Chronograph increment specifications...

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  1. #1
    Pil-Mil, Breitling Forum Moderator O2AFAC67's Avatar
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    Exclamation Chronograph increment specifications...

    I stand corrected. And so does every Swiss watch manufacturer who spec'ed their chronographs at 1/5 or 1/4 second. Breitling has done both over the years and continues to do so. Obviously, 3 small tick marks between a second/minute marker divide the space into four equal parts (1/4 second chrono) and 4 small tick marks divide the space into five equal parts (1/5th second chrono). In fact, a 28,800 VPH movement (7750's, 2892's) moves the sweep chrono second hand forward eight times in a second. A 21,600 VPH movement (1873-77 Lemania) moves the sweep chrono second hand forward six times in a second. Tough for the human eye to discern the difference in either rate or spacing which dictates a specification that is seemingly apparent to the viewer when the chrono hand is stopped. (Hand width issue if nothing else.) Hope this makes sense for you. I proved the incrementation totals yesterday using a video camera with a frame time slowed to 1/4th real time in order to actually be able to see and count the "ticks" of the hand between second markers. Viewing the movement on the monitor at the reduced rate shows the number of movements ("ticks") precisely. Now the longstanding chrono incrementation issue is put to rest...

    Following paragraph xcerpted from a Timezone.com archive...
    Obviously, the gear ratios of the time train are designed for the movement to display the time in increments relative to the balance rate. Independent of this, the gear ratios of the chrono train are designed to move the chrono sweep at the desired rate. This is all part of the design of the movement. Given the amount of space available and the number of teeth that can accurately be cut on a wheel of a certain diameter, the limitations of the chrono rate fall into a range that can be chosen for the chrono sweep. One could begin with a clean sheet of paper and design a movement that could run at 28,800 and sweep in 1/5 second steps on the chrono...

    Those facts plus the manufacturor specifications (Chronologs) are the data which leads one to determine incrementation specificity, although my real-time test proves those specifications as false. That said, justification for 1/5 or 1/4 second incrementation markings is easily realized. Historically, 1/5 second timing has been (still is) applied to horse racing since the 19th century. Stopwatches for trainers and enthusiasts purchased today are marked 1/5 second increments. For a 21,600 VPH wristwatch chronograph (Lemania Cossie, Omega Speedmaster), the difference between 1/5th spacing or 1/6th spacing are simply not discernible to the naked eye. That assertion is also true for the 28,800 VPH movements marked in 1/4th second increments. As stated earlier, the width of the sweep second hand is greater than the difference between 1/8th second and 1/4 second. The manufacturor specifications then become misleading we might say, but aesthetics, practicality, manufacturing limitations, mechanical start/stop variances, human "reaction" limitations, and lastly our vision are the real reasons for more or less "standardization" of wristwatch chronograph incrementation markings.

    Want to know what got me started on this crusade? (Besides having read many articles on movement and chronograph operation... ) It was Breitling Chronolog specifications for the chronograph pieces. I happened to notice that the increment markings on my 2001 Crosswind (discontinued after 2004) concurred with the 1/5th second specification in not only the Chronolog but also the 2004-2005 sales handbook. However, there were two dial "styles" available for the CW, the one like mine with "slanted" arabics in the subdials and the other with "straight" arabics in the subs. The latter was marked for 1/4 second incrementation! Ooops! Why the disparity? I went back through all the Chronologs and found the same issue for the CW. Slanted subs=1/5th sec., straight subs=1/4th second markings. Hmmmmmmm... Next I checked specs on my 21,600VPH Lemania Cossie and my caliber 22 Flyback Cossie (2892-A2 movement, 28,800 VPH) and found both marked on the dials for 1/5th second and indeed spec'ed that way in the Chronologs and Sales Handbooks. Something wasn't adding up. I began to research chronograph operation relentlessly and was never able to find an adequate explanation for the disparity in markings. Detailed study of the movements led me to incorrectly conclude it had to be gearing ratios in the chrono train and nothing else. Still, it seemed as though the "dirty little secret" would not be revealed with research and conclusions alone. A controlled "test" was the only way to prove with finality what many of us suspected or denied. That is the reason I set up the camera and software and used four of my Breitlings as test subjects. Fortunately I have available all examples of the calibers and markings necessary to make the test conclusive and accurate. A little embarrasing for me to have to "stand corrected" from false early conclusions but lacking "finality" was nagging at me hence the decision to set up the test. Glad I did it and I hope it helps those of us who are truly intrigued by what many would consider to be trivial and unimportant.
    Best,
    Ron
    Last edited by O2AFAC67; September 16th, 2015 at 11:46.
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  2. #2
    Pil-Mil, Breitling Forum Moderator O2AFAC67's Avatar
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    Re: Chronograph increment specifications...

    Just a quick FYI. Check out the ticking stopwatch at the beginnng of the CBS television news show "60 Minutes". You'll note it is divided into and running in 1/5th second increments... (Horse racing. Remember?)
    Best,
    Ron
    Last edited by O2AFAC67; April 6th, 2014 at 04:35.
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    Off Topic post Re: Chronograph increment specifications...

    While perusing the archives I noticed the 1/5th second increment marks on my long gone 1994-95 vintage Old Navitimer II with a caliber B13 (V7750) 28,800 vph movement. Love it. Of course it's a 1/4th second chronograph movement. A perfect illustration and another example of unintended (?) misdirection by the manufacturer back in the mid 90's...
    Best,
    Ron





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    Off Topic post Re: Chronograph increment specifications...

    To further illustrate the markings disparity...









    I had the B510 dial on my recently acquired (February 2015) pre-loved Crosswind replaced with the B703 version last month during a service visit for two reasons. First, the lume had "died" on the original B510 dial which I understand is a rare circumstance and second, I wanted the correct 1/4 second chronograph incrementation markings for the 28,800 VPH caliber B13 V7750. Interesting to note that after this original "article" appeared in 2009 Breitling quite discreetly dropped any reference to "1/5 second chronograph" specifications in its literature and no longer were the four tick marks seen inside any second markings on any dial in their model lineup..
    Best,
    Ron
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