Stereoscopic rangefinder

Discussions on the equipment used by the Axis forces, apart from the things covered in the other sections. Hosted by Juha Tompuri
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Erik E
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Stereoscopic rangefinder

Post by Erik E » 12 Mar 2002 16:20

I`ll just have to try one more time:

Does anybody know how to use these hand held rangefinders?

Erik E

RF HONTS
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Erik

Post by RF HONTS » 12 Mar 2002 18:34

Sorry Erik, I have never used one.

Roger

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Erik E
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Post by Erik E » 13 Mar 2002 16:34

There must be someone here at this forum who has one of these!???
(or know someone)
Any sugestions on where to ask for help? I have tried allmost every forum on www! Very frustrating.......

Regards
Erik E

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Tiwaz
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Post by Tiwaz » 14 Mar 2002 17:54

I'll see if I can get something out of my father. I think he used to use one of those long time ago...

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Erik E
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Post by Erik E » 14 Mar 2002 20:04

That would be great! Just let me know if you need a detailed description of "my problem"

Erik E

TL
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Stereoscopic Rangefinder

Post by TL » 15 Mar 2002 17:40

Hi Erik!

During my military service in the Finnish Defence Force I came into contact with stereoscopic rangefinders of a sort. I served as the 1st radioman for an artillery/mortar fire control squad, one member of which functioned as a 'rangefinder'. Two different rangefinders were used, namely a laser rangefinder as well as a stereoscopic version, which happened to be the principal tool, because it did not require batteries and could not be detected by tanks etc., unlike the laser rangefinder.

To be able to use the stereo rangefinder, you had to have stereoscopic sight (in your eyes that is). People that were judged to be fit for the task, had to take a two-week course to learn how to use the equipment. The interesting thing was that some of the guys I knew that took the course, never really learned to use the thing properly. Then again I also saw once how a junior sergeant from my platoon grabbed a rangefinder (a piece of equipment he had never tried before, let alone received any training to use) and proceeded, more or less accurately, to measure distances from our position to the general target area.

How to use it, for me at least, is a bit hard to explain, but I'll try. First of all, all the rangefinders looked ancient, the rumour had it that they were from WWII, secondly, they were quite heavy probably because they were made out of metal (the optical stuff inside the tube may have also added to the weight). When you measured a distance with the thing, the view through was basically the same as through a weak set of binoculars, apart from the fact that it had a three-dimensional 'grid' (if you did not have stereoscopic sight, you only saw the thing two-dimensionally which was no good) that seemed to be 'a part' of the landscape. Basically, if you saw, say, a barn in the distance, the grid told you the distance as some parts of it seemed to be closer and some further away, 'in' the landscape that is...damn this hard to explain, I'm sure if you've ever seen one, you'd know what I'm on about. This stuff would be easier to understand with the help of a drawing...

Anyway, it's been a while (well over 3 years) since the last time I saw a stereoscopic rangefinder and as I never received any official training for its use, it's really hard to explain how it worked, especially in English. Maybe if you could ask some specific questions, I'd be able to do a better job...

In the meantime,

Cheers,

TL

TL
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A pic

Post by TL » 15 Mar 2002 18:54

Erik...

After a bit of browsing, I managed to find a picture of a stereoscopic rangefinder as I used to know it...I hope we're talking about the same thing. Well, here's the URL, I hope it works...

http://www.mil.fi/joukot/tykpr/tulenjohtval.html

(it's the one in the middle)

cheers,

TL

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Erik E
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Post by Erik E » 16 Mar 2002 18:30

Hello!

The photo is allmost like mine. Not 100% the same, but close.
They probably works the same?

my main problem is:

If I have placed the barn inside the "grid", how do I know the range?
There is this knob for range (200-10000M) But the image inside the grid doesn`t change no matter what distance I turn to.....

I understand your explaining problems, but thanks for trying

Erik E

TL
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Stereoscopic Rangefinder

Post by TL » 17 Mar 2002 15:57

Hello Erik,

Well, first of all you need to have stereoscopic sight to see the grid three-dimensionally and secondly, the calibrations of the rangefinder need to be customized to suit every user (I'm not too sure about how crucial this is in the end though).

As I said, it's been a while since the last time I looked through one of those things. I only remember the 'grid', but I don't seem to recall whether or not it had some sort of numbers to determine the distance. You just need to see the grid 'in (3D) perspective', so it has to look like the grid is going away from you, so to speak. A good (and hopefylly accurate) analogy would be that of the grid being a road. If you know the length and different distance(s) of the road, you can know the distance to certain points by or close to the road from the point where you're standing.

The thing is that you may not be able to use the rangefinder due the reasons of your eyesight or unsuitable settings...

Even if you are able to see the grid as you are supposed to, I'm afraid that I cannot remember how you see the distance; as I said, I was a radioman...that was enough to keep me occupied. I suggest that you just go somewhere and choose yourself a suitable fire control position and some points the distance to which are known to you and start 'measuring' and see whether you are able to work it out...

The rangefinder pictured on the site the URL to which I provided seemed to be manufactured by Zeiss, I think that the company is still in existence. Try to contact them to see whether they have manuals for the rangefinder tucked away somewhere... Also the Finnish army should have extensive info on the use of the stereoscopic rangefinder, but whether or not they are willing or able to share it is another question.

Anyway, as I already said, it may well be that you just don't 'have it', if that is the case the rangefinder is pretty much useless for you when it comes to measuring distances...

This is all I can do at the moment, if there's any further information you want, I'll be more than happy to try and help you.

cheers and good luck,

TL

ps. I did not take a very good lookat it, but this site seems to some info on 'stereoscopic vision' that might prove helpful:

http://www.vision3d.com/stereo.html

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Simon H
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Entfernungsmesser 34? Rangefinder

Post by Simon H » 23 Apr 2002 17:02

Sorry for butting in Erik, I guess you have a model 1934 "entfernungsmesser" - rangefinder. This was standard issue to the German Army during WW2 and so is probably the most common. I couldn't fathom out how to read off the range either. Has anyone heard of the Entfernungsmesser 3m. It's a larger scissors type rangefinder - I guess for use by Flak crews. It's too heavy to handle & would have originally fitted to a tripod. Any info appreciated.

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Erik E
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Post by Erik E » 23 Apr 2002 19:59

There were even larger ones used at coastal batteries. A few of them is still left here in Norway!I think they were about 7 meters long!


This one is called EM 38.
Image

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Simon H
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Rangefinder

Post by Simon H » 23 Apr 2002 22:24

:lol:
A bit too big for my lounge Erik!

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Post by Darrin » 25 Apr 2002 10:02

I once used tried some type of range finder that may of been stereoscopic. It was a long time ago and I only tried it as familizeration I had no training and it was not what I did normally and it happened years ago. You look through the binoculars and see two images and adj them towards each other. When they meet you have some type of dis/measument scale inside or outside of the binoculars. More likly then not I am wrong so be warned.

Xanthro
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Post by Xanthro » 01 May 2002 01:00

There are two methods of using a stereoscopic range finder.

The simplest version requires a known height of a target. This requires target indentification. You can actually use this method without having to resort to steroscopes too. Though they make it more accurate.

Without knowing the height to of the target, you are basically trianglating a position. As you know the distance between to base of the triangle, and by focusing the angle of the lens to bring both images into focus, you know the degree of two of the angles, it's a simple calculation to determine the length of the remaining sides. This in turn, can be used to calculate the distance from the center of the apparatus.

Example, using a 7 meter steroscope. You chose a target and align the two images. The two images now are in focus and overlap appearing to be one image. Let's assume the angle to bring this into focus is 80. So we know have two 80 degree angles, so we know the remaing angle is 20 degrees as a triangles angle always add up to 180. We can then divide the triangle into a right angle at the center of the steroscope. This would give us angles of 90, 80, 10 and a known side of 3.5 meters. A calculation can easily be done to get the length of the unknown sides which gives you the range. I'll have to remember the forumula.

The dividing of the steroscope isn't normally done as the distances compared to the base are so long that simply using the side is enough. Normally, the steroscopic equipment will calculate the range for you based on the above reasoning.

Personal training is important, because people have different steroscopic abilities. Some people have great difficulty in lining the images up, as they already see them lined up.

Xanthro

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Erik E
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Post by Erik E » 01 May 2002 12:34

Thanks alot!

A bit more advanced than I first thought........

EE

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