Range Finding

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jdlenton

Full Member
Dec 14, 2004
3,002
7
46
Northampton
Over the weekend some of us were lucky enough to spend a few day paddling on the Thames thanks Rich
During our trip one of the things that came up was judging distance and how accurate some people were and thought they were!

i got to thinking could you buy a small device that was robust didn't need batteries and that you could sight through and get a distance reading? this lead onto me thinking could you fashion something when out and about that could help you judge distance?
now I've seen fairly complex mechanical range finders for gunners on ships but i want a better bushcraft version something maybe a middle ages sailor would have had
Having had a bit of a Google around and not found much here's the question.

Has any body got any ideas designs about non electronic basic hand held simple range finders
in the historical record or that can be bought or that could be made by hand out of materials that could be readily found or recycled in the great outdoors?

James
 

Buckshot

Mod
Mod
Jan 19, 2004
6,129
151
Oxford
I missed that conversation James - what was it about?

The only things I'm aware of are electronic devices.
I assume you're thinking of something you can use so you don't have to move from the spot where you're standing?

Mark
 

leon-1

Mod
Mod
jdlenton said:
Over the weekend some of us were lucky enough to spend a few day paddling on the Thames thanks Rich
During our trip one of the things that came up as judging distance and how accurate some people were and thought they were!

i got to thinking could you buy a small device that was robust didn't need batteries and that you could sight through and get a distance reading? this lead onto me thinking could you fashion something when out and about that could help you judge distance?
now I've seen fairly complex mechanical range finders for gunners on ships but i want a better bushcraft version something maybe a middle ages sailor would have had
Having had a bit of a Google around and not found much here's the question.

Has any body got any ideas designs about non electronic basic hand held simple range finders
in the historical record or that can be bought or that could be made by hand out of materials that could be readily found or recycled in the great outdoors?

James
Yes, carry a stick with notches on it, the notches reperesent the relevant height of specific items at a specific range.

For instance hold the stick out a arms length, check the notch for the height of an average person / fence post / telegraph pole at a hundred meters. the smaller the height the longer the range, in the forces you use graticule patterns in sites and binoculars to do the same thing.

For instance a graticule that has the height of 20 mils will be the same height as a person who is 2 meters tall in height at 100 meters.
 

ArkAngel

Native
May 16, 2006
1,201
22
47
North Yorkshire
i doubt if you could make one yourself but my rifle scope has a resonably accurate rangefinder on it. A focus dial on the front with pre set markings, when the items in focus read off the range.

I wonder if a small monocular could be adapted to do the same?
 

Eric_Methven

Bushcrafter (boy, I've got a lot to say!)
Apr 20, 2005
3,600
40
69
Durham City, County Durham
If you have a map and compass (and you should have if you are outdoors) you can take triangulation bearings to find range quite easily. All you need are two identifiable features you can see on a map.

Eric
 

Ahjno

Vice-Adminral
Admin
Aug 9, 2004
6,843
32
Rotterdam (NL)
www.bushcraftuk.com
leon-1 said:
That's Parallax IIRC.:)

I tend to find being able to relate the size of an object in the distance to the size of a given object up close works pretty well and it is a lot easier than working with lenses in the long run.
Unless you are only familiar with churches being big tall buildings ... :rolleyes: Than you can be about a 1000 meters off :eek: ... Taken that into account, our distance judgement is pretty good, isn't it? :approve: :D
 

moduser

Full Member
May 9, 2005
1,356
6
56
Farnborough, Hampshire
Hi James,

Before the advent of laser rangefinders, archers used a mechanical type similar to this
http://cgi.ebay.co.uk/COLEMAN-RANGE...305QQihZ004QQcategoryZ383QQrdZ1QQcmdZViewItem

Quicks Archery used to sell them but I can't find it on the web site.

Another alterative which like Leon's idea of knowing the size of a object is the new range of rifle sights have reticules which allow quite accurat range finding.

A good example is the Hawk Air Max SR

http://www.hawkeoptics.com/specialized_reticles/AirmaxSR/index.htm

Moduser
 

Stuart

Full Member
Sep 12, 2003
4,141
43
**********************
Use your thumb



Stretch your arm forward and extend your thumb, so that your thumbnail faces your eyes. Close one eye (A') and move your thumb so that, looking with your open eye (B'), you see your thumbnail covering the landmark A.

Then open the eye you had closed (A') and close the one (B') with which you looked before, without moving your thumb. It will now appear that your thumbnail has moved: it is no longer in front of landmark A, but in front of some other point at the same distance, marked as B in the drawing.

Estimate the true distance AB, by comparing it to the estimated heights of trees, widths of buildings, distances between power-line poles, lengths of cars etc. The distance to the landmark is 10 times the distance AB.

Why does this work? Because even though people vary in size, the proportions of the average human body are fairly constant, and for most people, the angle between the lines from the eyes (A',B') to the outstretched thumb is about 6°, close enough to the value 5.73° for which the ratio 1:10 was found in an earlier part of this section. That angle is the parallax of your thumb, viewed from your eyes. The triangle A'B'C has the same proportions as the much larger triangle ABC, and therefore, if the distance B'C to the thumb is 10 times the distance A'B' between the eyes, the distance AC to the far landmark is also 10 times the distance AB.

http://www-spof.gsfc.nasa.gov/stargaze/Sparalax.htm

http://www.vendian.org/mncharity/dir3/bodyruler_angle/
 

jdlenton

Full Member
Dec 14, 2004
3,002
7
46
Northampton
Buckshot said:
I missed that conversation James - what was it about?
Mark
It was toward the end of the first day when there was some debate on how far we'd traveled in the boats and Jed started to test myself and roving rich on our distance estimating skills

leon-1 said:
Yes, carry a stick with notches on it, the notches reperesent the relevant height of specific items at a specific range.
thats a nice simple idea we'll have to have a play at the moot

Eric_Methven said:
If you have a map and compass (and you should have if you are outdoors) you can take triangulation bearings to find range quite easily. All you need are two identifiable features you can see on a map.

Eric
I can already do this quite accurately and you are quite right but i fancy a simple sighting device that can accompany my navigation equipment for quick simple sight estimating of distance.

moduser said:
Before the advent of laser rangefinders, archers used a mechanical type similar to this
http://cgi.ebay.co.uk/COLEMAN-RANGE...1QQcmdZViewItem

Quicks Archery used to sell them but I can't find it on the web site.
Dave any chance of a picture of one of these sounds really interesting but evilbay is blocked here at school

Stuart as usual mate you've produced the goods how did i know you would have some good contributions

James
 

moduser

Full Member
May 9, 2005
1,356
6
56
Farnborough, Hampshire
James,

Via ebay you are probably only looking at a few pounds if your prepared to bide your time.

For example the Watameter one (example3) is currently running at £2.60 with 4.5hrs left to run.

David
 

mark a.

Settler
Jul 25, 2005
540
4
Surrey
I was thinking about camera rangefinders. I have an old Fed camera which cost a whole £10 from ebay, so could be used for calculating distance. Just adjust the lens until the 2 images line up on whatever object you're looking at, then read the distance off the lens scale.

The only problem with that is that it'll only be accurate for short distances. Anything beyond a certain distance (not sure, but maybe something like 20 metres) would just be essentially "infinity" according to the camera. So it will be unhelpful for long distances, which I'm guessing is what you'd actually want it for.