Manufactured by the Japanese Casio Computer Co. Ltd company, the Casio F-91 watch is part of the Casio F-series of digital watches.
It was in 1991 when we first saw on the market the original Casio F-91 W, but this doesn’t mean the watch lost its popularity since then. It’s a simple, dependable and not sophisticated, very user-friendly watch, which is why it’s still one of the most popular watches out there. You may still find it in various variants. Even though Casio doesn’t actually tell us what are the selling numbers, we can only guess it’s doing pretty well.
A closer look
There are many things that explain the popularity of the watch, and we start randomly with the net and split time (lap) functions. The watch also has a 1/100 second stopwatch with a count up to 59:59.99 (almost one hour). You may set an hourly time beep and a single daily alarm that lasts 20 seconds.
We also notice the automatic calendar, which is always good to have. We don’t like though the fact the watch doesn’t come with an auto-adjustment for the leap years since the watch doesn’t record the year. For instance, February comes with 28 days.
A green LED backlight is placed on the left of the display for illumination, but don’t expect to see much in the dark as the light is rather weak.
As for the accuracy, the manufacturer claims the watch is accurate to +/- 30 seconds per month.
A strong feature of the watch is for sure the CR2016 3-volt lithium button cell that lasts for seven years if you’re using the 20 seconds alarm and only one second of light daily. As no one can actually use the watch like that, chances are the battery lasts more or less.
Many watches today are water resistant and the F-91 comes with a dependable rubber seal placed between the steel back and the case. It doesn’t feature though seals for the buttons. The buttons are tightly fitted so water doesn’t really get inside due to the surface tension. The watch takes only some point of water pressure though. Even though the Casio F-91 is marked as Water Resist, we do need to check the various values on that. For instance, the F91W-1 has “30M/3Bar” resistance and this means you may use if on regular basics as the watch takes well few splashes or rain. You can’t actually take it when bathing, swimming, showering or developing other water related activities.
If you get yourself the F-91WC-2AEF, we see the watch actually handles minor splashing.
In a nutshell, the F-91 may take well water submersion every now and then, if the buttons aren’t pressed, but you shouldn’t do it very often.
How to use it and set the time
The F91 includes a daily alarm mode and uses a 24-hour display option.
You may easily control the watch with three side-mounted pushbuttons. You should use the upper left button to turn on the backlight, but also to cancel the alarm, mark the split time, select various settings or to reset the stopwatch.
The lower left button is to choose the modes of the watch: alarm, stopwatch, time/date adjustment, and time display.
You may use the button on the right to start and stop the stopwatch, but also to change the setting that you’re adjusting at some time. You may also switch between the 12- and 24-hour modes when using this button.
When the watch is in time mode, as you press this button for three seconds you can see the display read “Casio”. This happens when the watch has genuine parts or made under legitimate license. When you press all three buttons at the same time, you notice how all the cells fill on the LCD, until you press any other button again.
If you want to set the time or date, you need to press the lower left button three times, which puts the watch to time adjustment mode. You may go through seconds, hours, minutes, month, date, day and normal mode by using the top left button.
You get to adjust the flashing value displayed by pressing the right button. You may even zeroed the seconds. If this happens under 30 seconds, the watch zeros in the beginning of the current minute. If it takes more than 30 seconds, it begins the next minute as displayed. You may return the watch to normal mode when you are done with the adjustments by pressing the bottom left button.
The watch shows you seconds, minute, hour, day of the week and day of the month, but also the signs PM or 24H at all times. You find out about the alarm signal status (bar of lines) and also the hourly signal status.
When the watch is in the stopwatch mode, you may read seconds, minutes and hundredths of a second.
This isn’t the most sophisticated watch out there, for sure. As a matter of fact, the Casio F91 doesn’t come with impressive functions. Low priced, lightweight and dependable for the things you need the most when it comes to a watch (like, “what time is it?”), the watch is always a great option, which may explain its popularity for such a long time.