References on the meanings of colored lens dots

[Whir-Click]

How about a thread for references on the colored lens dots that fuel so much speculation? No claims without citing sources, please.

A yellow dot indicates the use of synthetic thermosetting cement instead of Canada balsam for extreme temperatures per this Army Technical Manual, pages 9-7 and 9-8.

A red dot indicates a lens has been treated against fungus growth and corrosion per this Air Force Manual, page 110.

A purple dot indicates anti-reflection coating per this 1947 B&L ad in International Projectionist.

[Drew Wiley]

Are you expecting some kind of brand to brand standard convention about what such colors potentially mean? That's unlikely!

[Whir-Click]

No expectations, just a place to pool references.

[Drew Wiley]

Well, hopefully someone can still dig up a proper vintage Goerz brochure (red dot, gold dot, blue dot). My wife purged a lot of my old literature heap; and the web isn't much help. But there still seems to be plenty of users of these on this forum, who might have some kind of reference official enough for you.

[Merg Ross]

An old question and a few wild answers. Scroll down to CP Goerz for best answer re the Artar.

https://www.largeformatphotography.i...s-on-my-lenses

[Jody_S]

Huh. I thought all those dots or triangles meant they had been rejected by quality control, so I've been painting over them before re-selling any of my lenses.

[Drew Wiley]

Ha! Sometimes shady dealers have painted their own dots onto old Goerz lenses to counterfeit sell them at higher price! Hopefully you never painted over an authentic blue dot.

[Whir-Click]

Found one more: a white dot on the rear of a Wollensak Graphic Raptar f/4.5 indicates that the measured effective focal length is within a tighter specified tolerance than the + or - 2% acceptable for “catalog stock.”

The performance specifications I have for the different focal lengths of this lens name different E.F.L. tolerances, but the reference to the white dot and note at the end are identical to the example attached.

[Drew Wiley]

I just noticed that the last of the Dagors (the Kern 14 inch single-coat and then multi-coated, marketed by Schneider) BOTH have a gold dot. I'm sure it's just a cosmetic nod to prior Goerz marketing tradition, and otherwise meaningless. Nothing on or in the original boxes mentioned a thing about it.

[David Lindquist]

I have a copy of a one page sheet under the letter head "C.P. GOERZ AMERICAN OPTICAL COMPANY." Heading is "ANNOUNCING THE GOERZ "RED-DOT" ARTAR LENS"

It proceeds with "Our untiring efforts to ever improve the quality and precision of our lenses have resulted in the creation of a superior ARTAR lens, the GOERZ "RED-DOT" ARTAR. The advent of still finer grades and types of optical glasses combined with our ability to choose from the best available resulted in the improvement of a lens which has long been accepted by you and your colleagues as one of the finest on the world market. To distinguish this ARTAR lens from the old line ARTAR we have engraved a RED DOT on the front lens cell."

This sheet is not dated but is accompanied by a price list headed "Improved! The NEW "RED DOT SERIES" that is dated August 1, 1953.

Note that "plain" Artars were coated since at least 1951, reference is the 1951 C.P. Goerz American Optical Co. catalogue here: https://www.cameraeccentric.com/stat...fs/goerz_3.pdf

Page 4 of the PDF includes the statement "We furnish all our lenses with reflecting surfaces coated."

Note that the camera eccentric website is currently suffering from an "expired certificate". I got in the same way I got in to this forum before it was fixed.

David