[rollei_list] OT:Ghostless Coating
- From: Carlos Manuel Freaza <cmfreaza@xxxxxxxxxxxx>
- To: rollei_list@xxxxxxxxxxxxx
- Date: Tue, 23 May 2006 00:56:59 +0000 (GMT)
I have found in one of the more complete independent
sites dedicated to Pentax K products the following
info:
"Ghostless Coating
In 1997 Pentax released the FA 43/1.9 Limited lens ?
the first lens to feature the newly-developed
ghostless coating. This coating formula is an
improvement over SMC, and like its name suggests, it
is extremely successful at eliminating ghost images.
If one believes the rumors, the new coating was
developed for an automated traffic-identification
system. It was ordered by the Japanese police who was
having problems identifying car license-plates at
night due to flare caused by the cars' headlights.
Since 1997 Pentax has applied ghostless coating only
on several "selected" lenses, which probably means
that its application process is more expensive than
that of SMC."
And about SMC:
"Super Multi-Coating
To combat the undesirable consequences of partial
reflection, scientists developed chemical coatings to
be applied to glass surfaces. These coatings increase
r, and in the case of Pentax's famous Super
Multi-Coating (SMC), r = 0.998! Performing the above
calculation for a lens with 10 groups, we get L =
0.96, or only 4% light loss...."
It would be interesting to know more about the
Ghostless coating, this is the URL:
http://www.bdimitrov.de/kmp/technology/SMC.html
All the best
Carlos
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