Joe Gwinn wrote:
>Not surprisingly, the more expensive lens (55mm f/1.2) has almost all green
>reflections, and the same shade of green at that (showing tight process
>control), while the cheaper lens (50mm f/1.8) has all colors (looser process
>control) including white (uncoated surface?).
Joe:
"Process control" has nothing to do with the colors you are seeing, at
least not in the way you imply. Multicoated lenses typically have a lot
more colors of reflection than simple single coated lenses. While
traditionally a single coated lens could be identified by straw colored
reflections. However, I would guess that the green reflections you see
in your 55/1.2 are from single coatings that are peaked such that they
reflect green (although it could be a case of an early, simple
multicoating prescription).
My guess is that your 50/1.8 is multicoated, and to a much higher
standard than the 55/1.2.
As for process control in coating plants, it would be basically useless
to build a coating plant that performs as you imply. If you couldn't
control the coating thickness to the wavelength required, it would be
hard to know what results you would get. The coatings that resulted
would likely (very likely) end up doing more harm than good.
Cheers,
--Lee
< This message was delivered via the Olympus Mailing List >
< For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
< Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >
|