At 21:30 8/14/01, Dr. Sherpa wrote (in part):
I only told them that Zuiko lenses are compact, fast, good optics in general
and good construction. The nikon friends told me that had one big problem
Multi Coating...
What can I say ???
1. All a multi-coating does is broaden the improvment in light
transmission through the glass across the visible spectrum. In particular,
it improves the transmission at blue and red ends of the visible spectrum
to make it more even. A single-coating is centered (somewhere around
yellow-green) and works as well as a multi-coating mid-spectrum, but falls
off some in efficiency at the red and blue ends.
2. The first order effect of lens coatings is improved contrast with
better light transmission through the lens. Only under certain lighting
conditions with a bright light source forward of and illuminating the front
lens element does it become a flare issue. Unless you're using
super-wides, or have a strong proclivity for back-lighting, this does not
happen that often.
3. That first coating makes an enormous difference compared to zero
coating, especially on a prime lens with no more than 5 to 7 elements. If
you ever have a chance to handle pre-war vintage gear, much of it with only
4 or 5 element prime lenses, you can tell a huge difference.
4. Multi-coating only makes a very minor incremental improvement over a
single coating, especially on prime lenses. The efficacy of a single
coating is also affected by the refractive index of the glass used. Higher
index glass, as is often used in the better Zuiko's, decreases the gain
made over single coating by going to a multi-coating.
5. I'll stack my mint-minus, ca. 1954 **single-coated** 50mm f/1.5 Carl
Zeiss Sonnar with its 7 element, 3 group formulation that was created in
1932, against anything multi-coated they can muster from Can*n, Nik*n,
Pent*x, or Min*lta, in contrast, sheer resolving power, flatness of field,
flare control and absence of pincushion or barrel distortion. All I ask is
being able to run it at f/2 or tighter and to use a lens hood; they can do
the same. I'll even use it on a 50 year old rangefinder body. [Note that
the 5/4 formulation used for the 40mm f/2.8 Sonnar HFT for the Rollei 35 is
very, very similar, but not identical.]
6. Finally, it's not what you have, it's how you *use* it that
counts. When someone starts harping on how much better gear they have,
that's the time to shift it to who the better photographer is by asking to
compare portfolios of their best photographs. That's the bottom line.
Hope this helps understand it better. I wouldn't waste too much time
arguing the issue with them. Focus instead on making good photographs!
-- John
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