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Lens evolution or devolution?


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An important thought from a member of the YASHICA FORUM  -- reprinted with permission:

 

This is something that kind of snuck past me. Maybe it's because my status has changed from the pro side back to a hobbiest and I haven't kept up with industry news, or it hasn't been a topic that makers want to publicly shout about... the bottom line is that the optical glass used in most of the best vintage lenses - has not recently been or will no longer be produced. I don't mean to say that it couldn't still be made, it's simply that they've chosen or been required by law to no longer make glass with certain additives, and that in turn, means the death knell for them producing the vast majority of glass formulas in use prior to about 2011-2016.

On Nikon's primary site for all their imaging products, there's a short one sentence explanation to the question of "What is ECO glass?" on an article within the site. This single answer is the complete article: "Eco glass does not contain any lead or arsenic, so it is more environmentally friendly than standard glass that contains these elements." What isn't mentioned is that ECO glass is all they use, and the list of additives no longer used is a higher count than the two they refer to.

The Schott Glass Catalog (150 pages) lists 100+ optical glass types in current production, with a guesstimate that 60-ish % of it being their "N" glass products, which they now term as Eco-friendly. Their included statement on compliance spells out the details of additives no longer used for all chemical compositions (from page 41)...

"All optical materials in this catalog comply with the requirements of European Directive 2011/65/EU (RoHS II). They do not contain any mercury (Hg), chromium VI (CrVI), cadmium (Cd), flame retardants PBB and PBDE, Bis (2-ethylhexyl) phthalate (DEHP), Butyl benzyl phthalate (BBP), Dibutyl phthalate (DBP), or Diisobutyl phthalate (DIBP). “N” and “P” glass types comply with the maximum concentration value of 0.1% for lead specified in Annex II of RoHS II. Some classical glass types contain lead oxide to ensure the specific optical characteristics of these products. They are in compliance with RoHS due to exemption 13a documented in Annex III of RoHS II."

I totally understand the rationale behind environmentally friendly manufacturing and keeping harmful chemicals from leaching into the soil and contaminating human beings. I can't in any way suggest that it is or isn't a sound choice or a good decision to follow the practice - only that if you appreciate legacy photographic lenses and the 'character' they produce by virtue of their chemical properties, now might be a good time to acquire the best you can afford. They are unlikely to ever be duplicated again. Three-quarters of the glass types once used in making lenses are forever gone. 1

Get used to the sterile look on new lenses, since it won't be going away.

1. 'Schott' glass varieties went from 273, down to 20 types. Data taken from the charts available here: www.closeuphotography.com/printing-nikkor-95mm-test

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I dare argue that 'sterile look on new lenses' is not neccesarily due to the type of glass used but more due to the complex computational optical designs and vastly improved techniques of molding aspherical glass or grinding to a precision of 0.01 micron. The lack of optical defects in the best modern lenses is lusted after by some in a strive for optical perfection, yet dismissed by others as sterile and with a lack of character. To each their own.

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44 minutes ago, thebeardedgroundsman said:

So, buy up your decanters and wine glasses as well! - this could get expensive...

If you don't mind subjecting yourself to lead ingestion then yes, that's what you should do. The lead in crystal leaches into the liquids it holds, especially acidic ones like wine. There's a reason this stuff is starting to get banned...

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