6 x 30 Czech binoculars.

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David Frydman
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6 x 30 Czech binoculars.

Post by David Frydman »

Interesting day.
Managed to get to charity shop in nice sunshine 3/8 cumulus 20 C.
I normally avoid this charity shop as they are notorious for overpricing. Many items are more than new prices.
Saw a binocular case on middle shelf of glass working cabinet.
Examined the binoculars inside and although without my reading glasses saw they were coded WW2 glasses.
Looked into them and they looked good. didn't even bother to check collimation properly though they seemed roughly O.K. and noticed a price tag of £4 on the binoculars in the case.
Bought them.
They are from 1940 to 1944 about, uncoated. Made by Srb & Stys forerunners of Meopta Prague, Czech.
They are probably identical to the Zeiss lightweight 6 x 30s, and if anything they are better. Weight 385 gms. which is half the British equivalent.
The optics are spotless inside, no dust, no fungus. Externally there are no scratches except a tiny mark.
The collimation is perfect.
The two individual focus eyepieces are smooth, perhaps rotating too easily. Perfect condition bakelite type eyecups.
Centre hinge stiff but O.K.
What is remarkable is the optical quality for a 70 year old binocular, which is far better than modern chinese binoculars up to £200.
The reticle is perfect, usually they go yellow or deteriorate with age.
I have to try them on the stars, but they seem very fine terrestrially. Of course now cloudy.
The Swedish firm of Nife is related to this as it was run by two Czechs who escaped to Sweden. The Nife usually have the three Swedish crowns marked on them.

So an example of how binoculars should be made rather than the shoddy goods peddled nowadays, where the chances of getting a good binocular is about one in five, and even then the tolerances are worse than on these ancient binoculars. Of course the chinese binoculars are coated, but sometimes these coatings are so minimal as to be ineffective.

Comes with probably original strap.
The light alloy bridge is not perfect but far better than most Zeiss 6 x 30s I have examined. They are marked from fairly heavy use but are remarkable considering.

I will use them for astronomy even though the reticule can be a nuisance on the Moon.
But on this reticule the markings are very fine and should not intrude for general astronomy.

Regards, David
Lady Isabella
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Post by Lady Isabella »

David

I own several pairs of WW11 binoculars (German and British), and have found them
to be excellent. I much prefer to use them instead of the modern day stuff.

Your BMK marked binoculars will be solid performers, based on my experience of this type of
binocular. Do they contain the standard H/6400 reticle? and do they have any other markings
i.e. K.F, circle or blue triangle.

It is a good job that they are clean inside as they can be real pigs to take apart.
The screws used on the prism covers are very soft and easily strip, and the oculars can
be extremely difficult to remove.

Like you say they are very lightweight, yet their construction has stood the test of time.
All my German optics blc, bmj and bmk (as well as my British) give excellent views.

The only downside I have with them is the Human story behind them, I seem to remember
reading that the factories used slave and enforced labour. The German binoculars produced
towards the end of the War is easy to spot as much of them were sent straight out in the
ordnance Tan colour. Many people always thought that these Tan binoculars were made
for the Afrika Korps, however the African campaigns were long over by then, and I tend to be
suspicious of any Tan coloured binoculars that are said to have been used by the Afrika Korps.
David Frydman
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Post by David Frydman »

Thank you Isabella,
They are black colour.
they are marked bmk + then a colourless equilateral triangle with flat base.
It could be any colour has worn off, as the triangle seems colourless.
They have domed screws top and bottom 12 in all probably original.
The reticule markings are extremely fine, i.e. thin, marked 20 each side. It may be the standard 6400, which I have seen referenced but the outside is not marked 6400 as some Zeiss. This binocular is better than the Zeiss ones i have examined.
What is remarkable is how well they have stood the test of time.
It does upset me to think of the human cost of what was a dreadful time.
Let us hope it does not happen again.

I must admit I got some c. 1955 16x56 Hensoldt roof prisms from the same source and they outresolve any modern equivalent except the 20x60 Zeiss IS.
The Hensoldt are totally exceptional, light weight very wide field approx 69 degree apparent of an extremely high optical standard, which is better than the top current binoculars I have tested. and the price was so low as to be silly, including a beautiful case.

Regards, David
Lady Isabella
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Post by Lady Isabella »

David

Your reticle is indeed the Standard Feldstecher Strichplatte that was used in the 6x30 models.

The triangle on your pair would indicate that the binoculars were most likely made for temperate climate use.
For colder climate they usually had K.F. Initials, and for really cold climates (i.e. Eastern front) K.F. and coloured triangle.

I did read that for very hot climates they used a green triangle, but I have yet to see such a pair.
David Frydman
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Post by David Frydman »

Looking at the full Moon the image is good with quite good edge performance.
The field is around 8 degrees but the sky is not clear enough for me to measure exactly.
The binoculars need cleaning externally optics and body, but I have not had a chance yet.
The contrast is not high but should be a bit better on cleaning. The lack of coatings accounts for most of this.
There are ghosts but not too bad.
The resolution is excellent.

The reticle measures seem to indicate on the full Moon, presently about 30 arcminutes that 10 equals about 35 arcminutes and 20 70 arcminutes, with the small 5 measures about 17.5 arcminutes.
This seems to indicate 1 measure is about 3.5 arcminutes or approx. one part in a thousand.
So I think that the 20 indicates that if a 20 metre object filled this space the distance is 1000metres or a kilometre.

Am I correct?

Will try again with clear sky and after external cleaning.
The reticle is in amazingly as new condition.

Regards, David
David Frydman
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Post by David Frydman »

The field is 8.5 degrees but there does not seem to be a field stop. This is O.K. as it gives a respectable field but with an indeterminate edge.
I saw two moons of Jupiter this morning.
The 10x25 modern coated high quality Docter showed three bright moons in comparison.
So the 6x30 Czech binoculars could do with coating. This just about started with top Zeiss models at this time, but it would be ten years later that routine coating appeared on binoculars.
The image quality of the 6x30s is good, but 6x is a little low for general astronomy.

Regards, David
Lady Isabella
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Post by Lady Isabella »

David

I know that the H/6400 was a system that was re-fined by the Artillery. Some of the figures you
quote do ring a bell, maybe any ex-service person reading this might like to enlighten us.

Last night I took the following WW11 binoculars out to have a look around:
blc (Zeiss) 6x30 H/6400, Kershaw 6x30 and a pair of Carl Zeiss Jena Jenoptem 8x 30
with multi-coatings.

All three gave excellent images of the moon. I simply could not pick a winner, maybe the Jenoptem
just a had a very slight edge regarding contrast. The views with both WW11 army binoculars were identical.
The field of view was around 8 degrees. Resolution excellent.
Ghosting and internal reflections were again the same, interestingly the multi-coated Jenoptem
appeared to show the same level of internal reflections.

Looking at Jupiter, both army binoculars showed Ganymede, Europa and Callisto. The Jenoptem with
8x did make it easier to see the moons.

The binocular I enjoyed using the most was the blc 6x30 for the simple reason that they are so
lightweight. In comparison the Kershaw are like a lead weight. Why did the British think it so necessary
to make them so heavy? Was it simply that they could not get the materials?
The German pair is excellent in terms of optical and mechanical construction, and they have
stood the test of time and continue to give excellent views.
The Kershaw are also excellent and easily match their German counter-part, it's just the weight
issue that I don't get.

In terms of optical performance I cannot detect a difference between the pair.
David Frydman
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Post by David Frydman »

Dear Isabella,

I think my measurements indicate that one unit on the Czech binocular reticle equals 1 millirad or one thousandth of a radian, or a thousandth of 57.3 degrees.
Why they choose to mark 20 I don't know. What could be 20 metres long, perhaps a house. I don't think a tank was that long. I will check.

Here with awful light pollution I only saw 2 moons of Jupiter, but the 10x25 Docter showed three bright moons. I suppose in a dark place the 6x30 would show the three moons, but I am a bit uncomfortable with a 5mm exit pupil nowadays and prefer 4 or 3.75mm.

Assuming the O.Gs are f/4, i..e. 120mm focal length, the eyepieces will be 20mm. I think they must have held the tolerances of these to 1% even 1/2%. This would be to ensure the reticle was accurate to 1%.
I doubt that they had say three slightly different reticles to cope with variations in eyepiece focal lengths although this would be feasable.

Normally I find even the Russian 8x30 too small for astronomy here, and mainly use 10x25, 12x45 Soviet, 8x40 UWA or larger binoculars.

The Moon was very good in the 6x 30s.

One reason why the British did not use light alloys may be because, say the 8inch f/2.9 Dallmeyer standard 5inch square format lenses light alloy WW2 mounts are dreadful over time and just crumble away.
Maybe we did not have good light alloys.

The other Zeiss lightweight 6x30s I have have poorer bridges than these Czech ones and the light alloy is partly failing but they are still serviceable after 70 years.

Regards, David
David Frydman
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Joined: Mon Jan 18, 2010 9:25 am
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Post by David Frydman »

A tank of this era is about 6 to 8 metres long, so maybe buildings were on average 20 metres wide? Maybe these were used for standard measures?

Anyway the reticle is useful. It would show the changing size of the Moon, and also one could measure other sky angles.

Regards, David
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