For more than a decade, A. Lange & Söhne’s Datograph was considered by many to be the quintessential chronograph. On the one hand, it was because of its technical features, on the other because of the unparalleled harmony of its dial. With a number of enhancements, Lange’s engineers are now proving that excellence can be taken a step further. With a power reserve extended to 60 hours, a power-reserve indicator, and a proprietary oscillation system, the new Datograph Up/Down shines in a platinum case enlarged to a diameter of 41 millimeters.

When it was first presented in 1999, the A. Lange & Söhne Datograph already attracted global attention. With its sophisticated technology and subtly balanced design, it clearly stood out from the masses of timepieces with stopwatch functions. The classic column-wheel calibre with a precisely jumping minute counter and flyback function united the cardinal virtues of an exemplary chronograph in a movement of peerless mechanical eloquence and aesthetic appeal. These internal assets were complemented on the outside by the harmony of the dial ensemble: forming an equilateral triangle, the Lange outsize date and the two bright subsidiary dials for the seconds and the minute counter contrasted well against the black dial, assuring superb legibility.

The new Datograph Up/Down embodies all these features as well. Additionally, Lange’s engineers and product designers worked intensely to refine it further. What meets the eye first is the larger case. With a diameter increased to 41 millimetres, this timepiece gains extra prominence on the wrist. Rhodiumed gold baton hour markers on the dial – they also replace the former Roman numerals II, VI, and X – emphasize its clear design and identify the watch as a member of the Saxonia family that was just revised last year. A small detail is typical of the perfectionism pursued at Lange: The aperture of the date display was adjusted to match the bigger size of the case. It was enlarged by four percent to preserve the balanced proportions of the dial architecture.

The designation “Up/Down” in its name refers to an additional function: A power-reserve indicator at 6 o’clock reliably tells the owner how much of the extended 60-hour running time remains available. Only when the hand enters the red zone on the third day will it be necessary to supply the calibre L951.6 movement with fresh energy. The 24 extra power-reserve hours versus the previous model were achieved mainly with a larger mainspring barrel.
The large balance developed by Lange and crafted in-house has six eccentric poising weights that can be very precisely adjusted to fine-tune its rate accuracy. It is powered by a balance spring, also developed and crafted on site by Lange. To assure optimised rate values at its classical frequency of 18,000 semi-oscillations per hour, the spring is scrupulously matched to the characteristic of the movement.

Among many other technical refinements, the Datograph Up/Down features the comfortable but technically complex flyback function found only in very few chrono- graphs. Originating from the early days of aviation, this mechanism makes it possible to perform instantly consecutive time measurements by combining three steps – stop, reset, restart – into one: One single push of a button will stop and reset the Datograph Up/Down in the middle of an ongoing time measurement. When the button is released, a new time measurement is initiated immediately.

The sapphire-crystal caseback reveals one of the technically most immaculate and also most beautiful chronograph movements ever made. It allows the owner to observe the most interesting of the many mechanical processes and artisanal subtleties. Highlights include the precisely jumping minute counter that guarantees exact time measurement, the column wheel that controls the chronograph functions, and the whiplash-spring-secured precision beat adjustment system on the hand-engraved balance cock. All surfaces are meticulously finished by hand. Four screwed gold chatons visually accentuate the micromechanical artistry of this opus. Thus, the apotheosis of time measurement presents itself anew at the state of the art.

Movement	:	Lange manufacture calibre L951.6, manually wound, crafted to the most exacting Lange quality standards, decorated and assembled by hand; precision-adjusted in five positions; plates and bridges made of untreated German silver; balance cock engraved by hand
Movement parts	:	451
Jewels	:	46
Screwed gold chatons	:	4
Escapement	:	Lever escapement
Oscillation system	:	Shock-resistant balance with eccentric poising weights; superior-quality balance spring manufactured in-house, frequency 18,000 semi-oscillations per hour, precision beat adjustment system with lateral setscrew and whiplash spring
Power reserve	:	60 hours when fully wound
Functions	:	Time indicated in hours, minutes, and subsidiary seconds with stop seconds; flyback chronograph with precisely jumping; power-reserve indicator; outsize date
Operating elements	:	Crown for winding the watch and setting the time, two pushers for operating the chronograph, one pusher for rapid correction of the outsize date
Case dimensions	:	Diameter: 41.0 millimetres; height: 13.1 millimetres
Movement dimensions	:	Diameter: 30.6 millimetres; height: 7.9 millimetres
Crystal and back	:	Sapphire crystal (hardness 9)
Case	:	Platinum
Dial	:	Solid silver, black
Hands	:	Rhodiumed gold, steel
Strap	:	Hand-stitched crocodile strap, blue-grey
Buckle	:	Lange prong buckle in platinum