13ZN Chronographs Inquiries and Information.

DirtyDozen12 · Mar 15, 2019

@foil_guy Here is a link to a post that indirectly addresses the issue above: https://omegaforums.net/threads/pretty-movements-anyone.35781/page-2#post-405812

foil_guy · Mar 15, 2019

thanks, in essence like a single pusher hanhart. As opposed to the chronostop that omega produced.

DirtyDozen12 · Mar 15, 2019

F foil_guy
thanks, in essence like a single pusher hanhart. As opposed to the chronostop that omega produced.

Yes. Longines also produced "chronostop" or stop-seconds movements: https://omegaforums.net/threads/tho...reviously-sold-at-hodinkee.68157/#post-855439

Lépine · Mar 16, 2019

DirtyDozen12
"Monopusher" and "flyback" are mutually exclusive.

On a 13zn that is true. However, monopusher flyback do exist. I have one.

I believe there are at least two Longines Chronograph movements that can do this.

PHPHD · Mar 16, 2019

Seiji
On a 13zn that is true. However, monopusher flyback do exist. I have one.

I believe there are at least two Longines Chronograph movements that can do this.

Is that different from a chronostop (i.e the chronograph continuously runs, and the button resets)?

foil_guy · Mar 16, 2019

Sorry if a slight tangent, here is a Ref 3795 next to the 13Zn Ref 3721. Interesting for size and style comparisons, of military format pilot watches of the era.. Another original but wabii'd dial. This one is an issued piece, with the F5357

Lépine · Mar 16, 2019

PHPHD
Is that different from a chronostop (i.e the chronograph continuously runs, and the button resets)?

Absolutely, 12.68Z and 18.72 chronostops. But, does not diminish DD12 main point that 13zn mono do not flyback.

DirtyDozen12 · Mar 17, 2019

Seiji
On a 13zn that is true. However, monopusher flyback do exist. I have one.

I believe there are at least two Longines Chronograph movements that can do this.

I do not know the history of the words "monopusher" or "flyback", as they pertain to watch movements. But in my view, they are terms that denote an unconventional design when compared to the normal, two-pusher chronograph. Under this, admittedly, arbitrary assumption, it would not make sense to apply these terms to Longines' stop-seconds movements. I suspect that my motivation to operate under this assumption is that doing the contrary would undermine the functionality of movements like the 13.33Z, 13ZN, and 30CH.

Lépine · Mar 17, 2019

DirtyDozen12
I do not know the history of the words "monopusher" or "flyback", as they pertain to watch movements. But in my view, they are terms that denote an unconventional design when compared to the normal, two-pusher chronograph. Under this, admittedly, arbitrary assumption, it would not make sense to apply these terms to Longines' stop-seconds movements. I suspect that my motivation to operate under this assumption is that doing the contrary would undermine the functionality of movements like the 13.33Z, 13ZN, and 30CH.

I don't see a problem with calling them true Chronographs and a flyback. They have accumulation registers so it is possible to time a full leg. It resets and restarts a new leg instantly like a flyback is supposed to. Everything you can do with a 13zn flyback you can measure with a chronostop. From a timing standpoint, these were used by the US Navy for ship maneuvers. They were also used by the Scandinavian Navies. They are not gimmicks. The single button simplified operations and avoided button confusion.

Update: Some Flyback Chronostop pocket watches were ordered by the Bulgarian Royal Army.

DirtyDozen12 · Mar 18, 2019

Seiji
Everything you can do with a 13zn flyback you can measure with a chronostop.

In order to stop the chrono hands of a stop-second movement, constant pressure must be applied to the pusher. This means that one of the wearer's hands is occupied while the chrono is stopped. Furthermore, in order for the chrono to be stopped and not reset, a specific pressure must be applied to the pusher. This could be difficult to execute while wearing gloves, for example. Additionally, when the chrono has been stopped but not reset, the chrono second hand is prone to accidental movement due to the absence of a blocking lever or similar components.

The limitations outlined above are a consequence of the simplified design. And while stop-second movements are capable of being reset while running, they lack basic functionality that is indicative of traditional, flyback chronographs like the 13ZN or 30CH.

Lépine · Mar 18, 2019

DirtyDozen12
In order to stop the chrono hands of a stop-second movement, constant pressure must be applied to the pusher. This means that one of the wearer's hands is occupied while the chrono is stopped. Furthermore, in order for the chrono to be stopped and not reset, a specific pressure must be applied to the pusher. This could be difficult to execute while wearing gloves, for example. Additionally, when the chrono has been stopped but not reset, the chrono second hand is prone to accidental movement due to the absence of a blocking lever or similar components.

The limitations outlined above are a consequence of the simplified design. And while stop-second movements are capable of being reset while running, they lack basic functionality that is indicative of traditional, flyback chronographs like the 13ZN or 30CH.

To summarize: They do operate differently and each has different advantages and compromises. For military use, the chronostop watch variations were chosen as well as standard chronographs implying that chronostop flyback movements met all functional requirements. A monopusher chronograph movement can be made to flyback.

Lépine · Mar 25, 2019

If anyone isn't familiar, this is a flyback military Chronostop made for many Airforces, Canadian Royal Airforce, Japanese Imperial Army, Israeli Defense Force, etc. 12.68z flyback monopusher.

View attachment 732462

Lépine · Mar 26, 2019

Interesting 13zn. 34mm steel case with tapered bezel. It was completely authenticated with a right subdial misaligned. It is too high and too far to the right. This is a counter-sunk dial.