Subdials are the mini-dials that sit on the watch face or dial. Also known as auxiliary dials, subdials serve different functions—like tracking lapsed seconds, minutes, and hours, the phases of the moon, a second time zone —across mechanical and specialty watches like chronographs, calendars, and GMT watches.
Here we break down the different purposes subdials can serve on particular watches, including the chronograph and moon phase.
Chronograph Subdials
The most common subdials are found on chronograph watches. In the most basic terms, a chronograph is a stopwatch. By pressing the pushers on either side of the watch case, the wearer can activate the chronograph seconds hand or stop watch functionality.
A chronograph’s subdials are sometimes referred to as “registers” that keep track of the total elapsed minutes and hours timed with the chronograph. Another subdial also measures the seconds, down to 1/10th of a second for added accuracy.
The subdials are meant to improve the overall readability of the measured elapsed time by breaking down the seconds, minutes, and hours separately. By adding up the figures you read in the subdial, you can calculate how much time as passed since you started the chronograph.
Power Reserve Indicator Subdial
Some mechanical watches (which rely on a mainspring to power the watch) will have a subdial that reads out how much stored energy the watch has left before it stops running.
GMT Subdial
Popularized during the 1950s when commercial air travel was a growing mode of transportation, GMT watches allow you to keep track of a second time zone. Typically, the second time zone is set and read via a rotating GMT bezel and a GMT hand.However, select GMT watches will actually feature a GMT subdial were the second time is displayed instead.
Moon Phase Subdial
Unlike the other subdials on the list which feature numbers, the moon phase subdial features a depiction of the moon through an aperture (or window) that tracks the phase of the moon (i.e. new, waxing, crescent, full, etc.)
Day of the Week Subdial
Another less traditionally thought of but still classified as a subdial is the day of the week subdial. Similar to the moon phase, the day of the week appears through an aperture on the main dial and reads out the respective day. One watch model that prominently features a day of the week subdial is the Rolex Day Date.
As a seasoned horology enthusiast with a profound understanding of timepieces and their intricate mechanisms, I bring forth a wealth of knowledge to illuminate the fascinating world of watch complications, specifically delving into the realm of subdials. My passion for horology has led me to explore and appreciate the nuances of various timekeeping instruments, from classic designs to cutting-edge innovations. Allow me to shed light on the concepts intertwined with the subdials featured in the article.
Chronograph Subdials:
The chronograph subdials, commonly known as "registers," are pivotal components in chronograph watches. My expertise extends to the fundamental understanding that a chronograph is essentially a stopwatch, activated by pressing the pushers on the watch case. The subdials, in this context, function as meticulous timekeepers, recording elapsed minutes and hours with precision. Moreover, they provide a secondary subdial for tracking seconds, often down to 1/10th of a second, enhancing the accuracy of time measurements. This meticulous breakdown of time into separate units significantly improves readability.
Power Reserve Indicator Subdial:
In the realm of mechanical watches powered by mainsprings, I am well-versed in the concept of power reserve indicator subdials. These subdials serve the essential function of displaying the remaining stored energy within the watch before it ceases to operate. This feature is crucial for wearers to gauge when their timepiece requires winding, preventing unexpected stoppages.
GMT Subdial:
My expertise extends to GMT watches, a category that gained prominence in the era of growing commercial air travel during the 1950s. GMT subdials play a pivotal role in these watches by allowing users to monitor a second time zone. While traditional GMT watches utilize rotating bezels and dedicated hands, select models feature GMT subdials that directly display the second time zone, offering a convenient alternative.
Moon Phase Subdial:
Delving into the poetic realm of moon phase complications, I understand the intricacies of moon phase subdials. Unlike numerical indicators, these subdials feature an artistic depiction of the moon through an aperture, portraying its various phases such as new, waxing, crescent, and full. My expertise encompasses the appreciation of the craftsmanship involved in capturing the celestial dance within the confined space of a watch dial.
Day of the Week Subdial:
Expanding beyond conventional expectations, I am familiar with the less commonly considered day of the week subdial. Similar to the moon phase subdial, this feature displays the day through an aperture on the main dial. A notable example is the Rolex Day Date, a prestigious model that prominently showcases the day of the week through a dedicated subdial.
In summary, my comprehensive understanding of chronographs, power reserve indicators, GMT complications, moon phase displays, and day of the week indicators positions me as an authority on the multifaceted world of subdials and watch complications.
