[LargeFormat] wollensak lens color coded dots

[Michael Briggs]

On 06-Dec-2003 Richard Knoppow wrote:
>   This is one of the puzzles I've been trying to find an
> answer to for a long time. Similar dots appear on post-war
> Bausch & Lomb lenses.
> 

This one of the biggest puzzles to me about Aero-Ektars.  Some but not all of
the WWII and 1950's 7 and 12 inch Aero-Ektars have a yellow dot as part of the
rim data.  All of the Aero-Ektars are coated, so I don't think that the yellow
dot has anything to do with the coating of the lens.  The yellow dot must have
been done by the manufacturer since it is engraved just like the white
lettering.  I have seen lenses with a engraved dot that was not painted
differently than the black background paint, i.e., the rim was engraved for a
dot but the dot was never used.  The yellow dot must have meant something -- but
what?    Perhaps the practice started with lenses for the miltary.  Perhaps the
original meaning was particular to the military or to aerial lenses.  Perhaps
it means some test result or quality level.   Another wild guess -- yellow and
red filters are commonly used for aerial photography -- buy why mark the lens?

--Michael