As the coatings are applied to the lens elements while they are held
on a rotating platform in a partial vacuum chamber, I imagine it would
be hard to not have the coatings applied to both sides of each optic.
It is possible, however, that the cemented elements are already
together prior to those applications. The coatings are applied by
heating various chemicals to vapor within the chamber while the
elements are rotated. I don't know if the coatings are applied one
after another in the same session, or if the discs containing the
optical elements are removed to rest between applications.
Anybody?
On Jul 13, 2009, at 08:30 , Dario Bonazza wrote:
Brendan MacRae wrote:
Was SMC applied to both sides of lens elements?
Apparently, original SMC was only applied to air-to-glass surfaces.
That's because with the introduction of A-series lenses, Pentax
claimed that at that point all lens surfaces were SMC-coated. To me,
it looks just like a standardisation of lens-making process. I
expect no improvement and no problem from a standard smc "uselessly"
applied to glass-to glass surfaces too. Probably a marginal
advantage could come from a tuned coating, adapting glass elements
of different indexes.
Although never documented by Pentax, it is believed that smc
coatings changed over the years, as the different color reflections
often suggest. Sure some change occurred from M-series to A-series
and in other instances.
Joseph McAllister
[email protected]
“If I could tell the story in words, I wouldn’t need to lug a camera.”
–Lewis Hine
--
PDML Pentax-Discuss Mail List
[email protected]
http://pdml.net/mailman/listinfo/pdml_pdml.net
to UNSUBSCRIBE from the PDML, please visit the link directly above and follow
the directions.
