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  1. #11

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    Too bad ole' Bix left us so early. You sound like you know what you're doing. Just for edification about phonographs--no the diameter of the idler wheel doesn't factor in, but its condition does. It either gets hard and slick, or it gets gooey. So I have to send off idler wheels and Rochelle salt cartridges for rebuilding. I re-cap the chassis, check and/or replace tubes, and put it up on the Hickok for re-alignment. Typical procedure.

  2. #12
    Jim Jones's Avatar
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    In the days of analog television, we did quick checks of high shutter speeds by watching the TV screen through the shutter with the lens removed to observe how much of the image appeared bright. The full TV screen equaled 1/30 second; half a screen, 1/60 second, and so on. It was certainly accurate enough for most B&W photography.

    As for the 60- or 50-cycle ripple from AC lamps, using low voltage high current lamps reduces this. 12 Volt automotive lamps powered by an old computer power supply eliminate the problem entirely.

  3. #13

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    I use a photodiode press fitted in a block of acetal. A very small drilled hole forms a tube to limit the angle of view. The block is pressed against the ground glass.

    The light source is a floodlamp, its 120 Hz ripple allows a handy way of double checking the scope calibration.
    The light is adjusted so the photodiode stays in its linear region when it comes off dark current.
    The thing is sourced with a 9V battery and a storage oscilloscope measures the bias resistor voltage.

    I have tested a few old shutters and I think the tester is quite accurate, showing penumbra too.
    It also works on the curtain shutter of the Speed graphic.


    Curiously, although the Speed Graphic rear shutter is completely clockwork and the camera has no batteries, I have observed the rear shutter emit a solid electromagnetic pulse when it starts to move. That sometimes triggers the scope early. I have not figured out what causes that, maybe some part in the clockwork is magnetic.
    Attached Thumbnails Attached Thumbnails a3022312Sc.jpg  

  4. #14

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    Funny you're using an old record player. Once upon a time we used the tv scans to time shutters.

    I converted to an ociliscope n triggered a freeze tracer i built from popular electronics in the 70s. Still works fine but its such a pita to drag out my techtronics scope that weighs a ton n browns out the neighborhood when i fire it up!

    Ive since built the photo diode used through my computer's sound input n recording program. Its as accurate as my scope n has been just as reliable as my old calumet shutter tester now collecting dust on top of my osciliscope.
    Anyone can make a Digital print, but only a photographer can make a photograph.

  5. #15
    omaha's Avatar
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    I'd be interested in seeing the test shots.
    I shoot digital when I have to (most of those shots end up here) and film (occasionally one of those shots ends up here) when I want to.

  6. #16
    Bill Burk's Avatar
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    I've finished crunching the numbers and have come to the conclusion that I will keep the numbers from the electronic test for the slow speeds. The turntable test was amusing but not precise. The exposure test (18% gray patch) gives me new shutter speed values for the high speeds.



    What I've noted for my camera:

    Setting: 500
    Degrees: 2.5
    Speed by Degrees: 1/184
    Speed by Exposure: 1/125
    Speed by Electronic: 1/160

    Setting: 250
    Degrees: 3
    Speed by Degrees: 1/154
    Speed by Exposure: 1/80
    Speed by Electronic: 1/81

    Setting: 100
    Degrees: 6
    Speed by Degrees: 1/77
    Speed by Exposure: 1/50
    Speed by Electronic: 1/40

    Setting: 50
    Degrees: 13
    Speed by Degrees: :1/35
    Speed by Exposure: 1/25
    Speed by Electronic: 1/22

    Setting: 25
    Degrees: 23
    Speed by Degrees: 1/20
    Speed by Electronic: 1/13

    Setting: 10
    Degrees: 69
    Speed by Degrees: 1/7
    Speed by Electronic: 1/4

    Setting: 5
    Degrees: 139
    Speed by Degrees: 1/3
    Speed by Electronic: 1/3

  7. #17

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    taking some of the Retinas apart can be difficult...

  8. #18
    Bill Burk's Avatar
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    So I had a hunch the exposure method would throw in a wrench...

    1.0 LogE from metered point to speed point (0.10) is for approximately 12% but my target was 18% gray.

    So I shifted my shutter speed estimates 1/2 stop towards being faster speeds.

    And you thought there was no practical use for knowing the trivia about 18% gray cards...

    Also I said the rotational speed was a sanity check. You can see from the photo... There's no denying... at 1/25 the rotation in degrees is extremely clear. Shutter speed is really 1/20.

    I made up a new cheat sheet for the camera where I use Exposure-based high speeds, rotational-based medium speeds, and electronic-based slow speeds.

    As you can see, no one method (as I've implemented) works effectively for all speeds - but the entire set work together well.

    500 = 1/160 (exposure-based)
    250 = 1/100 (exposure-based)
    100 = 1/70 (exposure-based)
    50 = 1/35 (exposure and rotation agree)
    25 = 1/20 (rotation-based)
    10 = 1/7 (rotation-based)
    5 = 1/3 (rotation and electronic agree)
    2 = 3/4 (electronic)
    1 = 1 (electronic)

  9. #19
    Bill Burk's Avatar
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    Quote Originally Posted by Xmas View Post
    taking some of the Retinas apart can be difficult...
    I'm fortunate to be working with a late-model Retina I, and have two of them (thanks momus)... I did not go deep... Just cleaned, lubed and adjusted the easy-to-access shutter parts and made sure the shutter blades were about as free as they could be without disassembly.

    My wife told me I can't get the "index finger as rangefinder" tattoo I wanted. So I'll be using a sharpie.

  10. #20

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    Quote Originally Posted by Bill Burk View Post
    So I had a hunch the exposure method would throw in a wrench...

    1.0 LogE from metered point to speed point (0.10) is for approximately 12% but my target was 18% gray.

    So I shifted my shutter speed estimates 1/2 stop towards being faster speeds.

    And you thought there was no practical use for knowing the trivia about 18% gray cards...

    Also I said the rotational speed was a sanity check. You can see from the photo... There's no denying... at 1/25 the rotation in degrees is extremely clear. Shutter speed is really 1/20.

    I made up a new cheat sheet for the camera where I use Exposure-based high speeds, rotational-based medium speeds, and electronic-based slow speeds.

    As you can see, no one method (as I've implemented) works effectively for all speeds - but the entire set work together well.

    500 = 1/160 (exposure-based)
    250 = 1/100 (exposure-based)
    100 = 1/70 (exposure-based)
    50 = 1/35 (exposure and rotation agree)
    25 = 1/20 (rotation-based)
    10 = 1/7 (rotation-based)
    5 = 1/3 (rotation and electronic agree)
    2 = 3/4 (electronic)
    1 = 1 (electronic)
    As upsetting as it is to accept, Bill Burke's readings are something I can believe. But all my testing has been on an IR diode, robbed from an Apple mouse, and the typical sound-card method. And I've come up with equally dismal results. So I can [sort of] concur. Evidence the shutter is in bad need of CLA. And even then I doubt the speeds could come up to actual marked speeds and stay that way for more than a year. The more I study and work on shutters, the more I believe that accuracy is fleeting. I've also learned that 1/25 is usually about the only one that's anywhere near, by percentage.
    I know Bill is disappointed at these numbers, because I've been there. But I also believe his numbers are the sad truth.

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