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Re: [OM] Re: olympus-digest V2 #1820

Subject: Re: [OM] Re: olympus-digest V2 #1820
From: Richard Schaetzl <Richard.Schaetzl@xxxxxxxxxxxxxxxxxxxx>
Date: Sun, 03 Sep 2000 23:35:20 +0200
Hello,

Norma Foltz or Hank Hogan wrote:

> I think this is a case of Ultraviolet sensitivity of color film and
> I would guess that you did not use any type of UV absorbing filter
> over the Zuiko 180 mm lens.
> Ultraviolet can cause just the sort of effects that that you showed with
> those nice images of the brunette in the white top and khaki skirt.
> I don't think this is a case of chromatic abberation -- the focus of different
> wavelengths at different plane.

I was always sceptic about that UV theories, but you let me rethink 
that. An light source intensiv enough, like a spectacular highlight 
might emit enough UV light to cause this effect. I always wondered 
why people only observe an blue cast, "ordinary" chromatic 
aberrations would have produced red coloured fringes as well (as 
could have been seen in that horrible EOS lens).

> Single coated lenses transmit more ultraviolet light than multicoated lenses.
> Most of the time ultraviolet does not cause a problem but on bright sunny days
> or other bright illumiation ultraviolet effects show up.

The 180mm Zuiko has only 5 lens elements, much less UV absorbtion than
an zoom lens or an 180mm/2.0 Zuiko.
I like to add my 180mm Zuiko has a new front element, when I bought it, 
the front element was scratched. So maybe, this has a stronger UV 
eliminating effect.


Best regards

Richard



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