Pentax R-200 Series Instruction Manual page 62

●Calculation formula when atmospheric refraction and earth curvature correction parameter
is set to "OFF":
S: Slope distance
α: Vertical angle from horizontal
K: Atmospheric refraction coefficient (0.14 or 0.2)
Re: Diameter of earth (6,370 km)
13.6 Distance Range
Generally speaking, the maximum range which can be measured varies considerably
depending on the atmospheric conditions. For this reason, the Specifications illustrate the
values for both Good and Normal weather conditions.
It is extremely difficult to judge when weather conditions are "Good" and when they are
"Normal".With this instrument, the conditions noted below are used to differentiate between
the two situations, (Good weather conditions for surveying are different from Normal weather
conditions, and in surveying situations, cloudy skies are considered more favorable than
sunny skies.)
Weather conditions for measurement ranges are based on the following standard values:
Normal: Visibility of approximately 20 km, with slight shimmer and moderatewind.
Good: Visibility of approximately 40 km, overcast, with no shimmer and moderate wind.
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