rangefinder question

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amytom
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rangefinder question

Post by amytom »

At the risk of sounding ignorent, stupid , or most likely both:

I just received a new pair of binoculars from Boater's World (on sale $89.00) with compass and rangefinder built in. They have nice optics by my stabdards and the compass in the view is a great feature. Problem is the instructions don't say anything about the rangefinder. I'm hoping someone here can educate me.

The rangefinder has graduated marks in the view both vertical and horizontal.There also appears to be a form of slide rule near the right side lens; the labels include: angle, object size, and distance. My best guess is that I am suppossed to estimate the size of the object and compare that with the angle on the retical to get the distance.

Any ideas?


Tom
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SecondWind
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Re: rangefinder question

Post by SecondWind »

Tom,

You have it exactly correct. If it helps, many of the charts list the heights of towers, lighthouses, bridges, etc.
Terry Green
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36040
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Cat Tales
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Re: rangefinder question

Post by Cat Tales »

In case you'd also like the formula to calculate range based on height: (Remember to add the height of the observer PLUS their height off the water)

d = 1.17 x Sq. Rt. of H + 1.17 x Sq. Rt. of h

d = visible distance
H = height of the object
h = height of the eye of the observer


Also, here is a table to approximate range:

HEIGHT - DISTANCE
Feet - Meters - NM
05 --- 1.50 --- 2.6
10 --- 3.00 --- 3.7
15 --- 4.60 --- 4.5
20 --- 6.10 --- 5.2
25 --- 7.60 --- 5.9
30 --- 9.10 --- 6.4
35 --- 10.7 --- 6.9
40 --- 12.2 --- 7.4
45 --- 13.7 --- 7.8
50 --- 15.2 --- 8.3
Chris & Kelly Haretos
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Boynton Beach, FL
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