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        SeiyaJapan blog

        Citizen Series Eight

        Citizen Series Eight

        The series 8 has debuted with a dynamic design and all-new automatic movement.
        (Honestly, it has been for sale for domestically within Japan for several years since 2008.)
        "Improved magnetic resistance performance"
        The accuracy of automatic watches are negatively affected by the magnetism generated by smartphones, tablets, and PCs.
        "Citizen Series Eight" has improved its magnetic resistance performance by using a new type of material in the hairspring.
        With a magnetic resistance performance of 16000A/m, it remains unaffected down to a distance of 1 cm when coming into contact with magnets.
        Typical watches are only resistant up to 4800A/m.
        Magnetic resistance performance
        Magnetism resistance
        (in case of direct current magnetic field)
        Type 1 antimagnetic watch
        (magnetic resistant watch)
        Up to 4,800 A/m
        A magnetic resistant watch almost always maintains its performance when placed at 5 cm from magnetic field generating devices of everyday life.
        Type 2 antimagnetic watch
        (super magnetic resistant watch)
        Up to 16,000 A/m
        A super magnetic resistant watch almost always maintains its performance when placed at 1 cm from magnetic field generating devices of everyday life.
          "28800 beats per hour movement"
        The movement has a good balance between high -performance and high-precision at 28800ph.
        There are two types of movement, Cal 0950 & Cal 9051.
        Cal 0950 -- -870 & 830 Mechanical --
        •  -5 ~ +10 sec per days 
        • 50 hours power reserve

        Cal 9051 -- -831 Mechanical --

        •  -10 ~ +20 sec per days 
        • 42 hours power reserve


        -870 Mecanical-
        The Cal0950 simplistic model 
        The simple yet eye-catching design combines both hairline and mirror finishes.
        -830 Mecanical-
        The Cal0950 beautiful dial model. 
        This model features a fresh new look combining a metal lattice with a mother of pearl layer on the dial. 
        - 831 Mechanical -
        A great entry model for Series 8 comes equipped with the Cal 9051 
        The 831 model has the same eye-catching octagonal case as the 830 model, but with a simpler monotone dial.



        Scratch-resistant "Dia-Shiled" "Duratect"

        Scratch-resistant "Dia-Shiled" "Duratect"

        I often get asked just how tough (the case and bracelet) the metal Dia-Schild and Duratect (scratch-resistant) metal truly is.


        I created a chart for easy reference. 
        They are lined up in order of toughness according to Hv (Vickers Hardness) ranking system. 
        They get tougher the further you go to the right.


        "DiaShield" is about 2-3 times harder than Stainless Steel. 

        "Duratect/DLC" is about 5-7 times harder.

        "Duratect α" is about 10 times harder. It is the same as Sapphire crystal.
        It is used in models such as the AT9050-58A "Citizen Exceed".


        There is this much of a difference between Seiko and Citizen.(SEIKO may currently be developing new technology.)


        The DLC(Diamond-like Carbon) doesn't mean that is is just as hard as a diamond、but that it has a structure similar to a diamond.


        As a final note, even though they are tough to scratch, it doesn't mean that they can't be.




        I found this information on the site listed below.

        Seiko Site

        Citizen site

        I referred to this site for the sapphire glass and diamond hardness. 

        Since it is not possible to provided detailed information, so the listed information may vary.

        Please use the information as a reference only. 

        "The Citizen" is the pride of Japan

        "The Citizen" is the pride of Japan

        In Japan, there are watches that can’t be gotten overseas, which means that countless individuals are unaware of their exquisiteness. This is The Citizen

        This piece has a minuscule 5 second time reading error throughout the year. The high precision of Citizen was made to perfection with Quartz.  

        One of the first points taken was not consideration was the quartz oscillators. 

        The crystal oscillators act like a quartz heart in this piece. 
        The wavelengths of the crystal oscillators are monitored for 6 months, upon which those with stable frequencies are selected. 
        Furthermore, the wavelengths are continuously monitored after pairing it into the movement, and any inadequate ones are removed. 
        This is how they achieve an error margin of 5 seconds. 

        Another appealing feature is the frequency temperature compensation function, since temperature has the greatest affect on quartz accuracy.

        Quartz, which functions properly at 25C, will experience a daily delay of 0.1 seconds with a 5C temperature difference. 

        That is why The Citizen comes equipped with the frequency temperature compensation function. 

        It measures the temperature and makes adjustments 1 minute beforehand. 

        The frequency temperature compensation continues to function even with frequent temperature changes.

        Finally, each piece is assembled one by one to perfection by a master craftsman.
        • It now comes with an “exact midnight” date changing calendar function. 
        • Perpetual calendar
        • Convenient time zone setting function for overseas travel

        A wristwatch boasted as the jewel of Japan; this is The Citizen.

        Refer to

        About the Quartz watch Second hand alignment

        About the Quartz watch Second hand alignment

         About the Quartz watch Second hand alignment

        There are times when the second hand doesn’t quite hit the marker.second hand mis-alignment

        I have received many questions regarding this from several customers asking why this was happening. I found an easy-to-understand explanation on the Citizen watch site, so I am posting a summary of it. 

        The second hand’s movement is controlled by the gears. There is an intentional space placed in-between each gear.  That space(playfully) is called "backlash". This backlash is the cause of the second hand mis-alignment The gear space causes the place where the second hand stops to slip a little.

         An adequate backlash is essential for smooth gear operation. To put it quite simply, the gears would stop turning if the backlash was too small.

        The reasons for the necessity of an adequate backlash are outlined below. 

        1.Thermal expansion
        The gears expand due to the heat from friction. A difference of just 10C can have an affect on gear alignment, even if they are small. The backlash is essential in minimizing that affect. 

        2.  Distortion
        The gears of a watch take on pressure as they mov, causing these small parts to become slightly distorted. The backlash is necessary to minimize distortion.

         3. Impact
        Watches are sometimes dropped. The will cause the gears to break upon direct impact if there isn’t a bit of slack. 

         4. Wear resistance
        By creating a backlash, it is easier for lubricant to get up into the gearspreventing abrasion. 

        5.Parts Standardization
        The parts in a watch are not all exactly the same size, strictly due to error, despite an increase in machining accuracy.(Of course this is within the acceptable range for the maker).In order to account for this error, it is important to put the backlash into place to ensure that all parts turn smoothly..
        This might be the main reason.

        In conclusion

        The Backlash is an essential part of the gear, and can’t be removed 100%.

        While it is possible to reduce the backlash by improving the gear manufacturing precision and assembly method, doing so would have an impact on thermal expansion, impact, and wear resistance etc.

        In other words, an adequate backlash is the solution for balancing durability, accuracy, and refined hand movement within the watch.

        That is all of the available information from the Citizen watch site.

        Citizen watch site (Japanses)
        Picture : Wikipedia

        The rest is what I have been able to determine speaking from personal experience.

        SEIKO has come out with Backlash auto-adjust mechanism, which they use in the Grand Seiko Quartz for reducing second hand mis-alignment.

        The Grand Seiko Quartz uses the power of the spring to reduce the slight second hand  mis-alignment that is created by the backlash as much as possible. (It’s like stopping the motion of a moving object with the power of a spring, which is difficult to wrap my head around.)

        Even though the misalignment is far less noticeable in Grand Seiko is n comparison to any other watch, even the meticulously crafted Grand Seiko suffers from a slight second hand mis-alignment. (Sorry SEIKO)

        About SEIKO Backlash auto-adjust mechanism,

        Seiya Kobayashi

        About the OCW-T200 series Mobile Link "Oceanus Connected"

        About the OCW-T200 series Mobile Link  "Oceanus Connected"

        The OCW-T200 easily connects to your smartphone via Bluetooth where you can check the information available on Oceanus.


        Top screen


        History of Self Adjustment

        You can view its history of self adjustment records to view time zone corrections via radio waves and Bluetooth.



         Solar Power Charging Transition

        The amount of energy generated by the solar cell of the watch is displayed.


        Latest Updates

        It updates with the latest time zone and summer time information from each country.

        Phone finder 

        It searches for your smartphone.