I'd like to pick the brains of the Omega experts here and ask about the relative accuracy (in generally accepted terms - obviously this can differ to some extent from watch to watch) of vintage Omega calibres. If I was keen to buy vintage pieces (my interest is mainly in pieces from the 50s and 60s) and accurate time-keeping was one of my main parameters, what calibres should I particularly be on the lookout for?

 

For autos, the 551/552 no-dates, the 564/561 and 565 dates and the 751/752 day + dates are about as good as it gets. For manuals, any of the 600 series. The autos above are the chronometer rated/non-rated versions, but after so many decades that doesn't mean a lot and it's down to the condition of the movement and the effort your watchmaker is prepared to put into servicing and fine adjustment. For instance, I ran my 552 Seamaster de Ville for a month and at the end it was 20 secs out, which is not bad for a 50+ year old movement. Other factors affecting accuracy are how fully wound you keep the watch, either by manually winding it or arm movement; the position you lay it in at rest and overnight; whether you've just started wearing it or have had it on for days; and your lifestyle in general.

If you just want accuracy, 60s Geneves with 552 and 565 movements in good condition will be as good as the 551s and 561/4s in Constellations. If you want more than just accuracy, the case quality and finish is better in Seamasters and Constellations, though a few cases housed both the Geneve and Seamaster lines and the only difference I can see is the wording on the dial. For those models, the magic word "Seamaster" adds £100 or so to the value.

 

as @Edward53 says "a lot and it's down to the condition of the movement and the effort your watchmaker is prepared to put into servicing and fine adjustment"

In my experience this is the biggest factor with older watches and it is amazing how accurate some of them after they have been properly serviced.

 

When you are looking for accuracy, I can’t recommend enough the Cal 30 line. I had two that where holding COSC levels after my watchmaker took care of it. But I wouldn’t care about precision on such old pieces and just enjoy them for their history and design.

 

It really is about the style and history with these watches
Not accuracy
Of mine the 551 and 30t2rg stand out
With the 30t2rg having the edge
But if you are expecting to match quartz
You will find these are not watches for you on a daily basis

 

There are no specific calibers that will predictably be more accurate than others for vintage. It really all comes down to condition, skill of your watchmaker, availability of replacement parts, and lastly (if not most importantly) how much you are willing to spend for accuracy improvements.

Even with lots of money, time, and a good watchmaker, don't expect any miracles...

 

My 1962 Constellation cal 561 was recently serviced.
Runs beautifully, I think within chronometer standard, and perhaps even better than my 2017 Speedmaster Pro.
So, if it's maintained well, it can run within COSC specs 50+ years after it's birth.
And my 1967 Longines Ultra-Chron ran +/- 1-2 sec per day. It was also serviced in ~ 5-year interval.

 

Thanks everyone for your responses, especially @Edward53. All really helpful. I have a recently purchased Seamaster 600 manual wind from 1965 which after a recent service is running at around +3 sec/day. According to my watchmaker, from what he could tell this was probably the first service this watch has ever had so perhaps there's something to be said for a solid, reliable movement in the first instance.