DATOGRAPH UP/DOWN “Lumen“

The DATOGRAPH UP/DOWN “Lumen” is the fourth model of the “Lumen” series that A. Lange & Söhne launched in 2010. Its semi-transparent dial and luminous coatings assure that all features can also be used in the dark: the time indication, the outsize date, the chronograph functions and the power-reserve indicator. The flyback chronograph with the precisely jumping minute counter comes in a limited edition of 200 watches in platinum. The three most prominent elements of its balanced face – the characteristic outsize date and the two subsidiary dials – form an equilateral triangle. At night, the luminous elements turn the distinctive design into an iconic beacon.

Even in the dark, the displays are clearly legible because the three central hands as well as the applied arrow marker of the power-reserve indicator are coated with a luminous compound. The seconds and minute-counter hands in blued steel each revolve in front of a phosphorescent subsidiary dial. The display surfaces of the outsize date also glow with a green hue perceived as pleasant by the human eye. For the first time in a Lange watch, the inner dial ring with the minute scale is luminous as well.

The clearly configured semitransparent dial of the DATOGRAPH UP/DOWN “Lumen” allows a view of the sophisticated technology that controls the outsize date. Handcrafted details like the perlage on the entire surface of the main plate or the sunburst decoration on the date bridge can be clearly recognised.

The most astounding effect of the lavishly finished manually wound calibre L951.7 is its incredible depth. Indeed, the chronograph movements of A. Lange & Söhne have often been likened to architectural works of art.

The sapphire-crystal caseback allows the most interesting switching sequences to be observed. It exposes the column wheel that controls the stop functions, the flyback mechanism and the minute-counter lever for the precisely jumping minute counter.

A patented construction advances the minute-counter hand of the 30-minute totaliser by exactly one graduation every 60 seconds, even if the time measurement happens to be stopped during the zero passage. This guarantees a precise minute-counter reading at all times.

Lange’s proprietary cam-poised balance wheel, paired with a freely oscillating Lange hairspring, beats at a frequency of 18,000 semi-oscillations per hour. In combination with the 300-marker minute scale, this allows time measurements with a resolution of one-fifth of a second.

“Lumen” is the name of a series of four timepieces that make a vibrant design statement with the help of the newest scientific knowledge. The first was the ZEITWERK “Luminous” launched in 2010 followed by the GRAND LANGE 1 “Lumen” and the GRAND LANGE 1 MOON PHASE “Lumen” presented in 2013 and 2016, respectively. All models were limited platinum editions and soon turned out to be coveted collectors’ items.

The technical challenge encountered in the development of the “Lumen” models was to charge the luminous elements, including those hidden beneath the dial, with light energy. The solution is a sapphire-crystal dial coated with a semi-transparent compound that is permeable to ultraviolet light.

The transmission of light waves in the visible spectrum was attenuated to achieve a high-contrast, perfectly legible dial. On the other hand, light waves in the UV range can pass through. This allows the dials of the “Lumen” models to glow in the dark for several hours.