Telemeter - Seiko 7T12 Instructions Manual

TELEMETER

(for models with telemeter scale on the dial)
l The telemeter can provide a rough indication of the distance to the source of
light and sound.
l The telemeter indicates the distance from your location to an object that emits
both light and sound. For example, it can indicate the distance to the place
where lightning struck by measuring the time elapsed after you see a flash of
lightning until you hear the sound.
l A flash of lightning reaches you almost immediately while the sound travels
to you at a speed of 0.33 km/second. The distance to the source of the light
and sound can be calculated on the basis of this difference.
l The telemeter scale is graduated so that the sound travels at a speed of 1 km
in 3 seconds.*
*Under the condition of temperature of 20° C(68° F)
CAUTION
The telemeter provides only a rough indication of the distance to the place
where lightning struck, and therefore, the indication cannot be used as the
guideline to avoid the danger of lightning. It should also be noted that the
speed of the sound differs depending on the temperature of the atmosphere
where it travels.
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HOW TO USE THE TELEMETER
Before beginning, check that the stopwatch has been reset.
START
(Flash of light)
STOP
(Crash of thunder)
Approx. 3 km
* Please note that the stopwatch second hand moves in 1/5 second increments and does not always
point exactly to the graduations of the telemeter scale. The telemeter scale can be used only when
the measured time is less than 60 seconds.
1 Press button A to start
the stopwatch as soon as
you see the light.
2
W h e n y o u h e a r t h e
sound, press button A to
stop the stopwatch.
3 Read the telemeter scale
that the stopwatch second
hand points to.
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