• Welcome to BirdForum, the internet's largest birding community with thousands of members from all over the world. The forums are dedicated to wild birds, birding, binoculars and equipment and all that goes with it.

    Please register for an account to take part in the discussions in the forum, post your pictures in the gallery and more.
ZEISS DTI thermal imaging cameras. For more discoveries at night, and during the day.

Leica glass (1 Viewer)

Agree, as I posted in another thread this new glass seems to have a whitish look to it, almost a slight film or like a false brightness, I can’t put my finger on it, but I’ve noticed it in most all newer Alphas from the big 3.
I do wonder how many owners of single-coated binoculars said the same when multi-coating came along?
Between my BN and HD+ 10x32s, ~15 years apart, I too can see the difference we're talking about, but I wouldn't think about it at all in normal use of either one. The HD+ seems a bit brighter in a real, not false way. I don't find the newer look "filmy" (and don't want to be encouraged to!); in fact there are subtle details I can see in the HD+ better than the BN, though I don't know whether that's directly related to glass type. What would the actual difference be here, in objective terms? It's hard for me to imagine, transmission curves being as flat as they are.
 
Hi,

that is correct, all the telescopes manufacturers mentioned buy their fluorite crystal elements finished from Canon Optron - so did Vixen.

LZOS has the capabilities for fluorite too but very rarely does actually use it in in instruments for the civilian market:


Zeiss Jena pioneered the use of CaF2 crystal independently from Takahashi with their APQ oiled triplet lenses (and found an ingenious solution for avoiding the problems with surface quality and coating of fluorite elements). Dr. Pudenz, one of the original APQ designers seems to be working with some german telescope shop to make a modern version of oiled fluorite triplet...

Astro Physics has in the past worked with fluorite (the original f5 Stowaway).

TEC makes oiled triplets with a fluorite element.

Joachim
Ah, yes. I forgot about Vixen, who are now back in the game with a 55 mm f/5,5 fluorite refractor.
According to Wikipedia, fluorite is or has been used in microscope objectives from Nikon, Olympus, Carl Zeiss and Leica.
Because of the small size of naturally occuring fluorite crystals without optical defects, this was also the first optical application.

John
 
As mentioned above, optics manufacturers purchase glass blanks from various glass makers. There are many glass types
and quality levels and grades.
Many of the top makers then grind those blanks to their specs. and apply the proprietary coatings they prefer to use.
There are many glass types at various price points, coatings are also much the same.

Jerry
 
For what the glass blanks used to produce optics look like, along with the lens production machinery, see the following from:
• late 1960’s, both blanks and then state-of-the-art lens production at Leitz,
from: https://www.birdforum.net/threads/a-visit-to-the-leitz-factory-in-the-late-1960’s.396429/

• 2017, lens production at Leica Portugal, see post #20 at: repair cost

• 2019, blanks at Meopta, from: Meopta Factory tour 2019 - Optics info


And going back one step, for a comprehensive article with photographs of glass production at Nikon’s Hikari factory,
see: Glass for geeks: An in-depth tour of Nikon’s Hikari Glass factory


John


p.s. And next generation technology: a 2019 image that was previously on Swarovski's Swarotec site; at Home
It shows the use of robotics and is labelled 'Automated prism manufacturing in 24/7 operation'.
 

Attachments

  • Leitz late 1960's.jpg
    Leitz late 1960's.jpg
    224.6 KB · Views: 28
  • Leica Portugal 2017.jpg
    Leica Portugal 2017.jpg
    224 KB · Views: 27
  • Meopta 2019.jpg
    Meopta 2019.jpg
    168.6 KB · Views: 30
  • Swarotec 2019.jpg
    Swarotec 2019.jpg
    223.6 KB · Views: 23
Last edited:
Natural crystal colourless Saphires or Amethysts were used by a family of spectacle glass makers in Ceylon, now Sri Lanka from about 1360 till about 1980.

The methods for grinding and polishing the lenses were handed down from father to son.

I don't know if the family still make lenses.

I cannot find the article I have from a professional optical journal.

The original tools for shaping the lenses was shown to the author of the article.
My opthalmologist confirmed the authenticity.

The date is known as the King of Ceylon asked the optician to make the lens.
The optician asked the King's age and brought back the finished lens a few days later.

It is thought that the trade was brought from India even earlier.

Horace Dall used natural gemstones to make world record numerical aperture microscope objectives.

The Visby lenses found in Gotland are about 1,000 years old.
They are made from rock crystal.
Some are aspheric, such as a 50mm example and give high resolution.
It seems that artisans were skilled at making lenses long ago.
One of the researches suggests that some lenses were part of a telescope.

The Nimrud lens is 3,000 years old, but not very good optically.
There is reference to an older similar lens 4,000 years old.

Regards,
B.
 
Last edited:
The optician asked the King's age and brought back the finished lens a few days later.
Not terribly precise, eh...?
The Visby lenses found in Gotland are about 1,000 years old.
They are made from rock crystal.
Some are aspheric, such as a 50mm example and give high resolution.
It seems that artisans were skilled at making lenses long ago.
One of the researches suggests that some lenses were part of a telescope.
The one plausible idea I read on that is that those lenses came by trade from Byzantium. Medieval Islamic science hadn't fallen as low as Europe's. But so much of this entertaining story in Wikipedia, BBC etc is misleading. The mathematical meaning of "aspheric" was unknown; there's absolutely zero evidence for or mention of a telescope back then, when astronomy couldn't even measure positions very precisely and didn't understand how that was a problem; and on and on. Could have, might have... this shows why archaeology is more quackery than science. Anyone who ever examined a drop of water could easily have got the idea to try to shape some kind of "lens", and maybe it's best left at that.
 
That Horace Dall chap must have made some absolutely cracking binoculars eh, given how often you drop his name...?
 
Last edited:
Horace made some binocular telescopes, but as far as I know no hand binoculars.

He did make binocular adapters for telescopes, which were widely copied commercially.

He invented the atmospheric dispersion corrector.

Dozens of beautiful pocket folding telescopes.

1/40th wave spherometer.

He single handed repaired all the Leitz microscopes in the U.K. from 1939 to 1945 fabricating new optics as necessary. Also other makes of microscopes.

He did make some wide angle stereo cameras that produced excellent stereo pairs.

Very early colour photographs.

He was far away the best optical person I have met.
The breadth of his knowledge was amazing.
In his job of hydrodynamics he was world known.
In a class of his own in Britain.

There were optical geniuses in other countries like Gauss and Fraunhofer.
Baker.
Da Vinci
Vaisala.

And of course Newton, but before my time.

B.
 
Tenex.

Babylonian astronomy and mathematics was advanced.
Their records of eclipses are used to this day to refine our knowledge.

Hipparchus over two thousand years ago was measuring stars and planets accurately, using earlier Babylonian observations

Tycho Brahe made accurate star catalogues without telescopes.

One does not need mathematics to figure an aspheric surface.
It can be done by hand and eye.

The pyramids and even Stonehenge are accurately aligned.

B.
 
Babylonian astronomy and mathematics was advanced.
Advanced, for its time... but not in accuracy of observation.
The pyramids and even Stonehenge are accurately aligned.
Enough for their purpose (if a tomb can be said to have a purpose).
One does not need mathematics to figure an aspheric surface.
It can be done by hand and eye.
But one doesn't really know what one is doing... nor can it be easily communicated.
Hipparchus over two thousand years ago was measuring stars and planets accurately, using earlier Babylonian observations
Accurately? No. Nor had they.
Their records of eclipses are used to this day to refine our knowledge.
Recording eclipses wasn't a matter of accuracy at all back then, with poor measurement of time as well.
Tycho Brahe made accurate star catalogues without telescopes.
Yes, he was the first to even see a greater need for accuracy, after centuries of error had accumulated in predictions based on the less accurate observations of Hipparchus et al. (And only his greater accuracy made possible Kepler's discovery of the ellipses.) I thought of going into that but was trying not to be long-winded. And no that didn't require a telescope, just better instruments and methods... but I didn't say it did. Anything Tycho did, Hipparchus could have... but didn't.

Are we actually disagreeing about something here? It certainly feels so, but I can't tell what.
 
Last edited:
Horace made some binocular telescopes, but as far as I know no hand binoculars.

He did make binocular adapters for telescopes, which were widely copied commercially.

He invented the atmospheric dispersion corrector.

Dozens of beautiful pocket folding telescopes.

1/40th wave spherometer.

He single handed repaired all the Leitz microscopes in the U.K. from 1939 to 1945 fabricating new optics as necessary. Also other makes of microscopes.

He did make some wide angle stereo cameras that produced excellent stereo pairs.

Very early colour photographs.

He was far away the best optical person I have met.
The breadth of his knowledge was amazing.
In his job of hydrodynamics he was world known.
In a class of his own in Britain.

There were optical geniuses in other countries like Gauss and Fraunhofer.
Baker.
Da Vinci
Vaisala.

And of course Newton, but before my time.

B.
I don't know whether you have the available time and energy, but you seem the person best able to write a biography of this outstanding individual.
From the little elements that you've casually dropped into these BF discussions, I come away with a sense of an absolutely protean figure in the sphere of optics. His folding 6" scope exemplifies the kind of minimalist design only a superior understanding makes possible.
As with others, such as Whittle or Turing, his full range of capabilities do not appear to have been at all recognized by TPTB.
Nevertheless, he deserves to be remembered.
 
Hi Tenex,

We are not in disagreement except for the notion that it was not know before 1600 that two different focal length lenses would produce an enlarged or diminished image.

Ptolemy described convex lenses. Greeks and Romans were using lenses made from jewels as vision aids.

There were thousands of spectacle lenses made in the 1300s and 1400s.

I just found a Nikon 5T close up lens. No idea where I got it, maybe with a Nikon telephoto lens.
It is multicoated and a cemented doublet.
Concave rear, convex front surfaces.
62mm filter thread.
The focal length is about 700mm.
Holding it in front of my eye at about 500mm distance I get a high class image magnified 2.1x or 2.2x.
There is no false colour.
It is 58mm clear aperture f/12.
I can read car number plates far in excess of my normal distance glasses.
The field is only about 5 degrees.

I tried using a 20mm Japanese Erfle eyepiece to get a 35x image but my arms aren't long enough.
I'll have to find a long tube.

In my room looking at a clock 10ft away the magnification is nearer 3x held at arms length.

It would indeed be surprising if nobody pre 1600 didn't experiment with lenses.

Incidentally, both the Babylonian and Mayan calendars are accurate.
Probably more accurate than our calendars, unless we add leap years.

Conic sections were known in Greek times, regarding aspherics.

Regards,
B.
 
Last edited:
Thank you edudiant.

I am not up to it at the moment but I hope it is O.K. to mention:

Horace Dall (1901-1986): An optical genius. Martin Mobberley.

I can only say that Horace is not well known because of his extreme modesty.
He was wonderful with individual enthusiasts and went at whatever level was required.
He did not take payment from fellow astronomers for his work.
He turned down awards and senior positions also, as he just wanted to do what he did best.

As to Whittle. He had to put up with idiots in charge of the Air Ministry.
The information was freely available and enabled the Me 262 to be such a good aircraft.
Luckily for us their engines were not reliable because of poor metals.

As to the gift of three Rolls Royce engines to the Soviets, who then made the great Mig 15, I have no words.
We gave the engines so the Soviets could shoot down our aircraft.

Then we gave the supersonic Miles M52 to the Americans, so they could go supersonic first.

It is very lucky for Britain that there are idiots in charge of many other nations.

Tommy Flowers is another, who should be well known for making the Colossus computer.
He was badly treated.

Regards,
B.
 
Thank you edudiant.

I am not up to it at the moment but I hope it is O.K. to mention:

Horace Dall (1901-1986): An optical genius. Martin Mobberley.

I can only say that Horace is not well known because of his extreme modesty.
He was wonderful with individual enthusiasts and went at whatever level was required.
He did not take payment from fellow astronomers for his work.
He turned down awards and senior positions also, as he just wanted to do what he did best.

As to Whittle. He had to put up with idiots in charge of the Air Ministry.
The information was freely available and enabled the Me 262 to be such a good aircraft.
Luckily for us their engines were not reliable because of poor metals.

As to the gift of three Rolls Royce engines to the Soviets, who then made the great Mig 15, I have no words.
We gave the engines so the Soviets could shoot down our aircraft.

Then we gave the supersonic Miles M52 to the Americans, so they could go supersonic first.

It is very lucky for Britain that there are idiots in charge of many other nations.

Tommy Flowers is another, who should be well known for making the Colossus computer.
He was badly treated.

Regards,
B.
Thank you,. Binastro, for pointing me to the Martin Mobberley tribute.
It gives a good glimpse of the man and his work, although without much technical depth.

Doing poorly by super contributors such as Whittle and Flowers (or Turing for that matter) appears to be a government tradition.
Petters' Miles M52 design however was not a contributor to the US supersonic program, it failed to be first to break the sound barrier because
Prof Wallis (of dam buster bomb fame) persuaded the air ministry that unmanned drones should be used to explore the flight envelope rather than to risk a pilot's life. That decision sucked all the urgency out of the effort, so the lead was lo0st.
 
I have a Hoya 10x50 Porroprism binocular in good condition that is well made and performs well and has a field of just over 7.5 degrees.

The binocular may have been made by Seiwa Optical but I wonder who made the glass?

B.
 
Pilkington Wikipedia makes interesting reading.

Also Asahi Glass Company.

When researching thorium glass the conversation immediately changed talking to glass companies.
They did not want to discuss this at all.

I wonder how British glass makers managed in WW2 with supplying optical glass for binoculars, lenses etc.
I know that there are tremendous variations in the quality of British lenses from this period, but partly may be due to heavy usage, stripping, cleaning etc.

Where did they get the raw material?

B.
 
Warning! This thread is more than 3 years ago old.
It's likely that no further discussion is required, in which case we recommend starting a new thread. If however you feel your response is required you can still do so.

Users who are viewing this thread

Back
Top