This article is from the WatchTime archive and was originally published in July 2022.
With the Model 158, Sinn has revived a little-known historical German Bundeswehr chronograph. Now presented as a revamped limited edition, how well does this retro chronograph perform?
Sinn is known for making watches for police and military: the EZM 1, for example, was the first mission timer designed by Sinn in 1997 for the German Customs Administration’s special forces. Sinn developed the UX diver’s watch with the German police special forces GSG 9 in mind, which are also worn by members of the German Navy Special Forces Commando, and the 212 KSK meets the requirements of the German Army Special Forces Commando.
However, fewer watch fans may know about Sinn’s past connection with the German Bundeswehr. In the 1980s and early 1990s, the company’s founder Helmut Sinn purchased retired Bundeswehr chronographs (Ref. 1550 SG) made by Heuer that were owned by the German military. Helmut Sinn improved these watches and later sold them as the Sinn model 155 Bw. The dial bears the Sinn inscription: “Heuer/Sinn Bunderswehr-Chronograph für Piloten” (Heuer/Sinn German Pilot’s Chronograph in German).
Now, in tribute to this watch, Sinn releases the test model 158 in a limited edition of 500 pieces. The design of this watch is largely unchanged from its predecessor. Those who know the original model will immediately notice that the new watch is almost identical to the Bundeswehr chronograph, but some details have been changed. The case is almost 100% identical to the original. Faithfulness to the details is evident in the shape of the pushers, the crown without lettering for ease of use, and above all, the bidirectional rotating bezel made of black anodized aluminum, which pays tribute to its predecessor with its minute scale and numeral typography. Even small details such as the grooves of the rotating bezel, the fully drilled strap lugs, and the rather unusual snap-on case with four set screws are family resemblances. The bead-blasted surface of the case, the 43 mm diameter, the opaque metal back, and the domed acrylic crystal also match those of the original 155.
Meanwhile, the dial of the new watch is slightly different from its predecessor. The bicompax arrangement of the subdials (seconds on the left, elapsed minutes on the right) and the typography of the numerals indicating the hours are the same as the original, but some changes have been made. For example, the elapsed time hand of the chronograph is highlighted in red, the hands have a more modern shape, a date display has been added at 6 o’clock, and the original scale with numerals every 5 minutes has been replaced with a scale of split-second markers in 5-minute increments. The new dial looks harmonious and follows Sinn’s characteristic color scheme. Moreover, the updated design has hardly lost the excellent legibility that topped the specification list of the original Bundeswehr chronograph.
Ease of operation was also an important item on the military’s requirement list. As is typical with this caliber, the pushers require a lot of force, especially when starting the chronograph. Operating the stopwatch function is not made any easier by the original shape of the pushers, which only have a fairly small area at the top of their circle. Functionality is improved by the crown, which is low in height but has a large diameter. The crown, like its historical ancestor, protrudes quite far from the side of the case, making this grooved button easy to turn and easy to pull outwards. The stop-second mechanism stops the balance, which also stops the hands. This makes it easy to set the time with a precision to the second. The bidirectional rotating bezel does not click into place at specific increments, but it is still a pleasure to operate. It moves smoothly, but is not so easy to accidentally move out of position.
Robustness was the third most important requirement for the military. At first glance, the operating elements could be a source of potential concern here. Fortunately, on closer inspection, the long push-pieces and the protruding crown sit firmly and without play in their guides, giving the impression of being very robust. The flat bezel does not protrude from the case, so there is little need to worry that this rotating ring will get caught on something and fall off, even without the screw-down, no-lose-it bezel technology so often used by Sinn. The acrylic crystal on the dial is not as scratch-resistant as sapphire crystal, but it is made of the same material as its ancestor and at least will not crack even if it receives a strong impact. The case’s 100-meter water resistance is more than enough for a pilot’s watch.
Despite its high pressure resistance, Sinn has managed to make the watch quite slim. Because the 158 is fitted with an automatic movement which is taller than the original model with a manual caliber, it can’t be quite as slim as its predecessor’s 13mm, but its 15mm height and outwardly sloping bezel give it a reasonably low profile. The curved back and recess in the middle of the case give the chronograph an even slimmer appearance.
Most of the original Heuer/Sinn Bundeswehr chronographs were equipped with the Valjoux hand-wound caliber 230 with column wheel and flyback function. The new 158 employs Sellita’s automatic caliber 510. Critics claim that Sellita is merely imitating ETA movements (copying is not prohibited because the patent protection has expired). This claim may be true in most cases, but with the caliber 510, Sellita has achieved something that ETA has not yet achieved with the Valjoux 7750: a symmetrical dial arrangement (tricompax or bicompax) combined with a fast reset function for the date mechanism via the crown. The ETA Valjoux 7753 requires a corrector at 10 o’clock, which requires an additional opening in the case for this additional button. We prefer Sellita’s more elegant solution.
Apart from this detail, the Sellita movement is comparable to its robust ancestor with a cam switch and a unidirectional effective winding rotor. Its clearly perceptible and audible idling may irritate enthusiasts with sensitive hearing. The power reserve of up to 48 hours is also similar to that accumulated by ETA Valjoux movements. Sinn covers its more superior “premium” quality variants with Glucydur balance, decorative finishes and blued screws. The genuine and therefore opaque case back hides the movement, but there is no need to lament the lack of a transparent case back, as this watch concept and caliber were developed with functionality as a priority.
The German Air Force stipulated that a watch must not deviate from perfect time by more than 10 seconds per day while the chronograph mechanism is running. Our Witschi timekeeping confirmed that the modern 158 kept time with much better accuracy than that. With the stopwatch function turned off, it kept near perfect time, averaging less than one second per day. And with the chronograph mechanism turned on, the deviation of four seconds per day was within the acceptable range. However, according to our rigorous grading method, the deviation of 10 or 12 seconds in multiple positions does not qualify it for a very high rating in this category.
For the German soldiers who wore the original model, the watch was a purely functional tool, a tool watch in its purest form. Fine details of craftsmanship played a subordinate role, provided they did not detract from the durability of the watch. This is of course not the case for watches worn by civilians. It is noteworthy that Sinn paid close attention to the quality of the finishing of the case, dial and hands. The aged leather strap with red decorative stitching blends in well with the overall image as well. Only the simple ready-made buckle with a bent (not milled) pin reminds us that the strap and clasp were items that were expected to wear out and require replacement.
The Sinn 158 is priced at $2,660, which is a fair price considering it was released as a limited edition of 500 pieces. Other Sinn models (such as the 103 St Acrylic on Strap at $1,890) are cheaper options for those who are only interested in functionality. But considering its exciting history and superior design compared to other brands, it’s worth calling out your reserves and putting the Sinn 158 into active service.
specification:
Manufacturer: Sinn Spezialuhren GmbH, Wilhelm-Fay-Strasse 21, 65936 Frankfurt am Main, Germany
Reference number: 158.010
Functions: Central hours and minutes, sub-dial seconds, date display, chronograph with central seconds hand and up to 30-minute elapsed counter
Movement: Sellita 510 “Premium”, automatic, 28,800 vph, 27 jewels, stop-second function, rapid reset function for date display, Incabloc shock absorption, fine adjustment by indexes, Glucydur balance, 48-hour power reserve, diameter = 30 mm, height = 7.9 mm
Case: Stainless steel case, domed acrylic crystal above the dial, screw-down crown, 4 screws securing the snap-on case, stainless steel caseback, pressure resistant to 100m, protected against low pressure
Strap and Closure: Cowhide leather strap with stainless steel pin buckle
Rate results (deviation in seconds per 24 hours with chronograph on/off):
Dial-up +3 / 0
Dial Down +5 / +1
Crown Up -3 / -11
Crown Down +1 / -3
Crown Left +4 / -6
Crown Right -5 / -7
Maximum deviation 10 / 12
Average deviation +0.8 / -4.3
Average Amplitude:
Flat position 292° / 269°
Hanging position 264° / 232°
Dimensions: Diameter = 43 mm, Height = 15.15 mm, Weight = 110 grams
Limited to 500 pieces
Price: $2,660
Score:
Straps and closures (max 10 pieces): Beautiful aged leather straps with red decorative stitching, simple buckles7
Operation (5): The crown is easy to operate and also activates the quick date reset function, but the chronograph start button requires a fair amount of force to activate.
Case (10): The finely crafted case is protected from low pressure and can withstand high pressure up to 10 bar. The acrylic crystal is an authentic retro detail, but is not scratch-proof. 8
Design (15): A very handsome classic 14 with tasteful new color accents
Legibility (5): The time can be read very quickly, day or night, although the elapsed time hands are not luminous, so the contrast is low.
Fit (10): The supple cowhide strap makes this watch very comfortable on your wrist.
Movement (20): Sinn offers top-quality movements with attractive decorative finishes.
A “premium” variation of Sellita’s robust caliber. 13
Speed results (10): The average gains are very small, but the maximum differences between some positions are quite large. If you turn on the chronograph, the timing gets lost in the loss column. 7
Overall Value (15): Good value for the price, and being a limited edition, it is likely to retain its value better. 13
Total: 80 points
