Old Ultravid vs new Trinovid (1 Viewer)

[greekgeek]

@tenex I bet you are a real hoot to be around at parties.

I made a remark, not a claim. Which within the context of the thread, was clear to most. Including you, made obvious in your initial "question" and subsequent replies that reveals what seems to be some rather vast knowledge on the subject.

Even if it were unclear, surely it was cleared up by the other two posters. And yet you simply had to show us all how very right you are (even when you asked for sources, yet so far have provided precisely none of your own... but I digress)
Next you proceeded to, strangely, reference glass tech available decades before the relevant period for the subject of this thread, the Ultravids and the Trinovid HD. Completely out of context for the thread.

Here is something for you to consider. Next time you want to share some knowledge, why not do it straightforward and as part of polite conversation?

You know, right out of the gate you could explain the nuance of ED and how we are really referring to the a subset of FL ED. But that within the FL ED realm, it is absent in the early Ultravids while present in the Leica HD series.

There is a fine line between precision and pedantry.

 

[tenex]

@tenex I bet you are a real hoot to be around at parties.

Don't be such a jerk.

I made a remark, not a claim.

"I am impressed with the OG Ultravids. For a non ED binocular, ..." is obviously a claim that the UVs are a non-ED binocular. Why you're obliging me to repeat myself I can't imagine, as you don't seem to enjoy it.

Which within the context of the thread, was clear to most.

You have no way of knowing what is "clear to most", this is only a guess... that most people will have understood that you were misspeaking? Did you?

Including you, made obvious in your initial "question" and subsequent replies that reveals what seems to be some rather vast knowledge on the subject.

Thank you. Odd though, how that motivates you to insult me.

Even if it were unclear, surely it was cleared up by the other two posters.

Only because I asked the question.

(even when you asked for sources, yet so far have provided precisely none of your own... but I digress)

I made no claims that require sources. To the contrary, I made it quite clear that we don't know that Leica used ED glass previously, but we certainly don't know they didn't, as you claimed, and it seems highly unlikely. The burden of sources and proof was on you.

Next you proceeded to, strangely, reference glass tech available decades before the relevant period for the subject of this thread, the Ultravids and the Trinovid HD. Completely out of context for the thread.

What are you still misunderstanding here? Glass technology used in earlier (and still used in lesser) Leicas is precisely the context of the thread.

Here is something for you to consider. Next time you want to share some knowledge, why not do it straightforward and as part of polite conversation?

I did. I asked a question because I didn't want to be too quick to assume that you didn't know what you were talking about. As to manners, you're the one who started accusing me of "pedantry", and are now whining about the result.

There is a fine line between precision and pedantry.

And you get to determine it for me? It's been a while since someone like you came along, for whom ignore lists were made.

 

[greekgeek]

Don't be such a jerk.

"I am impressed with the OG Ultravids. For a non ED binocular, ..." is obviously an (incorrect) claim that the UVs are a non-ED binocular. Why you're obliging me to repeat myself I can't imagine, as you don't seem to enjoy it.

You have no way of knowing what is "clear to most", this is only a guess... that most people will have understood that you were misspeaking? Did you?

Thank you.

Only because I asked the question.

I made no claims that require citing sources. To the contrary, I made it quite clear that we don't know that Leica used ED glass previously, but we certainly don't know they didn't, as you claimed, and it seems highly unlikely. The burden of sources and proof was on you.

What is your problem? Glass technology used in earlier (and still used in lesser) Leicas is precisely the context of the thread.

I did. I asked a question because I didn't want to be too quick to assume that you didn't know what you were talking about. As to manners, you're the one who started babbling about "pedantry", and are now whining about the result.

And you get to determine it for me? It's been a while since someone like you came along, for whom ignore lists were made.

Happy trails then, pard'. Can't say as though I'll miss corresponding with you. I do hope you find some peace in your life.

 

[LarryO]

Tenex (post #17) states that
"ED glass" means "Extra low dispersion", a range of glass doped with lanthanides."

This is incorrect. "ED" glasses are, indeed, "extra-low dispersion" ones, but they are not generally lanthanum-containing glasses. As Ignatius (post #10) notes, they are in a group of fluorophosphate glasses, the best generally considered to be Ohara FPL-53 and FPL-55, Hoya FCD100, and,, at a somewhat lower level, Ohara FPL-51. Some Russian glasses are also in the class. Calcium Fluoride (CaF2) crystal, "fluorite," is regarded as the model material for 'ED" elements, but the fluorophosphate glasses listed are extremely close competitors, preferred for various production reasons.

As the name suggests, "ED" glasses are characterized by high "Abbe numbers," a measure of dispersion that, paradoxically is higher for lower-dispersion glasses. They also all display low "Relative Partial Dispersions."
When combined with "mating" elements of suitable other glasses, they permit very high correction of problematic color aberration. The best mating glasses are ones with almost equal Relative Partial Dispersion, but significantly different dispersion (lower Abbe numbers). The degree of color correction is given by the difference of Relative Partial Dispersion divided by the difference of Abbe Numbers of the glasses involved.

For a thorough discussion of these points, with definitions of the optical properties mentioned and a chart comparing the relevant properties of many optical glasses, see the following page (and surrounding ones) of Vladimir Sucek's excellent Web textbook on telescope optics at

REFRACTING TELESCOPE OBJECTIVE: SEMI-APO AND APO OBJECTIVES

Refracting objective: achromat and apochromat. Description, illustration, optical properties.

www.telescope-optics.net

Lanthanum oxides were introduced in optical glasses as a rare-earth additives mostly to increase refractive index, replacing the highly radioactive throrium oxides initially used for that purpose. A famous early example was the Leitz/Leica Summicron 50mm f/2 lens, with thorium-containing elements in early versions, eventually replaced by lanthanum-containing glasses formulated in Leit'z's own optical shop, then licensed to Schott.

Rare Earth Glass Leica Lenses: A Quick and Quirky Overview — LSI - Leica Society International

Yes, they were (and still are!) literally radioactive, but they incorporated elements made of thorium and lanthanum glass because of their unique optical properties By Jason Schneider By the late 1940s, the management at Leica knew they needed to come up with a superlative successor to the well-re

leicasocietyinternational.org

For those interested, I've attached below my effort to summarize the main points, and an abbreviated chart of relevant optical parameters for some key glasses, that I've posted in a telescope-related forum elsewhere. Glasses with "LA" in their names are lanthanum-containing ones.

Besides high refractive index, lanthanum glasses do have low dispersions, but not at all as "extremely low" as those of the "ED" glasses. Some of the lanthanum glasses appear to be candidates as mating elements for the ED glasses. As noted, the difference in dispersion (Abbe number) is desirable for high color correction.

The Leica brochure Included by John Roberts (post #15), while presumably providing an accurate summary of the components in various Ultravid versions, unfortunately also contains marketing misrepresentations such as
that "dispersion" is "light scattering" in the section on "Fluoride lenses."

Larry

technical summary and abbreviated chart of optical properties
-------------------------
Briefly, the aim is to select pairings with as small as possible a difference in relative partial dispersion values -- PF,e for correction over the visible spectrum and Pg,F for correction in the violet range -- along with as large as possible difference in the Abbe number, Vd." The Abbe number is a measure of dispersion, higher for lower-dispersion glasses.

Relative Secondary Spectrum (Color) Error (for visible spectrum)
∆f / f = ∆PF,e / ∆Vd
(f = system focal length)
where PF,e = (nF - ne) / (nF - nC),
Vd = (nd - 1) / (nF - nC),
and "nx" are the refractive indices of the glasses at the Faunhoffer spectral lines (x=F, d, e, C).

Notes in the chart refer to examples of commercial doublets and triplets or those among the examples provided by Sacek in his section 9.2, cited above, and associated section 9.2.1 .

 

[tenex]

As Ignatius (post #10) notes, they are in a group of fluorophosphate glasses...

I had the impression that earlier ED glass types were doped silicates, not yet fluorophosphates?

In any case the fact remains that while UVHDs first featured fluoride (CaF2), previous models surely had other forms of ED glass already.

 

[LarryO]

I had the impression that earlier ED glass types were doped silicates, not yet fluorophosphates?

Examples? Documentation?

In any case the fact remains that while UVHDs first featured fluoride (CaF2), previous models surely had other forms of ED glass already.

Ditto

It can be confusing to readers when a forum member considered to be expert and knowledgable represents "impressions" as established facts -- post #17: "ED glass" means "Extra low dispersion", a range of glass doped with lanthanides."

I am unaware of any glasses being considered as "ED" before the advent of the fluorophosphates. (CaF2 crystal "fluorite" is an exception, but not really a glass.) Nor do current manufacturer's charts, such as Ohara's, show any non-fluorophosphate glasses in the "ED" area (Vd > 80).

https://oharacorp.com/wp-content/uploads/2024/01/glass-chart-2024-01.pdf

If you have more than an "impression" about this, I would be interested in some actual examples.

If there were "ED" glasses in Ultravid versions, or other Leica binoculars, before the HD's, it would also be interesting to have examples of those.

Larry