Techniques > Variations of Existing Techniques

Reckoning Distance:

(1/1)

MoonMan:
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.

MoonMan:
here is another way to get there. The principle is the same.
http://tomchuk.com/misc/rf/

MoonMan:
http://www.vendian.org/mncharity/dir3/anglecard/
this is a good one

Angle of Repose:

--- Quote from: MoonMan 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/

--- End quote ---

Cool info, thanks for sharing.

MoonMan:
My pleasure, Angle of Repose. A useful skill,whatever way one goes about.