AP Royal Oak Openworked Perpetual Calendar 25829ST

ED209 · 2014-03-15T15:00:58Z

ED209 showcases his Audemars Piguet Royal Oak Openworked Perpetual Calendar 25829ST, detailing its leap year date transition and caliber 2120/2802.

ED209

WPS member · Audemars Piguet forum

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ED209 shares an annual tradition, documenting the leap year date transition of his Audemars Piguet Royal Oak Openworked Perpetual Calendar reference 25829ST. His detailed photo essay captures the intricate dance of the calendar subdials as they advance from February 28th/29th to March 1st, offering a rare glimpse into the mechanical marvel of this complication.

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The Audemars Piguet Royal Oak Openworked Perpetual Calendar 25829ST is still my favorite watch in my small collection. I wear it almost daily and throughout the year I look forward to the end of February for the transition of the date from February 28th or 29th over to March 1st. I've posted the past few years on the performance of my Royal Oak Perpetual Calendar and it has performed well even with the leap year change at midnight. So how did my watch perform this year? Let's take a look.

I just arrived back to Los Angeles from a business trip so I rushed back home to set up a small space to photograph my Royal Oak. My first pictures started a few minutes past 8pm and you can see that the date subdial at the 3 o'clock position has already started moving from the 28th over to near the 29th day. In my prior experience most of the subdials do most of the calendar movement within 10 minutes counting down to midnight.

During breaks in between taking pictures I always turn the Royal Oak around to view the skeletonized caseback. Audemars Piguet uses the caliber 2120/2802 which is merely 4mm thin and 28mm in diameter. Light scroll work engraving adds an elegant touch to the bridges, plates and rotors. I've owned this Royal Oak Perpetual Calendar for several years and it's been extremely reliable movement. I must admit that every once in a while I think about getting a custom engraved rotor, but I think that AP did a great job with the style of the skeletonized rotor.

At 9 o'clock not much has changed, other than the date subdial which has go all the way from the 28th to the 1st. So you can see that a few minutes past 9 o'clock it has already moved over to the 29th.

At 10 o'clock, I can see continuous movement of the date as it gets to the 30th. All other subdials are in the same position. One observation I noticed while looking over my pictures compared to last year is that the moon phase was showing mostly stars and a dark night, as compared to last year where it was nearly a full moon.

At 11 o'clock, the date subdial is near the 31st while the day is staring to transition from Friday to Saturday.

Fast forward to 11:44pm and more subdial movement. The date is inching closer to Saturday and the date is past the 31st.

And just like in previous years a lot more happens within ten minutes to midnight.

In under two minutes to midnight, we get closer to a date displaying the 1st and day getting closer to Saturday. The month is still at February.

A few seconds before midnight and the AP is displaying Saturday the 1st, but month hasn't changed yet. I like having the Royal Oak on my wrist to watch the transition.

Upon closer inspection, I see that a minute after midnight and the month is still displaying February.

I wait a few more minutes and the same thing.

I wasn't too worried and waiting a few more minutes and somewhere between 5 and 10 minutes past midnight the month subdial transitioned to display march.

Overall I'm happy with the performance of my Audemar Piguet Royal Oak Perpetual Calendar. I can't wait again till next year to see it all again. I've actually been making a few trips to the local AD to look at the Royal Oak Equation of Time, but it's a little bit large at 42mm in diameter. I think for now I'll continue to enjoy my 25829, I love the 39mm case size as the proportions of the watch are perfect on my wrist.

Regards,
ED-209

This message has been edited by ED209 on 2014-03-15 15:04:33

Key Points from the Discussion

The small hand in the month subdial at 12 o'clock on the Audemars Piguet Royal Oak Openworked Perpetual Calendar indicates the current year within the leap year cycle.
The caliber 2120/2802, at only 4mm thin and 28mm in diameter, is praised for its reliability and elegant scroll work engraving on bridges, plates, and rotors.
Many collectors are fascinated by the idea of custom-engraved rotors for high-end AP watches, considering options like family initials or unique personal symbols.
The 39mm size of the Royal Oak is considered perfect by many, including owners of the 39mm Royal Oak Chronograph.
The steel version of the Royal Oak Perpetual Calendar is surprisingly lightweight compared to older yellow gold models with solid dials and casebacks.
The experience of watching the date transition on a perpetual calendar, especially during a leap year, is a highlight for owners, adding to the appreciation of the complication.

The Discussion

amanico

Mar 15, 2014

A fantastic perpetual calendar, one of my favourite, and they are not that many! [nt]

ED209

Mar 15, 2014

I know of your fondness for this AP

Thanks Nicolas! Regards, ED-209

emijar3

Mar 15, 2014

Great report ED!

Didn't know that the perpetual calentar had that feature!! Good to know!! Best! Ernesto