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Thread: Speed Graphic Shutter Checking?

  1. #41
    Jim Graves Jim Graves's Avatar
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    Re: Speed Graphic Shutter Checking?

    Quote Originally Posted by Dan Fromm View Post
    Jim, I agree completely on the first point.

    Y'r second point puzzles me. Why do you think that erratic measured shutter speeds, if that's what your problem has been, are due to an erratic shutter timer instead of an erratic shutter or variations in your measurement procedure? ..............
    Because, after I got such discouraging readings, I took the tested shutters to a professional camera repair shop and had them speed tested. They confirmed both that the slower speed readings were relatively accurate and that the higher speeds had been misread by my testers. Which was exactly what my film tests had indicated.

    The testers I used were of two types ... photo-cell (supposedly measuring the amount of light passed) and sound card (measuring the time between opening and closing of the shutter ... which, of course wouldn't be appropriate for testing an FP shutter.) I even made sure I was using the correct light intensity at the recommended distance if such was listed. All, including the Calumet, were close at low speeds and increasingly off above 1/100.

    I still use one of the photo cell testers because virtually all of my shutters max out at 1/125 or less ... except for a couple of 1/300 Optimos ... which might, on a good day reach 1/150 on the 1/300 setting.

    Since I only have two FP shutters ... a 4x5 Speed Graphic ... and an 8x10 Folmer Graflex ... it makes sense to just do a speed test on each with film ... and those results will apply regardless of the lens I'm using.

    Focal Plane shutter time testing is an interesting subject ... but, as my grandfather used to say ... “It is a long road to a small house.”

  2. #42

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    Re: Speed Graphic Shutter Checking?

    Quote Originally Posted by Jim Galli View Post
    Dan, sometimes people engage a problem for the joy of solving it. I recall one silly person who was devising rediculous solutions for crazy long lenses on a 2X3 format camera? Remember him?
    Mr. Galli, there's a slight difference. The silly person didn't just sit and theorize and raise objections to reasonable suggestions, he built something and tried to use it. But yes, it was an extremely silly person.

  3. #43

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    Re: Speed Graphic Shutter Checking?

    Jim Graves, when I first started to use my Calumet tester with my dud RB Ser. B I got bizarre speed readings. So I went looking for the instructions -- I'd got my tester used without them -- and found that, as usual, I was the problem. The procedure for measuring an FP shutter's speeds isn't quite as simple as I'd thought. And now comes the stupid and insulting question. Do you have the directions, did you follow them?

    They're online here: https://1drv.ms/f/s!AggQfcczvHGNmCOeOp5cLpjG-wGo See p. 2.

    As I understand what the Calumet tester does, it doesn't count photons, it just starts timing when it sees that the shutter has started to open and stops when it sees that the shutter has closed.

  4. #44
    Jim Jones's Avatar
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    Re: Speed Graphic Shutter Checking?

    Quote Originally Posted by Dan Fromm View Post
    . . . As I understand what the Calumet tester does, it doesn't count photons, it just starts timing when it sees that the shutter has started to open and stops when it sees that the shutter has closed.
    The Calumet instructions do seem to make some allowance for shutter inefficiency, and warn against it. It demanded careful reading, more than this old man wants to do. The numbers still don't tell as much about shutter performance as does a light versus time curve on an oscilloscope. The amount of light in almost any tester has to be correctly adjusted for accuracy. The testers that rely on sound instead of light seem far removed from reality.

  5. #45
    Tin Can's Avatar
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    Re: Speed Graphic Shutter Checking?

    Well, my 4th Graflex RB Series B 2x3 just flipped its curtain. I may get this one fixed, it looks like new.

    The 2X3 is much harder to work on as it has peened tapered pins that must come out. The bigger models have an easier path.

    I had a strobe connected, with a DIY BiPin connector as I eagerly watched for a slit of life...

  6. #46
    Jim Graves Jim Graves's Avatar
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    Re: Speed Graphic Shutter Checking?

    Quote Originally Posted by Dan Fromm View Post
    Jim Graves, when I first started to use my Calumet tester with my dud RB Ser. B I got bizarre speed readings. So I went looking for the instructions -- I'd got my tester used without them -- and found that, as usual, I was the problem. The procedure for measuring an FP shutter's speeds isn't quite as simple as I'd thought. And now comes the stupid and insulting question. Do you have the directions, did you follow them? ......
    Nothing stupid or insulting about that question ... it is the obvious one.

    And, yes ... the tester when I got it came with the instructions ... and was the only tester I got that even took the light intensity/distance into consideration ... which seems like an obvious element for testing accuracy ... it was the Calumet tester I was referring to when I mentioned in my original post about ensuring the light intensity was correct.

    I think even Calumet admits in the instructions somewhere that higher speeds pose problems with their measuring system.

    I will admit that I did not continue to refine and try to adjust just to get the system as accurate as possible. After fooling with it for some time, I finally just put a roll back on the 4x5 Speed Graphic and used split frames on the 8x10 Folmer Graflex and shot film ... it was pretty easy to come up with repeatable results. Even had I continued to work with the Calumet, I still would have had to test the results with film anyway ... so I shortened the process ... burned more film maybe ... but ended up saving time and being confident in my results.

    If I had a lot of FP shutters to test ... I would have continued to try to refine my results with the tester ... but with just 2 shutters to test, continuing to test with the Calumet was becoming an academic exercise instead of a practical one.
    Last edited by Jim Graves; 10-Feb-2018 at 22:47.

  7. #47

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    Re: Speed Graphic Shutter Checking?

    Boy you guys just love to overthink things and discuss in circles

    In defense of both Graflex and Calumet I'll toss in my experience. Although it's been many years since I tested my shutters...

    When I first got the Calumet tester, I tried it on a couple of Speed Graphics with impressive results. Well within factory specs, even before cleaning and lubing. I ran into trouble with the leaf shutters as they were all out of spec and slow at the higher speeds.... Exhaustive research provided the answer. You _never_ measure a leaf shutter at the center of the opening! Now as I said up top, it's been years so I don't remember the exact measurement, but you're supposed to measure a leaf shutter approximately one third out from the center. This will give the true speed of the shutter and is how the factories did their tests and calibrations. Yes this is documented. No, I don't remember where any more. Very probably in a Graflex service manual? So for leaf shutters, you must have the light source, shutter and tester in rigidly fixed positions to get accurate results.

    During my tests, I thought about finding our just how accurate the Calumet tester truly was? Best thing I had were several electronically controlled 35mm cameras. Each one of them tested well within specs all the way up to 1/2000. I have no doubts at all that the Calumet tested is reliable at least up to 1/2000 as my results were far too good and repeatable to be coincidence.

    So there's my 2 cents and worth almost that much

  8. #48
    Jim Graves Jim Graves's Avatar
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    Re: Speed Graphic Shutter Checking?

    Quote Originally Posted by RichSBV View Post
    Boy you guys just love to overthink things and discuss in circles

    In defense of both Graflex and Calumet I'll toss in my experience. Although it's been many years since I tested my shutters...

    When I first got the Calumet tester, I tried it on a couple of Speed Graphics with impressive results. Well within factory specs, even before cleaning and lubing. I ran into trouble with the leaf shutters as they were all out of spec and slow at the higher speeds.... Exhaustive research provided the answer. You _never_ measure a leaf shutter at the center of the opening! Now as I said up top, it's been years so I don't remember the exact measurement, but you're supposed to measure a leaf shutter approximately one third out from the center. This will give the true speed of the shutter and is how the factories did their tests and calibrations..........
    That's interesting .... but the Calumet instructions don't agree ... they specifically direct you to “place the probe of the shutter tester at the center of the front or rear lens element” when testing leaf shutters.

  9. #49

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    Re: Speed Graphic Shutter Checking?

    I'm the OP, and I don't take offense at any naysaying that may be in this discussion. So far, IIm still leaning to the method of using a strobe-calibrated home entertainment-grade record turntable from the 80's and some x-ray film already on hand. Certainly there will be some curving of the angle lines in the negative. Just as we all remember the photo of a race car with oval wheels shot on a focal plane shutter 60 or 70 years ago. I don't think Kodachrome 1/4 stop standards are too much to ask. After all, Kodachrome had been around 14 years before my Pacemaker Graphic was made. I bet those Pacemakers came out of the factory with remarkably accurate shutter speeds. And if you want to talk about perfection in standards to the point of ending up in a straitjacket, consider the problems in calibrating the Apollo cameras. The camera was boiling hot when the astronauts were shooting on the bright side of the LEM, and bitterly cold on the other side. Don't you know how THAT played havoc with shutter speed accuracy? Shooting a phonograph record on a reasonably well calibrated turntable might be the best way for regular folks after all. At least you could be happy knowing that 1/1000 was actually closer to 1/650, plus or minus 1/4 stop. I never sought to touch off a discussion that requires large incomes for perfection in trivial pursuits. I'm grateful for what I've read here. Regards.

  10. #50

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    Re: Speed Graphic Shutter Checking?

    Good morning Henry. I’m curious. I’ve seen accuracy specs in shutter repair manuals but never heard of a “Kodakachome 1/4 stop standard”. Is that referring to the narrow exposure range of the film or a real requirement established by Kodak on equipment using that film. What’s the source? Or is it a shorthand term for something like ‘the closest someone thinks they can get a shutter to the ABSOLUTELY EXACT timing values specified on the shutter?

    The reason I ask is you may have an incorrect assumption. Graphex shutter official spec is approx plus/minus 1/3 stop, and my memory recalls even more at speeds above 1/100.

    Scientific cameras are a whole other topic. But when I worked with som for a very brief period of time the focus was on reliability rather than accuracy better than OEM spec.

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