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Author Topic: Optical Range finder - How do they work?  (Read 2409 times)

Martin [Admin]

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Optical Range finder - How do they work?
« on: August 26, 2007, 09:37:35 PM »


Hi all,

How do ships optical range finders work?
Anyone know a good web page?
Where can I go and play with a real one?

Martin.
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gribeauval

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Re: Optical Range finder - How do they work?
« Reply #1 on: August 26, 2007, 09:55:32 PM »


Hi all,

Where can I go and play with a real one?

Martin.


If you need to play with an optical range finder then pick up a FILM SLR camera and look through the viewfinder!!  ;D
Focus on the object you want to 'range in on' and read the distance on the markings on the lens!  ;) ;D ;D

Mike

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bigfella

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Re: Optical Range finder - How do they work?
« Reply #2 on: August 26, 2007, 10:05:41 PM »

Is it that simple??? I thought there would be Gyroscopes and Gonkulators and Widgets attached.
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Bryan Young

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Re: Optical Range finder - How do they work?
« Reply #3 on: August 26, 2007, 10:25:15 PM »


Hi all,

How do ships optical range finders work?
Anyone know a good web page?
Where can I go and play with a real one?

Martin.


All of my earlier cable repair ships were firred with Barr & Stroud units. These were either 6' or 8' long. The principle is quite simple.
Using the eyepiece, focus on one image and bring the other into alignment and then read off the scale (usually in yards). The longer the "base line" the more accurate the result. Simple trigonometry really. Do you want to make one for a model or do you just want to play with one?  If you just want to play then I suggest you ask or contact any RN or RFA ship to have a look. The modern ones do not have a baseline but work on the same principle and are used for station keeping   i.e. keep 1.000 yards astern of the ship ahead and/or 1.000 yards abeam of another. 1,000 yards is about the max you can get out of these little hand-held jobbies but with an 8 footer you can get a reasonably accurate distance up to horizon distance. Radar is all well and good and I suppose nowadays they can calculate the distance between a flies eye and its chuff, but the optical gizmo was a joy to use. Ask any old sub-mariner. Cheers. BY.
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malcolmfrary

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Re: Optical Range finder - How do they work?
« Reply #4 on: August 27, 2007, 12:55:54 AM »

Lie about your age and join the Sea Cadets? ;D
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tigertiger

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Re: Optical Range finder - How do they work?
« Reply #5 on: August 27, 2007, 03:36:16 AM »

you can usually get this kind of stuff as Army Surplus.

Try Silvermans. or other places for laser range finders.

They are like a pair of binoculars but you only look through one lens. The other lens as an IR (I think) laser. Put the cross on the object and read the range.
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Martin [Admin]

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Re: Optical Range finder - How do they work?
« Reply #6 on: August 27, 2007, 04:11:03 AM »



The Bismarck I'm building has over a dozen range finders  in one form or another and just wanted to read a technical article about them as I've heard all sorts of clever things about them.....

Someone lent me "Model Werft" (the French model magazine) and there is a great article in there - "3-m-Entfernungsmess-gerat Typ "3u"... looks great but is doesn't read French!  :-\


...if only I had taken French seriously at school!....  :embarrassed:


BTW: "Model Werft" is a great looking magazine. there an article in there about building the happy Hunter and one about "Galathee" submarine discussed here: - http://www.modelboatmayhem.co.uk/forum/index.php?topic=5636.msg54661#msg54661


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RickF

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Re: Optical Range finder - How do they work?
« Reply #7 on: August 27, 2007, 10:04:31 AM »

The inability to read French should not affect your enjoyment of "Model Werft", as I believe it is written in German!!!!

Rick
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chingdevil

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Re: Optical Range finder - How do they work?
« Reply #8 on: August 27, 2007, 10:50:32 AM »

No comment Rick, no comment. This guy is in charge of this forum, scary aint it ;D ;D ;D ;D ;D ;D ;D


Brian
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Martin [Admin]

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Re: Optical Range finder - How do they work?
« Reply #9 on: August 27, 2007, 12:04:40 PM »

All right, all right.... look at the time of the post.....

I wondered why Google translator was having such a hard time with it!  :embarrassed: :embarrassed: :embarrassed:
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HS93 (RIP)

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Re: Optical Range finder - How do they work?
« Reply #10 on: August 27, 2007, 12:07:34 PM »

You could always make a DAM BUSTERS type range finder two sticks two nails, oh and a couple of towers on a dam .

Peter
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Re: Optical Range finder - How do they work?
« Reply #11 on: August 27, 2007, 12:37:07 PM »

Mayhem, Sir,

You may find this site of use.
http://hnsa.org/doc/br224/part3.htm#par256

Regards etc.
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tobyker

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Re: Optical Range finder - How do they work?
« Reply #12 on: August 27, 2007, 03:10:56 PM »

Indeed but the way they actually work is that there is a mirror at the end of each arm and the images are focussed upon the eyepiece. The mirrors are linked so that they move in and out together and the linkage also drives the distance scale. So focus the image, read off the scale. My dad had a German artillery on that foled so you could also use it as a tench periscope. He took it off someone who had no further use for it a Salerno. Unfortunately he 'lent' it to someone 30 years ago.
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dreadnought72

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Re: Optical Range finder - How do they work?
« Reply #13 on: August 27, 2007, 04:57:04 PM »

As an addendum, once you're happy with the pivoting-mirrors idea, you might like to know how a distance, bearing, two speeds and finite torpedo or shell-speed can turn into an accurate target solution.

For great (but large!) demonstrations of how this was done in pre-electronic times, take a look at the videos here: http://www.dreadnoughtproject.org/tech/

The Dreyer Fire Control Table in particular. I'm amazed it worked.

Andy
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