OK, $10.00 if you want to get fancy.

    When the light is shone through the lens and the shutter fires, the phototransistor generates a pulse very similar to that of the microphone. The sound card records it as a function signal. The duration of the signal as measured in a sound-recording program - i.e. the length of the signal wave - represents the shutter speed.

    It actually sounds much more complicated than it really is...


  5. #5

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    Re: soundcard shutter tester works great!

    One more thing - if you want to really test the focal plane shutter, you can use two phototransistors appropriately spaced and connect them to the sound card using a stereo cable. A PC sound card IS stereo, after all. That way, first and second curtain can be pretty accurately measured, as there would be two peaks for opening and closing.

  6. #6

    Join Date
    Feb 2005
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    Re: soundcard shutter tester works great!

    Quote Originally Posted by Marko View Post
    I'm getting ready to make one too. It's a real simple schematics - one phototransistor, one resistor, a single 1.5 V AA battery and a switch, all in a serial connection with a mic input on the PC sound card. Total cost = approx. $5.00. OK, $10.00 if you want to get fancy.
    Would you post a part number for the phototransistor and a supplier, and the resistance for the resistor.

  7. #7

    Join Date
    Jul 2004
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    185

    Re: soundcard shutter tester works great!

    I've found that you don't need the battery. I took a phototransistor and resistor from radioshack (sorry, not sure the part no.), soldered them onto a small piece of breadboard and used an old computer microphone jack. There is a public domain wave analyzer called audacity which you can use to time the peaks between opening and closing. The waveform is small but readable.

    Bill

  8. #8

    Join Date
    Aug 2006
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    69

    Re: soundcard shutter tester works great!

    The phototransistor I used was the only one Radio Shack had in stock. They call it an infrared phototransistor. I used a 4.7kohm resistor and a 1.5 volt battery that was probably getting weak. Plugged it into my soundcard mic input and recored the sound with SoundForge. Maybe one could get by without the battery. I do know that most sound card mic inputs aren't stereo but use one of the legs to supply power to a microphone. I just plugged an 1/8th inch mono plug into it and it worked ok. Probably shorted out the mic power supply part but it's probably protected with an internal resistor in the sound card. Just do a search on google and you'll come up with plenty of schematics. Some use a capacitor to tame things a bit I suppose but I tried it without and it worked ok. Maybe with the capacitor the pattern would be easier to read. I wonder whether one could get by without the reisistor and plug it into the line level input of the sound card instead of mic input. I just cut out a 4x5 foam core and put the phototransistor in the middle of the board through a hole. Used a flashlight shining through the lens with aperature wide open. The 90 6.8 lens showed a very small spike in the soundwave so it was harder to read. Had to really zoom in on the wave with the zoom features of the program.

  9. #9

    Join Date
    May 2006
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    Re: soundcard shutter tester works great!

    See http://www.largeformatphotography.in...ad.php?t=21789 for the post containing links to diagrams.

  10. #10

    Join Date
    May 2006
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    271

    Re: soundcard shutter tester works great!

    does it works with apple computers ?

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