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glass for lenses
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PostPosted: Mon May 11, 2020 2:56 pm    Post subject: glass for lenses Reply with quote
As all of us know Leica, Zeiss, Minolta, Nikon, etc produced their lenses using thier own glass

But when the brands whom traslated the manufacture of the equipmemt to other place (Leica to Canada, Rollei to Singapore, etc)

whose glass did they use?

Did Rollei use in Singapore the same glass for the lenses that used in German period?


PostPosted: Wed May 13, 2020 6:55 pm    Post subject: Reply with quote
They probably would have just used the same glass, I don't really see why not, it's just the cost of shipping. Otherwise they would have to redesign the lens for what glasses were available locally. Any substitutes would have to reach the same performance unless it's evidenced that each version of a lens performs differently although there can be other reasons for this such as general improvement or optimisation. A small state like Singapore would probably not have a sophisticated glass supply chain or the facilities to melt.
When Minolta assisted Samsung to start their camera business, they gave a licence to produce the Minolta products, but we know the products remained the same but now assembled in Korea, therefore they supplied the lenses.
Maybe Rollei wasn't even sending glass blanks to the Singapore facility but actually still supplying finished lens elements.
All you are really doing is changing the final destination of materials, of course each company pays for the logistics whether they make it in their own country or another one.
Nowadays there are third-parties that specialise in glassmaking and glass research like Hoya that can supply finished lenses or blanks to most major brands.


PostPosted: Wed May 13, 2020 7:52 pm    Post subject: Reply with quote
Sand Mines.

Here's some I explored in 1970s. https://www.ebparks.org/parks/black_diamond/ Most have been sealed since then. Somersville and Nortonville mines are said to have produced some of the purest silica sand for glassmaking, put out of business by less expensive Belgian Glass.

Did Zeiss use Belgian glass?


PostPosted: Fri May 15, 2020 12:28 pm    Post subject: Reply with quote
There may be some cases where alternate glass made to the same composition is possible, but in most cases changing to a different glass will change the function of the lens DRASTICALLY.
It's not just a matter of using a glass with the same refractive index, as refractive index varies with wavelength - this dispersion must also match and I'm sure there are many other parameters that are also vital important. Get things like this wrong & the perfect lens might suddenly have terrible chromatic aberration.


PostPosted: Fri May 15, 2020 1:35 pm    Post subject: Reply with quote
I asked the question cos Glatzel has designed the planar hft 50/1,8 made from 1970 with Seven different glasses, and one with lanthanum .

Cavina said that in 2003 some of the glasses used didn't figure un Schott catálogo. And he thought that thing was cos some of the glasses used are prohibited now.

Knowing that the Rollei Singapore production started to cut costs and being the planar hft made in Germany almost Equal in rendering than the one made in Singapore, say that both were made with Schott glasses?

Excuse my poor english, please


PostPosted: Fri May 15, 2020 4:39 pm    Post subject: Reply with quote
papasito wrote:
I asked the question cos Glatzel has designed the planar hft 50/1,8 made from 1970 with Seven different glasses, and one with lanthanum .

Cavina said that in 2003 some of the glasses used didn't figure un Schott catálogo. And he thought that thing was cos some of the glasses used are prohibited now.

Knowing that the Rollei Singapore production started to cut costs and being the planar hft made in Germany almost Equal in rendering than the one made in Singapore, say that both were made with Schott glasses?

Excuse my poor english, please


Your English is good, by the way. Smile
It is impossible for us to know the answer, and we can only speculate on what they might have done. If you have used an optical program before, there are at least a dozen different catalogues for glass types from all the corresponding suppliers in the world. Of course, they are all very close in performance or formulated to achieve the same goals, and by that I mean they will have similar but different indices of refraction and dispersion, and even the same number may possibly be reached by using different compositions in the glass of raw materials, like metals and oxides, and depending on the purity of the sand. As a glass type will be patented, then another manufacturer may not necessarily be able to copy a competitor's glass exactly. There are also the physical properties of the glass such as its transmission and softness.

Knowing how many years are between the production of the lens in Germany and then in Singapore, we could approach a more reasoned conclusion, but we would also need more historical data such as glass catalogues from each country.
I say if the performance of the lenses are indistinguishable, then why worry? Any differences would probably be within the normal manufacturing tolerance.
The establishment of Rollei Singapore is fairly well-documented, and I think for a facility of that size, it wouldn't surprise me now if they even did the lens grinding in this factory, as several articles seem to imply by stating that lenses were produced there: https://www.straitstimes.com/singapore/made-by-rollei-singapore-a-peek-into-history

However, that still does not help to answer the original question.

Personally, I think the glass blanks would be sent from Germany (or wherever they were produced) using the original raw materials and ground in Singapore using the same machinery. Why? Because then Rollei would not have to change anything about their logistics procedure or the production controls (glass melting is a highly automated and monitored process), and they would not have to redesign the lens and its coatings at all.
If the original design is the highest performance at the best price, then it does not make sense for there to be a cheaper option of materials that can produce the same result, sourced from somewhere in Asia - otherwise they would also do that for the Made in Germany model.
About 2 million Rollei 35 cameras were produced, so there would not be a significant saving between shipping the raw materials to Germany for combination and melting (as Rollei would probably have been locked into a contract with their original glass melter in Europe or somewhere else) and then sending the blanks onwards to Singapore, as opposed to shipping them from somewhere closer. It's only about $2000-4000 for a container load of cargo to be sent by shipping, today. If we assume that Rollei Singapore produced an average of 66,666 Rollei 35s per year (total production / 30 years), then realistically it is only a few containers per year to deliver the blanks.
To send the blanks from somewhere in Asia would be a saving of only a few thousand dollars per year, compared to the potential cost of maybe $500,000 to change all of the above processes and redesign the lens, and sign new contracts if at all possible under previous agreements with suppliers.

I hope this is not too much, and that it makes sense. Like 1 small


PostPosted: Fri May 15, 2020 6:07 pm    Post subject: Reply with quote
Teemō wrote:
.....Personally, I think the glass blanks would be sent from Germany (or wherever they were produced) using the original raw materials and ground in Singapore using the same machinery.


First. Thank you, very much. For your time, and for share you knowledge.

Second. Knowing all you have wrote here, I agree with your conclusion.
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