Steve
As far as I know nobody has ever compared the two here in ENTS. Brunton makes
top of the line compasses/clinometers for geology work. would thin they would
make good clinometers. The thing to check would be how easily the readings are
to take, how closely can you estimate the angle, and if you sight the same
point several times from the same position (sight, drop it down, sight again,
do you come up with the same readings.
You can test the accuracy of the clinometer calibration:
Ed Frank wrote (Sept 14, 2005)
http://www.nativetreesociety.org/measure/instrumentation/suunto_clinometer_testing.htm
You can test the level accuracy of a clinometer or instrument. Sight from a
marked height at some object- tree of pole at a distance. Have an assistant
mark the point on the distant object the clinometer or instrument says is
level. Move to that spot and sight back to your original position. If it
is perfectly accurate the backsight will be right on the point you shot from
originally. If it is reading high, then the angle it is off will be
under-reading by arc tan [1/2 (error)/distance]. If it is pointing lower
than the starting point, then it is reading high, calculations are the same.
In this way you can tell at least if the original level line is actually
level or not.
There is no reason to think that the Brunton would be calibration error would
be any different from that of the Suunto. But you can use this process above
to develop a correction factor if you want. The error in the clinometer is a
simple mechanical one relating to the weight placement on the dial. It is a
simple error that should be exactly the same amount in the same direction at
all angles, unlike systematic errors which increase over a range. However
unless the clinometer is really way off, several degrees, then the errors at
the bottom (slightly larger but shorter distances, ad the errors at the top
slight ly smaller but longer distances) tend to pretty much cancel out
John Eicholz wrote (Nov 6, 2003)
http://www.nativetreesociety.org/measure/instrumentation/calibration.htm
I think I can prove mathematically that the error in tree height that
results from each degree of clinometer error is approximately between
1.75% and 1.9% of the horizontal distance to the trunk...Because the
factor: (1/cos(@))*(Sin(@)-sin(@+e)) is nearly a constant! Its range is
a smooth progression from 1.74% at 0 degrees to 1.9% at 80 degrees.
Ed Frank
http://nature-web-network.blogspot.com/
http://primalforests.ning.com/
http://www.facebook.com/profile.php?ref=profile&id=709156957
----- Original Message -----
From: Steve Galehouse
To: [email protected]
Sent: Tuesday, January 05, 2010 11:09 PM
Subject: Re: [ENTS] Suunto vs. iPhone
I have, and have been using, a Brunton clinometer rather than a Suunto---any
appreciable differences in quality or accuracy?
Steve
http://nature-web-network.blogspot.com/
http://primalforests.ning.com/
http://www.facebook.com/profile.php?ref=profile&id=709156957--
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