British v German rangefinders

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Byron Angel
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Re: British v German rangefinders

Postby Byron Angel » Sun Jul 03, 2011 1:01 am

Thorsten Wahl wrote:I pretty sure german optics of the WW1 timeline were somewhat better than their british counterparts.
I remember reading about a british offer via a neutral country regarding sniper optics for rubber.

Incidentally my textbook is from the end of the fifties. Hence it should include also summarised knowledge from the worldwars.



Hi Thorsten,

You might be recollecting the following. My best guess is that German optical glass may well have reached Great Britain via Sweden. Sweden, by virtue of its important iron ore trade with Germany, was probably the only nation with sufficient economic leverage to obtain such product from them.


quote ----------

The most important
pre-war producer had been Germany and, perhaps surprisingly, some supplies
of optical glass from there continued to be shipped to Britain throughout
the entire duration of the war. This remains something of a mystery, but
there is evidence in official statistics to indicate that glass was imported
from German ports of origin, albeit in decreasing quantities, from 1915 to
1918. The figures not only quantify the amounts landed, but also give some
categorisation of types. In 1915 there had been negotiations through
embassies in neutral Switzerland to secure deliveries from Germany of
particular optical munitions for the British forces. In principle, both
sides were willing to trade, Britain supplying rubber in exchange, and an
Act of Parliament was passed in 1916 to regulate, rather than prohibit,
trade with the Enemy. This proposed barter never came into effect, at least
in the form proposed. It must still be a matter of conjecture as to exactly
how the acquisition of German glass was organised, but it is apparent that
some considerable amounts were imported.

---------- unquote

NO GUNNERY WITHOUT GLASS - OPTICAL GLASS SUPPLY AND PRODUCTION PROBLEMS IN
BRITAIN AND THE USA, 1914 – 1918
By Stephen Sambrook

B

dunmunro
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Re: British v German rangefinders

Postby dunmunro » Sat Jul 16, 2011 9:32 pm

Here's an article by a USN officer discussing optics and stereo versus coincidence RFs, in March 1942:

http://www.sfu.ca/~dmunro/images/RF_USN.pdf

One has to remember that the USN did not have access to strip field coincidence RFs, since, AFAIK, they were only produced by Barr and Stroud, so his remarks about stereo and AA do not hold true for all types of coincidence RFs. He does discuss the problems of selection and training of stereo RF operators, however.

Paul L
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Re: British v German rangefinders

Postby Paul L » Fri Mar 16, 2012 4:56 am

It boggles the mind that Germany and Britain traded in such vital war related materials , while at the same time fighting against each other!!!

On the overall discussion I would point out the following. Unless you have independent body testing such equipment all you are going to get is reports that confirm the doctrinal POV of the host nation.... their equipment is better because blah blah blah. In terms of actual test results , to normalise the impact of human errors and preferences and a host of other variables & problems, you'd need to conduct scores and scores of such tests under pretty regulated conditions etc. Otherwize any error bars included have to be substantial obsurcuing any possiblity of real conclusions to be drawn. Military tests are generally not conducted in these mannors.

It looks like the Germans perfer long range engagements in marginal visiblity ,which is probably why they employ Sterioscopic range finders. It is intersting to also note that the development of German radar was also to solve that same problem and give even more advantage in such combat. They always seemed to have prefered quality over quanity when such issues emerged.

Likewize its not as surprising that the allies increasingly moved towards coincidence RF as these were easier to mass produce and most people could be trained on their usage ,where as Germans found that only 1 in 4 people had the vision sufficent use Sterioscopic RF effectively. If britian had problem to gain the needed glass quality this may also have influenced such efforts and the resultant findings of such military studies.
"Eine mal is kein mal"

garder
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Re: British v German rangefinders

Postby garder » Sat Mar 17, 2012 6:06 pm

Hi

Regarding the accuracy of german v. british rangefinders it could be interesting to compare what degre of error was allowed to pass the british and german rangefinder courses.

According to: Naval Staff Intelligence Department, German Gunnery Information Derived from the Interirogation of Prisoners of War German Gunnery Information Derived from the Interirogation of Prisoners of War, October 1918 the maximum error allowed for would-be rangetakers, in the german high seas fleet, at the end of the rangetakers course was 2 % i.e. 400 m. at 20.000 m. and 200 m. at 10.000 m.

Does anyone know what maximum errors where allowed at the end of the british rangetakers course?

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RF
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Re: British v German rangefinders

Postby RF » Sun Mar 18, 2012 7:38 pm

Byron Angel wrote: My best guess is that German optical glass may well have reached Great Britain via Sweden. Sweden, by virtue of its important iron ore trade with Germany, was probably the only nation with sufficient economic leverage to obtain such product from them.


Japan would also be a possible recipient through the Yanagi trade missions.

With respect to Sweden, I think there would be difficulty in getting it to Britain as German occupied territory gets in the way.
''Give me a Ping and one Ping only'' - Sean Connery.

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RF
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Re: British v German rangefinders

Postby RF » Sun Mar 18, 2012 7:44 pm

Byron Angel wrote:quote ----------

The most important
pre-war producer had been Germany and, perhaps surprisingly, some supplies
of optical glass from there continued to be shipped to Britain throughout
the entire duration of the war. This remains something of a mystery, but
there is evidence in official statistics to indicate that glass was imported
from German ports of origin, albeit in decreasing quantities, from 1915 to
1918. The figures not only quantify the amounts landed, but also give some
categorisation of types. In 1915 there had been negotiations through
embassies in neutral Switzerland to secure deliveries from Germany of
particular optical munitions for the British forces. In principle, both
sides were willing to trade, Britain supplying rubber in exchange, and an
Act of Parliament was passed in 1916 to regulate, rather than prohibit,
trade with the Enemy. This proposed barter never came into effect, at least
in the form proposed. It must still be a matter of conjecture as to exactly
how the acquisition of German glass was organised, but it is apparent that
some considerable amounts were imported.

---------- unquote

NO GUNNERY WITHOUT GLASS - OPTICAL GLASS SUPPLY AND PRODUCTION PROBLEMS IN
BRITAIN AND THE USA, 1914 – 1918
By Stephen Sambrook
B


I am very dubious about this claim of direct trading. Trading with the enemy was already a capital offence under the Treason Act.

More likely a sourcing from third party sources?
''Give me a Ping and one Ping only'' - Sean Connery.

Paul L
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Re: British v German rangefinders

Postby Paul L » Sun Mar 18, 2012 9:24 pm

RF wrote:
Byron Angel wrote: My best guess is that German optical glass may well have reached Great Britain via Sweden. Sweden, by virtue of its important iron ore trade with Germany, was probably the only nation with sufficient economic leverage to obtain such product from them.


Japan would also be a possible recipient through the Yanagi trade missions.

With respect to Sweden, I think there would be difficulty in getting it to Britain as German occupied territory gets in the way.



What Occupled territory? I thought all of Scandinavia was neutral during WW-I
"Eine mal is kein mal"

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RF
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Re: British v German rangefinders

Postby RF » Mon Mar 19, 2012 9:01 am

Sorry, I was reading this as WW2.

My mistake!
''Give me a Ping and one Ping only'' - Sean Connery.

tone
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Re: British v German rangefinders

Postby tone » Sat Sep 15, 2012 10:23 pm

I'll say from practical experience with a Barr and Stroud F.T. 37 that coincidence rangefinding (at least) would be extremely susceptible to motion of own ship and to vibration.

The simplest illustration in this is that a target is generally going to be on the beam, and your ship's roll is going to translate the greatest motion into pitch of your instrument. WIth a magnified view, you are going to see the object you're ranging upon moving up and down in an exaggerated manner while you attempt a cut. It's very difficult to do when holding an 80cm baselength instrument when there is no motion or vibration just to keep the vertical in view.

I also have a 60cm Zeiss stereo RF, but lack the know-how to use it (and probably also the acuity). I've not really used it.

I never understood why the Pollen/Cooke rangefinder stabilized the device in yaw. Pitch is where you'd most require this help, IMO

tone

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Re: British v German rangefinders

Postby tommy303 » Mon Sep 17, 2012 7:25 pm

I also have a 60cm Zeiss stereo RF, but lack the know-how to use it (and probably also the acuity). I've not really used it.


Does your reticule pattern have a series of posts and numbers which zig-zag across the field of vision?

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Re: British v German rangefinders

Postby dunmunro » Thu Dec 06, 2012 12:04 pm

tone wrote:I'll say from practical experience with a Barr and Stroud F.T. 37 that coincidence rangefinding (at least) would be extremely susceptible to motion of own ship and to vibration.

The simplest illustration in this is that a target is generally going to be on the beam, and your ship's roll is going to translate the greatest motion into pitch of your instrument. WIth a magnified view, you are going to see the object you're ranging upon moving up and down in an exaggerated manner while you attempt a cut. It's very difficult to do when holding an 80cm baselength instrument when there is no motion or vibration just to keep the vertical in view.

I also have a 60cm Zeiss stereo RF, but lack the know-how to use it (and probably also the acuity). I've not really used it.

I never understood why the Pollen/Cooke rangefinder stabilized the device in yaw. Pitch is where you'd most require this help, IMO

tone


A rather belated reply, but in WW2 RN HA and LA Directors, the RF was either power stabilized in roll or was stabilized manually by the DCT layer and trainer. Additionally many RN RFs including those in HA DCTs were duplex instruments, and one operator could (in theory) stabilize the RF while the other ranged.

Christian VII.
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Re: British v German rangefinders

Postby Christian VII. » Fri Sep 11, 2015 6:37 am

Wouldn't the German use of coated optics also constitute a significant advantage?

According to what I've read the coatings almost doubled the light gathering properties of each lens, allowing the Germans to make larger optical equipment with more lenses without any loss in clarity or brightness of image.

PS: Having visited the ordnance museum in Aalborg Denmark several times and played around with an actual original German Kriegsmarine bincular observation telescope. From the outside it looks pretty beaten up, and it also misses a lot of its original accessories, such a rubber eye pads and brow pad etc. However I have to say that once I looked through it I was blown away by the clarity and brightness of the optics. As percieved the image seemed even better than what I get with my expensive hunting scope from Leupold :shock:

Surprisingly, considering the overall state of the thing, it still visibly retains much of the original lens coating, although some of it has flaked away, and I suspect that this coating is part of the reason for the spectacular view. Definitely would urge anyone passing by to check it out. Hopefully it will stay in good shape being open to the public like that.

This is what it looks like (apologies for the horribly blurred image, the photo was originally of a Madsen AA gun in the foreground):
Image
Last edited by Christian VII. on Fri Sep 11, 2015 6:46 am, edited 1 time in total.

Christian VII.
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Re: British v German rangefinders

Postby Christian VII. » Fri Sep 11, 2015 6:42 am

A complete specimen:
Image
Image

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Re: British v German rangefinders

Postby dunmunro » Fri Sep 11, 2015 5:09 pm

Both the UK (Barr and Stroud) and USA ( Baush and Lomb) introduced coated optics in the late 1930s.

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Re: British v German rangefinders

Postby Christian VII. » Sat Sep 12, 2015 2:55 am

dunmunro wrote:Both the UK (Barr and Stroud) and USA ( Baush and Lomb) introduced coated optics in the late 1930s.


They were apparently not the same as the anti reflective coatings by Zeiss which were a closely guarded secret until the end of the war as far as I have read.

It's true that the use of lens coatings wasn't new (IIRC the Allies called it blooming), but the anti reflective coatings invented by Smakula at Zeiss in 1935 was a game changer. It provided an increase in the light transmitting properties of each lens of ~80%, which was a lot more than any previous lens coating.


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