# Hummers And Chronometers



## handlehall (Aug 7, 2009)

Bought this accutron from Ebay this week (apologies for rubbish photography)so far very pleased with it, condition - wise the dial has 1 or 2 odd blemishes but not really noticeable in daily use; humming away strongly and keeping good time. I also have the Omega Seamaster f300 which thanks to the skills of Silver Hawk is now performing as intended. When comparing the 2 watches it occurred to me that according to what I have read this type of watch used similar types of ESA movement. So considering the Omega is rated as a chronometer, should I expect the same accuracy from the Bulova? Are the movements only superficially similar? Also, considering the accuracy of quartz has that really made the chronometer tag obsolete? presumably testing etc. by COSC is/was costly


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## Filterlab (Nov 13, 2008)

handlehall said:


> I also have the Omega Seamaster f300 which thanks to the skills of Silver Hawk is now performing as intended. When comparing the 2 watches it occurred to me that according to what I have read this type of watch used similar types of ESA movement. So considering the Omega is rated as a chronometer, should I expect the same accuracy from the Bulova? Are the movements only superficially similar? Also, considering the accuracy of quartz has that really made the chronometer tag obsolete? presumably testing etc. by COSC is/was costly


The Omega movements were considered the 'Rolls Royce' of hummers, and the slightly different arrangement of the mounting position of the tuning fork assembly (i.e. centrally rather than at one end) made for a much improved timekeeping. Even though the Cal.1250 was essentially an ESA 9162, the difference in this layout of the fork meant that it was more accurate as positionally it was unaffected for all intents and purposes. The F300 movements were consequently COSC tested and rated and even now they keep way better time than most mechanical watches. Yes, quartz really is very accurate indeed (if undertaken properly) but not much more accurate than a well set up tuning fork or mechanical watch (if you discount the Omega Marine Chronometer of course).

As for the difference between your Bulova and Omega, I don't think they'll be a lot it in provided the Bulova is stored dial up rather than crown up/down, but then again the Omega isn't rated to Chronometer standards for nothing! Mine's 36 years old and runs at +1.5 seconds per day. Saying that my 1975 Seamaster Mariner runs at.... well, +/-<0.5 seconds per day if I'm honest.


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## Filterlab (Nov 13, 2008)

Have a look at the Seamaster F300 120m page on Desk Divers, there's a good slab of info about the Cal.1250 movement on there.


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## handlehall (Aug 7, 2009)

Thanks for the informative response, as a matter of interest what method do you use to assess the accuracy of your watches? for instance is the best reference the Greenwich time signal and is it best to average out over a few days? presumably it's only a meaningful measure when the watch is being worn. Sorry if I'm being a bit simple here but sometimes the obvious isn't always the right way!


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## watchking1 (Nov 14, 2007)

My OMC has been off less then 1 second in the past six months :cheers:


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## Filterlab (Nov 13, 2008)

handlehall said:


> for instance is the best reference the Greenwich time signal and is it best to average out over a few days? presumably it's only a meaningful measure when the watch is being worn.


Yep, yep and nope.

I set any watch I want to assess with the Greenwich signal (or on the GMT website) and then I use it and wear it as normal. I check it after a few days and then average the results out.

It's a meaningful measurement whether the watch is being worn or not as the position the watch is stored in overnight can affect timekeeping, although with the ESA 9162 based movements, the mounting position of the fork reduces the potential for positional inaccuracies from two positions to a theoretical zero (a mechanical Chronometer standard movement is tested in five positions for inaccuracies). An electronic watch should be theoretically less prone to positional variation than a mechanical, but as always there are exceptions to any rule - Omega's coaxial movement for example.

All in all a hummer should be very accurate, even if it doesn't have a Chronometer certificate.


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## handlehall (Aug 7, 2009)

Didn't think to google GMT :wallbash: have just set the Accutron so will assess it over the next few days out of interest - thanks again for your input Rob, the deskdivers article was very interesting too.


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## Filterlab (Nov 13, 2008)

handlehall said:


> Didn't think to google GMT :wallbash: have just set the Accutron so will assess it over the next few days out of interest - thanks again for your input Rob, the deskdivers article was very interesting too.


My pleasure mate. That Desk Divers article is absolutely excellent, by the time I'd finished reading it I couldn't wait to get an F300!


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