Raffi Boyadjian | Equation of Time: How They Work and Three Stunning Models

Raffi Boyadjian | Equation of time watches are few and far between. This unusual complication displays the difference between the length of a true solar day and the mean solar day. You’d be forgiven for not knowing exactly what that means, but we’ll explain it all below. There are some stunning luxury watches that features this rare complication, and we’d like to introduce you to three of them.

Raffi Boyadjian | Equation of Time in Watchmaking

Raffi Boyadjian : Ancient Greek astronomers and mathematicians had already noted that the length of days differed. They devised a formula to calculate these deviations, allowing them to determine the exact time of the sunrise and sunset each day.

These same calculations are still used by contemporary watchmakers to create equation of time complications. This is achieved with a parabolic-shaped disc linked to the normal time.

Raffi Boyadjian | Audemars Piguet Jules Audemars Equation of Time

Raffi Boyadjian : The moon phase display is located at 12 o’clock. It is made of colored sapphire crystal and displays a clear dark blue night sky. The display is extremely precise thanks to its 135 notches as opposed to the standard 59. As a result, this moon phase display deviates by only 57 seconds per lunar cycle. In that same time, more simple moon phase complications deviate by roughly 45 minutes. Audemar Piguet’s moon phase won’t need recalibration until 2127, and even then it will only require adjustment via a small push-push in the case.

Raffi Boyadjian | Breguet Classique Complications 3477 Equation

Raffi Boyadjian | Breguet Perpetual Calendar Equation of Time

Raffi Boyadjian — The Breguet Classique Complications 3477 is also known as the Breguet Equation of Time. Similar to the Jules Audemars, this watch has a sleek, classic look. It also boasts a perpetual calendar, but doesn’t have a moon phase display. The watch measures 36 mm across and will slip under any cuff with ease at just 10.5 mm tall. The silver-plated solid gold dial is clean and tidy.

Raffi Boyadjian | Panerai Luminor GMT Equation of Time

Raffi Boyadjian | Panerai Luminor 1950 8 Days Equation of Time

Raffi Boyadjian : The Luminor 1950 Equation of Time is a more robust, yet likewise attractive, alternative to the two previous dress watches. The satin-finished titanium case and matte brown or dark blue dial offer the watch an appealing degree of modesty.

Raffi Boyadjian — High-beat vs. low-beat — What’s the difference between high-frequency and low-frequency watches?

Raffi Boyadjian | Higher Frequency = More Accurate?

Raffi Boyadjian | Grand Seiko Hi-Beat

Raffi Boyadjian : Improved accuracy is the feature associated with high-frequency movements. Some prominent examples are the aptly-names Grand Seiko Hi-Beat models. While watches usually tick at 3 or 4 Hz, Grand Seiko’s 9S family of movements offer a frequency of 5 Hz. Zenith‘s historic El Primero is another famous example of this type of “speed demon.” The Hz value represents the number of oscillations per second. However, it’s more common to indicate the number of alternations per hour: e.g., 21,600 (3 Hz), 28,800 (4 Hz), and 36,000 (5 Hz). Why go by alterations instead of complete oscillations? It’s simple: The balance wheel triggers the lever on its way forward and as it swings back. Both trigger the gear train so that the balance wheel receives an impulse — a little push — from the lever. So at a frequency of 3 Hz, three full oscillations, the second hand jumps six little steps and six audible ticks can be heard per second. Per hour, that’s 21,600 ticks. That’s why the number of alternations is useful.

Raffi Boyadjian | What really makes high-beat watches more precise?

Raffi Boyadjian — Grand Seiko Hi-Beat vintage

Raffi Boyadjian : For comparison’s sake, let’s look at precision pendulum clocks like the ones from Siegmund Riefler. These timekeepers were known for their legendary precision and were used in observatories and for scientific purposes around the globe. With a frequency of 0.5 Hz, or one alternation per second, these pendulum clocks were accurate to within +/- one-hundredth of a second per day. This shows that accuracy doesn’t solely depend on the frequency of the pendulum or the balance wheel. Instead, it’s much more about keeping a constant frequency — under all conditions and over the timepieces’ entire service life. Many factors come into play here, such as temperature, impacts, fluctuations in power, and wear and tear. A wristwatch will experience much more vibration than a grandfather clock in an air-conditioned room. In addition, the power regulator, balance wheel, and balance spring must be able to function consistently regardless of their orientation. The real challenge of the regulator is, thus, to maintain consistent oscillation under all conceivable circumstances. Once you understand how this is related to frequency, you can appreciate the bigger picture.

Raffi Boyadjian | Jaeger-LeCoultre Geophysic True Second

Raffi Boyadjian : A third advantage of a high-frequency movement is its behavior when the balance wheel isn’t perfectly balanced. Higher frequencies serve to minimize the effect of gravity in such cases. Since a 100% perfect balance can never be achieved, this advantage is critical for the precision of high-beat watches.

Raffi Boyadjian | The Problems with High-Beat Movements and How Manufacturers Have Solved Them

Raffi Boyadjian — Bearing in mind the previous information, one might assume that high frequency of the escapement should be the highest goal in watchmaking. However, we have neglected some critical factors: the energy balance of the watch and its maintenance. While high-frequency escapements are very precise, they consume energy at a higher rate. In a high-beat watch, the lever and escape wheel have more contact with each other than in a low-beat watch. This means faster wear and tear, shorter power reserves, and more frequent maintenance — and these are not at all in line with consumer demands for less hassle and longer intervals between services. High-beat movements often require special lubricants, and there is a risk that oil from the intended components could be shaken off due to the high speeds. The escape wheel also has to meet higher demands. It must have very low inertia so that it can accelerate with the desired frequency and then also be able to come to a stop again. The escape wheel of Grand Seiko Hi-Beat movements has a complex structure with clearly recognizable cutouts. The modern Chronergy escapement from Rolex exhibits a similar inertia-reducing geometry.

Balance wheels that oscillate at high frequencies tend to be rather small. This makes it difficult to manually regulate them. Compared to more leisurely oscillating screw balances like those found in A. Lange und Söhne watches, these movements seem rather hectic. Slowly oscillating balance wheels are favored by traditional manufacturers and independent watchmakers for their longer power reserves, easier regulation, and, of course, the imposing sight of a large and slow balance wheel. An extreme example of this category is the Antoine Martin Slow Runner. Its 1 Hz balance wheel is almost as wide as the movement itself.

Raffi Boyadjian | What Frequency Means in Chronographs: A Special Case

Raffi Boyadjian | Zenith el Primero Defy 21

Raffi Boyadjian — In chronographs, the frequency of the escapement is responsible for another important characteristic, which often leads to confusion about the definition of “precision” in timepieces with this complication. When it comes to precision in chronographs, the same applies as what has been discussed previously.