What is a chronograph watch and how its special dials work?

Today we are going to talk about some of the most frequently asked questions in the world of watches. What is a chronograph watch and how its dials work and what are they for? And how can I read them?

If you have a watch with 2-3 subdials on the dial and one or more buttons sticking out of the case, you might think you are wearing a special watch. In fact you are wearing a chronograph.

“Chronograph” is the GRE word for timer. A chronograph can be used as a stopwatch without affecting the clock’s timekeeping, and can be used for various time periods (such as 1 minute, 1 hour, or 1 day – more on that later).

Chronograph Watch

How Chronograph watch works?

In watchmaking terms, chronographs fall under the term complication (a watch that performs multiple functions).

Common complications are date displays, alarms and, of course, chronographs displaying various time intervals.

Luxury watches can be decorated with moon phases and other intricacies.

Taken together, the seconds hand and subdials are the horological complication that performs the stopwatch function that gives the chronograph its name.

Some of the most famous chronographs in the modern world of watchmaking are the Rolex Daytona, Omega Speedmaster, or Zenith El Primero.

Chronographs are a perennial favorite among collectors, and especially in recent years, they are experiencing an unprecedented boom in the collector community.

Chronograph Explained in Diagram

What is a chronograph watch and its dials explained

Let’s start by describing the elements found in this type of watch dial.

Functions of Key Watch Parts

A. Date Window

The date window, usually located at 3 o’clock or between 4 and 5 o’clock or at 6 o’clock, indicates which day of the month it is. The date at 3 o’clock is arguably the most common date position in the history of the date window on the dial. It was popularized by Rolex’s 1945 Datejust and has been a timeless design ever since.

This date window is often associated with a cyclops lens designed nine years after its release because the wife of Hans Wilsdorf (the founder of Rolex) couldn’t read the date without glasses.

B. Second Hand Subdial

The second hand subdial is also known as fractional seconds. Normally, the second hand of high-end chronometer watches stops and does not move. Instead, the seconds function appears on one of the smaller dials, usually numbered 20-40-60.

This subdial is also found on many non-chronograph watches and is a purely aesthetic choice.

C. So why do we need a second hand?

On chronograph watches, pressing the top button on the crown (D.) at 2 o’clock starts the second hand and can be used as a chronometer.
At this point, you’re enjoying this wonderful feature of your watch, but you might have a question: How do you know how many minutes or hours have passed since you started the chronometer? Next, we need the remaining two of the three smaller dials.

E. The Minute Subdial

Activate the chronometer to see the elapsed minutes. It often achieve 30 minutes instead of 60 minutes just to make the results more visible.

However, using the hour subdial, you can tell whether the half hour you are counting is the “first” half-hour of the hour (that is, from 1 minute to 30 minutes) or the “second” half-hour of the hour (that is, from 31 minutes to 60 minutes). You can easily understand what it is.

F. The Hour Subdial

When you activate the chronometer, the elapsed time is displayed. There are 12 in all, which is the maximum capacity of a luxury watch chronometer.

G. Reset Chronograph Button

How do you reset them to 0? Very easy! Press the button at 2 o’clock to start the chronograph and press it again to stop the chronograph. Alternatively, the chronograph can be reset by pressing the button at 4 o’clock (G.).

Chronograph Subdials Explained

The most common subdials are found on chronograph watches. A chronograph is basically a stopwatch. Pushers on either side of the watch case allow the wearer to activate the chronograph second hand or stopwatch function.

Chronograph subdials are sometimes called “registers” and track the total elapsed minutes and hours measured by the chronograph. Another subdial also measures seconds to within 1/10th of a second for added accuracy. The subdials are designed to improve the overall readability of the measured elapsed time by separating the seconds, minutes, and hours. By summing the numbers read by the subdials, the elapsed time since the chronograph was started can be calculated.

Power Reserve Indicator Subdial

Power Reserve Indicator Subdial

Some mechanical watches (those that rely on a mainspring to power the watch) have subdials that indicate the amount of energy stored before the watch stops.

GMT Subdial

GMT watches became popular in the 1950s when private air travel was a growing form of transportation, allowing them to track a second time zone. The second time zone is usually set and read by a rotating GMT bezel and GMT hand. However, some GMT watches actually have a GMT subdial showing his second time instead.

GMT Subdial
Moon Phase Subdial

Moon Phase Subdial

Unlike the other subdials in the list that contain numbers, the Moonphase subdial displays the phases of the moon (i.e. new moon, first quarter, crescent, full moon, etc.).

Day of the Week Subdial

Another sub-dial that is less traditionally classified as a sub-dial is the day of the week subdial. Like the moon phases, the day of the week is displayed through an opening in the main dial to indicate the current date. One of this watch models that features a week-day subdial is the Rolex Day-Date.

Day of the week Subdial

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