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The possibility of a mission timer was first discussed on the forum in 2007. At that time, the movement I wanted to use had been discontinued by ETA and I didn’t know enough about the successor. By the time I decided to proceed, the chosen movement (ETA 251.264 BD) was not a stock item with ETA, movements were manufactured to order with a long lead time. The BD suffix means that the movement incorporates PreciDrive and PowerDrive technologies with a typical accuracy of +/- 10 seconds per annum.
What Are Mission Timers?
A Mission Timer is a watch concept that Sinn evolved in the late 1990s, specifically in the EZM1. The concept is very simple. It needs to tell the time; it needs to measure elapsed time and it needs a bezel. And it must do all these things with utmost clarity, in every situation, so simplicity is key to the dial. Not to mention the case design must also consider hand combination, durability and water resistance.
Whilst the ETA 251.264 is capable of being a 3 register chronograph, the sub-dials on the Precista Mission Timer are not used to keep the dial very legible, only the running seconds (at 12), chronograph seconds hand and chronograph 60 minute recorder (the aeroplane tipped hand) are used in addition to the hour and minute hand.
How to use a Mission Timer
The chronograph is operated by means of pushers A and B. The measurement starts when button A is pressed once and then stopped when pressed again. Press B to reset the chronograph to the zero position.
It is possible to also measure split/lap times by pressing A to start the chronograph then pressing B to temporarily pause the hands, after pressing B again the hands will jump to the elapsed time since pusher A was first pressed. Pressing A to fully stop the chronograph then B will reset the hands to zero.
Using the bezel to measure time
The bezel can be moved manually anti-clockwise. It can be used in a number of ways, including to measure important lengths of time. For example, you can set the marking to the beginning of the time span to be measured, or you can use it to indicate the end of a given span of time. The bezel triangle and numbers are luminous.
The Bracelet screws are not fully tightened to allow for easy first-time adjustment. After sizing please tighten and we suggest using a removable threadlock such as Loctite Blue 242 to secure the screws.
CASE
• 316L stainless steel, choice of bead blasted or full DLC finish
• Diameter: 40mm across centre, 43.4mm inc. Crown
• Lug to lug height: 44.5mm
• Thickness: 14.5mm to the top of the crystal
• Lug spacing: 22mm
• Anti-magnetic: 20,000 A/m with anti-magnetic cover
• Water resistance: 100 metres
• Weight: 170 grammes including bracelet
• Screw back
• 120 click unidirectional bezel
• Choice of steel or ceramic bezel
DIAL
• Semi-matte black with luminous hour indices, 3-6-9
• Super-Luminova C3
HANDS
• White painted, luminous filled
• Super-Luminova C3
SAPPHIRE
• Flat sapphire with anti-reflective coating on the underside
MOVEMENT
• ETA 251.264 BD with 27 jewels, 394 silver oxide battery
BRACELET
• Stainless steel or DLC bracelet with custom fitted solid end links and adjustable twin-pusher clasp; screwed links for adjustment
Supplied in a watch traveling case with 24 months guarantee.
All watches are guaranteed against defective workmanship for 24 months from
date of purchase and the guarantee for the first 12 months applies to the
original purchaser only.
Chronograph Reset Instructions >>>
Chronograph Regular/Split Operation Instructions >>>