| RD
1000 stuff and a surprise |
Robert
Leverett |
| Sep
30, 2005 12:51 PDT |
ENTS:
Yesterday PM, I tried the
magnifier on the RD 1000 again. Maybe I
thought that time would cure its ailment. I chose the Silver
Maple in my
yard as the target. At 4.6 feet above its base, the tree
measures 32.2
inches in diameter by the D-tape method. I have orange flagging
around
the trunk at this height. The reading from the RD 1000 was 35.0
inches
at 66 feet level distance from the trunk and 34.8 at 96 feet
away. BTW,
the 34.8 value is what reads on the scale. Readings above and
below the
34.8 would have been 33.6 and 36.0. It is all through built in
internal
tables. Consequently, there is no way to get a reading that
exactly
matches the measured diameter, even allowing for a tiny amount
of off
circular shape.
The magnifier produced a scale reading
that is high by 2.5 inches at
96 feet and 2.7 inches at 66 feet. I am hoping that the
magnifier will
produce scale readings that are off by a predictable amount, but
I'm not
counting on it. The magnifier is nice to use. It definitely
improves
visibility, but accuracy goes to hell in a hand basket.
I'm beginning to think that
the RD 1000 was rushed to production a
bit too soon. The internal scales appear to have been
constructed with
too many compromises taken and presently I can't figure out what
those
compromises are. As for my personal use of the RD 1000, I am
fairly
confident that I can make it a useful tool for volume measuring,
but
only after completing many tests and developing an extensive
calibration
chart will I become efficient. At present, I am reasonably satisfied
with the instrument at distances of 60 to 100 feet without the
magnifier
and at elevations 20 feet below to 20 feet above eye level,
maybe a
little wider range, but not much. At greater distances and steep
angles,
a lot more work must be done.
Bob
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