Comparison Casio G-Shock GST-B400-1A vs Casio PRG-270-1

A caliber can be described as the type of movement used in a watch. It is expensive and impractical to design a unique movement for each watch model, so most manufacturers often use the same movement in different watch models, sometimes with significantly different designs. The term "caliber" is due to the fact that initially the type of movement was designated by a number (in inch lines) corresponding to its largest size; however, today unique names or alphanumeric indices that are not directly related to sizes are widely used.

Knowing the name of the caliber on which the watch you are interested in is built, you can, if desired, find more detailed information about the mechanism and determine how its characteristics meet your requirements.

The accuracy of the rate is usually determined by the largest error — the deviation from the reference time, which can occur in a month when the watch is constantly running in normal mode. Accordingly, the smaller the number in this paragraph, the more accurate the clock. In addition, the accuracy of the movement is a kind of status indicator: if the error exceeds the values stated in the characteristics, this may indicate a malfunction in the mechanism.

If the accuracy indicators are the same both in advance and in lag, one number is indicated in the characteristics — for example, 30 sec / month (i.e. +/-30 sec / month); however, many mechanisms have unequal deviations, for example -15/+25 sec/month. Also note that this parameter is relevant only for quartz watches (see “Movement type”): in mechanical models, the accuracy of the rate is noticeably lower, it is measured in seconds not per month, but per day.

The amount of time that the watch is able to operate normally without winding the spring or changing/recharging the battery (for more details, see "Power source"). Modern mechanical watches (see “Movement type”) have a standard power reserve of 40+/-5 hours. However, this parameter is usually indicated for the simplest mode of operation, without the use of additional functions such as a chronograph(see “Functions / Capabilities” ), which also “eat up” the plant. Thus, such a watch is supposed to be wound every day, but nothing will happen if you miss the usual time and remember to wind it a few hours later than usual.

In turn, for quartz watches, the power reserve is often not indicated in the specifications. This is due to the fact that this parameter, firstly, is quite large compared to mechanical models (it would be measured in tens of days rather than hours), and secondly, it strongly depends on a number of external factors (for example, the quality of the next batteries). Therefore, it is very difficult, if not impossible, to reliably determine the power reserve in such cases.

— Arrow. A classic-looking dial with divisions to indicate the time and at least two hands — hour and minute — moving in a circle. This option limits the ability to display additional information and any additional function significantly complicates the design, but this classic allows you to make watches in any design, which is so appreciated.

— Digital. As the name implies, the time in such a watch is displayed by numbers, while the role of the dial itself is played by a liquid crystal screen. It is this type of watch that is commonly called "electronic". LCD screens are much more convenient for displaying additional information than arrow dials, they provide more options (for example, a stopwatch can easily count tenths and even hundredths of a second).

— Mixed. An option that combines both of the above types. Usually it is an arrow dial, supplemented by a small LCD screen. Thus, in one model, the advantages of both types of dials are combined — the visibility of the arrows and the versatility of the screen. Watches of this type can only be quartz.

— LED. In fact, it is a variation of the digital dials described above, in which LED screens are used instead of LCD matrices. The key feature of such watches is that they are, by definition, backlit — in the sense that the image itself glows. In addition, the colour of the image may vary, and many o...f these models have a bright and unusual appearance. On the other hand, such dials consume more energy than traditional liquid crystal ones, which consequently affects battery life. In some models, this moment is partly offset by the fact that the screen does not work all the time, but turns on for a few seconds at the touch of a button; however, this also creates certain inconveniences — in order to find out the time, you have to make extra movements.

— Disk. A rather unusual type of dials based on the use of rotating disks with numbers printed on them. There are virtually no arrows in the disk dials, their role is played by special windows in which the readings of a particular disk are displayed. Such watches differ in their original appearance, but in terms of convenience they are still somewhat inferior to traditional watch models (especially since the second hand — or rather, the disk — is usually not provided for in their design). Thus, this option has not received much distribution.

The type of markup used on the main watch face. This parameter is relevant for models with hands (see "Dial Type"), while the type of marking is indicated only on the main scale — additional marks on the bezel are not taken into account (although markings on the additional world time dial may be taken into account).

This parameter does not affect the functionality of the watch, and the choice depends solely on the tastes of the owner. The main types of markings found in modern watches include Arabic and Roman numerals (which can be supplemented with marks), a combination of these numbers, as well as the simplest marks themselves. Here are the main features of these options and their combinations:

— Arabic. Dials that have marks only in the form of Arabic numerals — that is, standard modern numbers "1", "2", etc. In this way, both all divisions of the dial, and only some of them (for example, 3, 6, 9 and 12 o'clock). However, anyway, there are no other types of marks in such watches.

— Roman. Dials that are marked only in the form of Roman numerals — combinations of the symbols I, V, X. This marking gives the watch a peculiar style, but it can take some getting used to — and therefore is less common than Arabic numerals. Again, in this case we are talking about dials that do not carry any other designations, excep...t for numbers of this type.

— Tags. Minimalistic design, in which the divisions on the dial are indicated only by a label, without a signature. Most often, marks are applied to all twelve hours; exceptions to this rule are possible, but they are rare nowadays. It should be noted that such a design can be found both in classic watches with minimal functionality and in advanced models with extensive features: in the first case, the marks give the product a neat appearance, in the second, they save space on the dial for additional scales and markings. Theoretically, such markup is not as convenient as notation with numbers; however, almost all dials in modern wristwatches use a 12-hour scale with a standard location of marks, so with a little habit you can completely do without numbers — the position of the mark on the scale already carries enough information.

— Arabic + Roman. Dials that combine both types of numbers described above at once (sometimes also with marks; in this case, the presence of marks is not specified). The most popular type of watch with this feature is the world clock (see "Features and Features"), where one dial is marked with Arabic numerals and the other with Roman numerals. There is also a combination of these symbols on the same scale — for example, when 3 and 9 hours are indicated by ordinary numerals, and 6 and 12 by Roman numerals. However, neither one nor the other variant received special distribution.

— Labels + Arabic. Dials, in which part of the markings are applied with Arabic numerals, part with marks (for both, see above). Moreover, the ratio of both can be different: for example, in some models there is only one digit (usually "12"); in others, key positions "3", "6", "9" and "12" are designated by numbers; thirdly, part of the dial is occupied by a display, near which the numbers simply do not fit and you have to manage with marks, etc.

— Marks + Roman. The dials, in which part of the markings are applied with marks, part with Roman numerals. This markup method is generally similar to the “labels + Arabic” option described above (and can also provide different design options).

Clock face background colour. Indicated for models with pointer or combination dials (see "Dial type"); in purely electronic models, usually, either a grey substrate (for conventional LCDs) or a dark base (for LEDs) is used.

The most popular in modern watches are black, white, silver and blue dials. However, in addition to this, other shades can be found on the market — in particular, beige, yellow, green, golden, brown, red, orange, pink, grey and purple. A special case are watches with chameleon glasses (see below).

Some models are available in several colour options, in such cases these options are listed separated by commas — for example, "white, red, silver." If the dial is painted simultaneously in 2 or 3 colours, they are indicated as a combination — for example, "white with red" or "white with yellow and red". And multi-coloured models include models in which more than 3 colours are used for the dial.

A function found in models with mixed dials (see the relevant paragraph) or additional scales. One of the disadvantages of such models is that in a certain position, the hands can cover the screens or scales, making it difficult to read the information on them. For such cases, the function of moving the hands is provided: at the user's command, the hands move to a position in which they do not cover additional elements of the dial. Also, on command, the arrows can be returned “to their place”; in addition, in some models, the return occurs automatically after a certain time.

How to illuminate the clock face.

— Luminescent coating. A variant used in pointer dials: the hands, and sometimes the scale, are coated with a “phosphorus” coating that glows in the dark. This method of backlighting is inexpensive and can be used even in low-cost models; in addition, it does not require batteries and is suitable even for mechanical watches. On the other hand, coverage is often not as effective as it should be. The fact is that for work it must be “charged” from the sun or another bright light source, and this “charge” is enough for an average of 5-6 hours, and already in the first couple of hours the brightness of the glow drops noticeably.

— Electronic. Illumination based on LEDs or other miniature light sources. Usually, it does not work constantly, but turns on and off by pressing a special button; the exception is LED dials (see "Dial Type"). The main advantage of electronic backlighting is efficiency: it is guaranteed to be enough to view the image on the dial. In addition, such systems do not depend on external illumination, in contrast to the luminescent coatings described above. On the other hand, the lighting requires a battery to operate; therefore, this type of illumination is found exclusively in quartz watches (see “Mechanism type”).

— Luminescent coating / electronic. Systems that combine both types of illumination described above. This option is f...ound mainly among models with combined dials: the hands are coated with a luminous coating, and the electronic backlight is intended mainly for displays and additional scales (and also as a backup option for the hands). The combined backlight is very convenient, however, such watches are somewhat more expensive.

— Tritium illumination. Illumination option found on premium pointer dials. Miniature flasks filled with tritium, a radioactive form of hydrogen, are responsible for the illumination in such models; from the inside, the surface of such flasks is covered with a phosphor, which glows under the influence of tritium radiation. Separately, we note that this radiation does not pose a danger to humans: it does not go beyond the bulb, and even inside its intensity is extremely low. Tritium illumination is expensive, but it is extremely convenient from a practical point of view: "flashlights" work constantly, without batteries and regardless of external lighting, and shine significantly brighter than a conventional luminescent coating. However due to the decay of tritium, they gradually lose their brightness, but this happens very slowly: it takes 12 years to reduce by half, and at least 20 years for the backlight to become useless.

— Alarm clock. A classic alarm clock is an audible signal that works at a time specified by the user. It can be used not only for getting up, but also as a reminder of a particular event. Note that in mechanical models (see "Type of mechanism") this function is almost never found.

— Stopwatch. A traditional stopwatch is a function that allows you to measure time intervals with an accuracy of seconds, or even fractions of a second. In modern watches, you can find two types of stopwatches. The first is the solutions used in models with displays (in other words, in watches with electronic and combined dials). In such devices, the countdown of seconds is displayed on the screen and is accurate to a tenth or even a hundredth of a second; Also, such stopwatches can have various additional functions: counting intermediate results for control points or laps, saving the results of the last measurement, etc.
The second type of stopwatch found in the arrow dials is the arrow on the main axis, which can be started and stopped at the request of the user. This is a rather rare option — for the reason that most often such an arrow is used in combination with additional scales and is no longer a stopwatch, but a chronograph (see below). And in watches where there are no chronograph scales, a rather unusual format for the operation of such a hand can be provided: in normal mode, it works like a standard second,...and when the watch is switched to stopwatch mode, it moves to zero and stops before the countdown begins.

— Timer. Countdown function; at the end of the countdown, an audible signal sounds. This function is convenient in cases where you need to measure a strictly defined period of time — for example, when cooking in the kitchen: “starting” the timer for the desired period is much more convenient than counting the hour you need to set the alarm.

— Day of the week. Ability to display the day of the week on the watch face. It is found both in watches with displays and in purely analogue models — they use a mechanical indicator for 7 days.

— Day of the month. The ability to display the current day of the month on the clock face. It can be either a number on the display or a mechanical indicator in the form of a window with a number. Note that in the latter case, regular adjustment of the calendar is required: the mechanical pointer is designed for 31 days, and if there are less than 31 days in the past month, the displayed date will have to be “scrolled” forward.

— Month of the year. Ability to display the current month on the watch face. Usually, it is combined with an indicator of the day of the month, and often also the day of the week; thus, the presence of this pointer means that the watch is equipped with a full-fledged calendar. Most often, the display is responsible for this function, but there are also purely arrow models with similar equipment. The month indicator of the year is often synchronized with the day indicator — so that the watch itself determines how many days are in the current month and after which day you need to switch to the first number.

— World time. The ability to use the clock to determine the time in other time zones than the current one. The specific way in which such a function is implemented may vary. Thus, the most popular option in hand models (see "Dial type") is the presence of an additional dial, on which the time of the time zone of interest is set. This format is convenient in cases where you constantly have to deal with a certain region — for example, to communicate with relatives or business partners from a particular country. Another option is the indexes on the rotating bezel (see below), corresponding to the main time zones of the world; to determine the world time, you need to turn the bezel so that the current time zone is opposite the hour hand — then the remaining marks will be opposite those divisions of the dial that correspond to the time in these time zones. This format is convenient for frequent change of time zones — in particular, it is found in watches for sailors. And models with digital dials usually provide switching the screen between the current and additional time zone (zones).


— 12/24 hour time format. This feature is indicated only for watches with pointer dials (and certain pointer-electronic models, see "Dial type"). It means that in addition to the main 12-hour scale, the watch also has a small dial with 24-hour markings. It allows you to determine what time the main scale shows — before or after noon: for example, at 6 pm the main dial will indicate 6 o'clock, the additional one — at 18 o'clock. — for example, in the conditions of a polar day / night, or during a long stay underground.
As for watches with electronic dials, even the 12-hour format is supplemented with the note "AM" or "PM" ("am" and "pm" respectively); for example, 20:00 would be 8:00 PM. So in such models there is simply no need to provide special functions for determining the time of day.

— The phases of the moon. The presence of an indicator in the watch that displays the current phase of the moon. Many processes on Earth depend on the phases of the Moon (in particular, the general physical and mental state of people), a number of signs are associated with them — not always 100% reliable, but not having an unequivocal refutation. A separate category of watches with a lunar calendar — "fishing" and "seafaring" models; the latter may even provide a separate tide calendar.

— Chronograph. Analogue of a stopwatch used in watches with pointer dials (see "Dial type"). Such watches have several additional small scales, each of which performs its own function. For example, one of these scales can be responsible for counting minutes (up to half an hour), the second — for counting hours (up to 12 hours), the third is the usual second hand, and the hand for counting seconds is located on the central axis and remains stationary until the chronograph is turned on.

— Tachymeter. A device for measuring the speed of movement by the time during which the measured section was passed. The tachymeter most often has the form of an additional scale for a stopwatch, and to measure the speed, you need to measure the time it takes to pass the control section with a stopwatch and see what number on the tachymeter scale the stopped arrow points to. In this case, the measurement time should not exceed a minute (otherwise the arrow will go to the second circle, and the readings will be unreliable), and additional calculations may be required to determine the final result. However, anyway, it is much more convenient to use tachymeter data to determine speed than stopwatch readings.

— Slide rule. Built-in mechanical calculator for some simple mathematical calculations, primarily multiplication and division. Such a device can be useful, in particular, for calculating travel time, fuel consumption, transferring money from one currency to another, etc. In hours, a slide rule usually consists of two rings with divisions (hence the second name for this function is a calculator ring ). One of these rings is motionless, and the second rotates freely; combining the marks on both scales according to certain rules, the user gets the desired result. Note that the slide rule is not as accurate as an electronic calculator and is more difficult to handle; on the other hand, with a minimum skill, elementary calculations on it can be carried out much faster than on the same calculator.

— Compass. A traditional compass is a device for determining cardinal directions. The accuracy of built-in compasses is usually not high, but they can be very useful for simple tasks or as a last resort when other navigational devices are not available.

— Altimeter (altimeter). A device for measuring the current height of the terrain. Often combined with a barometer (see below), in such cases the difference in pressure between the reference level and the current location is used to measure altitude. Technically, in this way it is possible to measure the height both above sea level and relative to a certain place taken as a standard; actual altimeter capabilities vary by watch model. Watches with this function are designed primarily for climbers and mountain hikers.

— Thermometer. Thermometers in watches are usually designed to measure the temperature of the surrounding air. This feature is found mainly in advanced sports models. It can be useful both for a general assessment of the environment, and for specific tasks such as weather forecasting, calculating the current altitude, etc.

— Barometer. A device for measuring atmospheric pressure. Data from the barometer allows you to assess the weather conditions and their favorableness for a certain type of activity — in particular, fishing. In addition, they can be used to predict changes in the weather: for example, a sharp drop in pressure is often a sign of an approaching storm. Also, the operation of the altimeter (see above) is often based precisely on the readings of the barometer.

— Bluetooth. The Bluetooth wireless interface is designed to communicate between various electronic devices over relatively short distances — up to 10 m. In wristwatches, it is mainly used to communicate with a smartphone or other gadget. The functionality of such a connection may be different, but anyway, it is much narrower than in smartwatches. The most popular features include displaying notifications from Facebook and/or Twitter on the watch, using the watch as a remote control for music or video, as well as setting the world time (determining the time zone from data from an external device).

— GPS module. Built-in satellite navigation module that allows you to determine the current geographic coordinates of the device. How this data is used may vary depending on the watch model. So, in some models, data on time zones in different countries are sewn in, and based on the current coordinates, the device can determine the exact local time. Another option is to record the routes (tracks) traveled. Some watches use GPS data for altimeter operation (see related paragraph). Models with Bluetooth may provide the ability to work as an external sensor for a smartphone or other gadget (it is believed that the hand position of the sensor improves accuracy). But it is difficult to provide full-fledged navigation in traditional watches; wearable gadgets with such functionality usually refer to either smartwatches or specialized navigators.

— Synchronization by radio channel. This function allows the watch to receive special time radio signals. These signals are transmitted over a special dedicated channel several times a day, and the exact time data is received from atomic chronometers used in scientific institutes. The error of such chronometers is 1 second for several thousand or even millions of years; accordingly, the accuracy of the clock synchronized with them is almost absolute. At the same time, note that precise time radio signals are not available in all countries of the world — so before buying such a watch, it's ok to check whether they will work in your region.

— Chronometer. In this case, the designation "chronometer" is used for high-precision models that are certified by the Swiss Chronometer Certification Centre (COSC). To obtain such a certificate, a watch must pass a fairly rigorous test, checking not only for overall accuracy, but also for the ability to maintain it with changes in case position and ambient temperature. At the same time, it should be noted that in fact "chronometric" accuracy is required extremely rarely, and it affects the cost of watches quite noticeably. So compliance with the COSC requirements is not so much a practically significant moment as an indicator of the high class of watches and the status of their owner.

— Pedometer. Built-in counter of the number of steps taken by the user. This feature is found predominantly on sport touring models equipped with Bluetooth (see above) and digital or combination watch faces (see "Dial Type"). To count steps, usually, data from the built-in accelerometer is used, and the measurement results can at least be transmitted to a smartphone or other gadget, and in some models they can also be displayed on their own screen. However, it's ok to clarify the specific features of the functionality of a watch with a pedometer separately.

— Phone search. Feature exclusive to Bluetooth models (see above). In accordance with the name, it facilitates the search for a “lost” phone located in close proximity (for example, forgotten in one of the home rooms): just give a command from the clock and the device will “respond” with a sound signal. Usually, to use this function, you need to install a special application (other additional functions are usually implemented through it, if available — for example, a pedometer).