Author Topic: Reckoning Distance:  (Read 1822 times)

MoonMan

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Reckoning Distance:
« on: September 20, 2013, 08:52:22 AM »
On p63 of the Book, there is a description of how to use special binoculars to find the Distance of an object, if one know its height or width [Real Size]
Distance equals Size times 1000 divided by the reading on the scale [Apparent Size].
 In this case,the Binoculars have been made so that the Apparent Distance, relative to the scale, is 1000.
So, using terms Real Distance [D]; Real Size {S}; Apparent Distance [d]; Apparent Size {s}, we have the Ratios D:S::d:s, this becomes D:: Sd:s, or D=Sd/s; thus Real Distance is in inverse proportion to Apparent Size.
If one has no special device for Range Finding. he may go primitive: for Apparent Distance [d] use the length from the eye to the scale that is held by the outstretched arm [usually 10 time the length of the thumb, or the distance between the eyes: see Stereoscopic Ranging p169]. Thus for the scale, hold up a Ruled Edge to the Distant Object, invert the figure as a fraction of the units[1/s], multiply by Real Size{S} & Apparent Distance[d]. The result will be the Real Distance [D].
NOTE: NO measurement is exact, especially with things that move.
Keeping Track of where Here is in relation to There.

MoonMan

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Re: Reckoning Distance:
« Reply #1 on: October 09, 2013, 09:13:25 AM »
here is another way to get there. The principle is the same.
http://tomchuk.com/misc/rf/
Keeping Track of where Here is in relation to There.

MoonMan

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Re: Reckoning Distance:
« Reply #2 on: October 09, 2013, 09:21:46 AM »
Keeping Track of where Here is in relation to There.

Angle of Repose

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Re: Reckoning Distance:
« Reply #3 on: January 29, 2014, 08:43:19 PM »
here is another way to get there. The principle is the same.
http://tomchuk.com/misc/rf/

Cool info, thanks for sharing.
"You can't get there from here"

MoonMan

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Re: Reckoning Distance:
« Reply #4 on: January 30, 2014, 12:09:23 PM »
My pleasure, Angle of Repose. A useful skill,whatever way one goes about.
Keeping Track of where Here is in relation to There.