Lenses getting sharper! every few years! is there a downside?

Started Jun 3, 2013 | Discussions thread
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Cytokine Contributing Member • Posts: 680
Lenses getting sharper! every few years! is there a downside?

I came across this publication from Schott Glass. (Zeiss is part of thi Schott group). Entitled:

Optical glass and glass ceramic historical aspects and recent developments: a Schott view

And it seems that lenses are becoming better and lighter because they are using higher refractive glass, but the downside is that Blue violet transmission could get worse, CMOS technology is already pretty bad at registering Blue violet. Here are a few quotes:

"Therefore high index glasses
(n > 1:8) ensure a high refractive power of the lens
and reduce the monochromatic aberrations. In addition
the high refractive power reduces the curvature
of the lens which in turn reduces the monochromatic
aberration as well as the weight of the lens. Unfortunately
the increased refractive index reduces the
transmission of the glass at about 400 nm (“blueviolet
transmission”) and below. This is a fundamental
relation since the refractive index rises only in the
vicinity of absorption lines, which also leads to higher
slopes, i.e., higher dispersion. There is no way
around this. High purity raw material and optimal
melting process can only avoid additional losses
and thus make the UV-edge steeper. However, for
thin lenses the blue-violet absorption may be low enough
to be acceptable"

"Camera software nowadays can compensate for
some color imperfections. However, current image
chips still have one major drawback: their weak sensitivity
in the blue range of the visible spectrum. This
requires that red and green channels have to be reduced
in intensity to fit to the weaker signal of the
blue channel."

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