I dont't believe it is possible to learn much meaningful information
about relative lens performance from reading lens coatings, although tea
leaves might work for some. However, there is a theoretical
understanding error implicit in your comment. In fact, the more
effective the coating, the weaker (lower intensity) the reflections. A
perfect lens coating would transmit 1000f incoming light and reflect
nothing at all.
I am not trying to say the coatings on a 3.6 are better or worse than on
a 2.8, the lenses are far too different, designed so far apart in time
with different glasses, manufacturing techniques and computer design
aids available for a look at the coating reflections to mean anything.
Comparing SC and MC versions of the 24/2.8, 21/3.5, 50/1.8 and 50/1.4,
the most striking difference is not the color of the reflections,
although there are some differences, but the much lower brightness of
the reflections from the MC lenses.
A single lens coating is only completely effective at one wavelength at
any given angle of incidence. The effectiveness falls off with change in
wavelength and varies with angle of incidence. The 'coating color' you
see is the mixed color of the wavelengths at which the coating is least
effective. In SC lenses, the coating thickness was varied for different
surfaces partially to balance the transmittance across the visible
spectrum and maintain the color balance of the lens. That's why you see
several different colors of reflection on SC lenses.
Moose
Tim Chakravorty wrote:
I have looked at the front element coating and it doesn't appear to be too
strong either..there is only a mild hint of green/purple
when compared to its bigger cousin.
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