In "the world of OM Systems" (Pangerl), the SC lens diagram is shown with
two cemented pairs. The second element (first of the first pair) is almost
parallel faced (but highly dished). It is this element which seems to have
been amalgamated into the second element of the revised formula. No details
of glass are given, but I assume that it was there for colour correction,
and the revision made it redundant. there were lots of new glasses around at
that time..
Within the limitations of the published diagrammes, there don't appear to be
any other optical changes, but somehow it got 3mm longer to match the
100/2.8.
Julian
----- Original Message -----
From: <plp@xxxxxxxx>
To: <olympus@xxxxxxxxxxxxxxx>
Sent: Monday, September 09, 2002 12:50 AM
Subject: Re: [OM] 85/2: 5/4 or 6/5
> >The original formulation was 6 elements/5 groups. The later
> >version replaced elements 2 and 3 (a cemented group) with a
> >single element, giving 5 elements/4 groups. The shape of the
> >single element appears to be identical with the double element
> >of the original version.
> >
> >Something's wrong here: Replacing a group or (parts of a group)
> >with a single element can never reduce the number of groups.
> >The result would rather be 5/5.
>
> I agree. That suggests that the original version was 6/4, then
> they swapped a cemented pair of elements for a single element,
> resulting in 5/4.
>
> Why would a lens designer use a cemented pair of elements in
> the first place? That sounds like a kludge to me, a last minute
> fix.
>
>
> Pete
>
>
>
>
>
>
>
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