What are the grades of Optical Glass?

chip j · Nov 22, 2016

There's the lowest grade-no brilliance; the next one up (Series One, Sigma, some Tokins & Tamron)-some brilliane; then there's full brillance-Nikon & Canon; at the top is glow and sparkle-Leitz and Zeiss. At least that's been my experience. (w/older lenses)

onre · Nov 22, 2016

How do you measure this?

bernard_L · Nov 22, 2016

don't feed the troll...
see previous similar thread: (there was a url link here which no longer exists)

remarkable excerpt:

Seems like most of you here in Doltland are incapable of appreciating me--it's like casting pearls before swine.

chip j · Nov 22, 2016

My mighty semi-diffused condenser Durst Micromat 35mm enlarger w/a 50mm Componon reveals ALL things in terms of negative brilliance. All prints were made on Brovira grade 1 glossy (cause the Durst is contrasty) and unferrotyped.

onre · Nov 22, 2016

bernard_L said:
don't feed the troll...
see previous similar thread: (there was a url link here which no longer exists)

remarkable excerpt:

Nice.

kobaltus · Nov 22, 2016

Business or pleasure, who knows...

AgX · Nov 22, 2016

I never saw a lens glow. Likely I did not heat it up enough.

tedr1 · Nov 22, 2016

Those who were expecting a sincere topic might find interesting the catalog from Schott Glass which describes grades of optical glass

http://www.schott.com/d/advanced_op...al-glass-pocket-catalog-february-2016-row.pdf

ic-racer · Nov 22, 2016

Many of the top lens manufacturers make their own glass to their own specifications, rather than purchasing graded glass on the free market.

Michael Guzzi · Nov 22, 2016

tedr1 said:
Those who were expecting a sincere topic might find interesting the catalog from Schott Glass which describes grades of optical glass

http://www.schott.com/d/advanced_op...al-glass-pocket-catalog-february-2016-row.pdf

That's the kind of grading I was expecting when I read the title of this thread...

AgX · Nov 22, 2016

ic-racer said:
Many of the top lens manufacturers make their own glass to their own specifications, rather than purchasing graded glass on the free market.

How many have a glassworks of their own?

John Koehrer · Nov 22, 2016

^^Schneider, Minolta used to,........My mind just went blank. I mean normal.

DREW WILEY · Nov 22, 2016

Any phD's in optical engineering out there who can respond to such questions? This is like asking how many craters there are on the moon.

chip j · Nov 22, 2016

I would assume that there's nothing more serious than eyeballing a print or slide-that's what it all comes down to. Don't need a PhD for that (except an acuired PhD in doing so).

AgX · Nov 23, 2016

John Koehrer said:
^^Schneider, Minolta used to,........My mind just went blank. I mean normal.

Schneider never had own glassworks.

The only german lens manufacturer that had an own glassworks was Zeiss.
(And then strictly speaking only VEB Zeiss Jena. And they lost them with the end of the GDR.
The westgerman Zeis had got a glassworks as sister company, though in practice that would mean the same as "own".)

flavio81 · Nov 23, 2016

chip j said:
There's the lowest grade-no brilliance; the next one up (Series One, Sigma, some Tokins & Tamron)-some brilliane; then there's full brillance-Nikon & Canon; at the top is glow and sparkle-Leitz and Zeiss. At least that's been my experience. (w/older lenses)

I agree with you, glass glow/sparkle is measured in lumens/mJ and currently Leitz is using glass LaK9 exclusively at all elements, this expensive glass tops the sparkle rankings at 10.89 lumens per milijoule.

Nodda Duma · Nov 23, 2016

DREW WILEY said:
Any phD's in optical engineering out there who can respond to such questions? This is like asking how many craters there are on the moon.

I'll do you one even better than a Ph.D who usually won't have decades of working knowledge in lens design.

It's all in ISO 172.

Oh and MIL-PRF-13830.

Maybe 10110 and ASME Y14.18M too even tho the latter is "sort of" obsolete.

There's the moon for ya.

Schott's related Tech Pub and Ohara's website tell you what you'll really get.

But when it comes down to it, you get what you need. No more no less

flavio81 · Nov 23, 2016

Nodda Duma said:
I'll do you one even better than a Ph.D who usually won't have decades of working knowledge in lens design.

It's all in ISO 172.
Oh and MIL-PRF-13830.
Maybe 10110 and ASME Y14.18M too even tho the latter is "sort of" obsolete.

I agree, in particular ISO 172 sets the standard for measuring brilliance or "sparkle" (as it's known in the slang of optical designers) for optical glass, and sets the measure to be in lumens per millijoule, previously it was using non-standard units of measure.

Schott's BaSF8 glass is the choice of Zeiss for high-sparkle glass and during the cold war the supply went more expensive due to the use of depleted uranium and dilithium crystals for its manufacture; which requires also the use of soylent green as a catalyst. At 9.81 lumens/mJ, it is not as brilliant as the favored glass by Leitz, but BaSF8 is able to be easily made into aspheric shapes by molding, so it is favored by Zeiss.

Nodda Duma · Nov 23, 2016

flavio I think your info is old. The International Optical Design Committee of Designers Optical recently concluded that due to increased human activity the number needed to be revised to 10.87. They're still working on updating the units.

flavio81 · Nov 23, 2016

Nodda Duma said:
flavio I think your info is old. The International Optical Design Committee of Designers Optical recently concluded that due to increased human activity the number needed to be revised to 10.87. They're still working on updating the units.

Sorry Nodda Duma, i'm just an amateur at optical design!!

So did you review the report of the German Lens Designers associations, where the International Lens Identification Contest 2016 results was published? Mr. Gunther Schwarzweiss Farben from Dresden won the contest correctly identifying ALL Zeiss versus Leitz versus Canon versus Nikon lenses by just looking at 8x10" prints carefully made with a modified Durst enlarger using a dilithium crystal film holder!!

PS: For those asking, film used was Agfa Copex developed in AF-Caffenol, "AF" standing for African-coffee variety, not Agfa, by the way.

Nodda Duma · Nov 23, 2016

I received the article but wasn't able to do anything but look at the pictures. Surprisingly, the B&W photos were shown in color. Anyways, they printed the article on ultra high gloss paper and it was just too sparkly to read under any kind of lighting.

Dan Fromm · Nov 23, 2016

All this optical desine stuff is wonderful, but I needs real advice, and not about sines, removal of. The OP is a strong partisan of lenses made, and the more recently the better, by Leiss and Zeitz. Po' folks like me can't afford wonder lenses like theirs. Which inferior brands, such as Stigma, Cikon and Nanon, should we dare to buy, inferior beings that we are?

Nodda Duma · Nov 23, 2016

Dan when cost is a concern I recommend the D.F. "Mk 1 Eyeball And Pencil" Camera. For film suggest perhaps a paper pad or the back of an envelope.

If you can't afford the pencil or even the charcoal accessory, suggest you loiter around after a forest fire. Charcoal accessories are free for the taking.

Be advised that camera degrades with age. When that happens you can substitute a 3-yr old with an iPhone.

Marcelo Paniagua · Nov 23, 2016

Dan Fromm said:
All this optical desine stuff is wonderful, but I needs real advice, and not about sines, removal of. The OP is a strong partisan of lenses made, and the more recently the better, by Leiss and Zeitz. Po' folks like me can't afford wonder lenses like theirs. Which inferior brands, such as Stigma, Cikon and Nanon, should we dare to buy, inferior beings that we are?

Sigma I would say. They invest a lot on research and development and their Arts lens series is pretty good

bdial · Nov 23, 2016

I should check out one of those "MK 1 Eyeball and Pencil" cams.

What are the grades of Optical Glass?

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