[rollei_list] Re: Identifying 2.8F models...the 3.5/75 six elements (again)
- From: "Peter K." <peterk727@xxxxxxxxx>
- To: rollei_list@xxxxxxxxxxxxx
- Date: Mon, 2 Jan 2006 15:02:06 -0800
OK Carlos, I have the Rollei 75 Years book, also written by Prochnow. On
pages 140 and 141 it stated the following with regard to the model F:
"Of course there were other improvements that had their share in the great
success of the "F" models. One of these was the new, six-element Planar 75mm
F3.5 lens which was introduced rather quietly with the third version of the
3.5F. Shortly after, Schneider followed with a 75mm Xenotar F3.5, likewise
made up of six elements. The new optical formulas served to meet the
performance data guaranteed to Rollei, which were difficult to attain with
only five element. Production costs remained unchanged. The 80mm F2.8 Planar
and Xenotar lenses did not have these problems and thus retained their five
elements."
So here is a book endorsed by Rollei and written by Prochnow where he claims
the 6-element version were done to improve the performance of the 3.5 models
and the interesting note is that it is clearly stated that PRODUCTION COSTS
REMAINED UNCHANGED.
This is why I stated this.
Peter K
On 1/2/06, Carlos Manuel Freaza <cmfreaza@xxxxxxxxxxxx> wrote:
>
> Excuse me Peter, I have the Rollei Report II and
> Prochnow does not write about resolving power problems
> for the five elements 3.5/75,and in his message to me,
> he insisted that the Planar and Xenotar six elements
> were cheaper to manufacture than the five elements and
> this was the only reason to provide the Rolleiflex
> with this six elements 3.5/75 Planar and Xenotar;
> Richard K.also suspected this economical reason before
> I received the message from Prochnow and the lens
> designer friend of Richard K also wrote about these
> economical reasons agreeing with Richard.
> If you see the second element for the five elements
> Planar 3.5/75 and the fourth element for the Xenotar
> 3.5/75, they are a thick glass piece, a divergent
> meniscus (negative lens); for the six elements version
> this piece or element was divided into two thinner
> pieces and cemented maintaining its condition of
> divergent meniscus and occupying the same place
> regardiong the original divergent meniscus, the other
> elements are identical for the five and six elements
> versions and then they are (the five and six elements)
> the same lens in practical use.
> I owned a 3.5E provided with a Planar five elements
> several years and it was an outstanding lens for
> 50x50cm enlargements.-
>
> All the best
> Carlos
> PS:Peter, if necessary, I have the question and the
> Prochnow's answer.-
> --- "Peter K." <peterk727@xxxxxxxxx> escribió:
>
> > Yes Carlos I know. In his book however, Prochnow
> > claimed, or used, the party
> > line that it was for resolving power. May actually
> > be a combination of the
> > two.
> >
> > Peter K
> >
> >
> > On 1/2/06, Carlos Manuel Freaza
> > <cmfreaza@xxxxxxxxxxxx> wrote:
> > >
> > > --- "Peter K." <peterk727@xxxxxxxxx> escribió:
> > > > >.... The 3.5 version of this
> > > > model also received a newly designed Planar lens
> > of
> > > > six elements, followed
> > > > by a new Schneider 3.5 Xenotar with six
> > elements.
> > > > This was allegedly to
> > > > improve the resolving power since F & H were of
> > the
> > > > opinion that the older
> > > > style 5-element 3.5 lenses did not live up to
> > > > expectations....
> > > > Peter K
> > >
> > > According Claus Prochnow Rollei Report II and a
> > > message he wrote me answering my specific question
> > > about it, the change for a Planar and Xenotar
> > 3.5/75
> > > from five elements into six elements had
> > economical
> > > reasons only, the Planar and Xenotar five elements
> > > 3.5/75 had a thick element very expensive to
> > > manufacture and then this element was converted
> > into
> > > two thinner elements without a real change for the
> > > lens general design, you can clearly see it
> > comparing
> > > both lenses five and six elements diagram .
> > > Prochnow writes in his book that the six elements
> > > Planar and Xenotar 3.5/75 were "cheaper" to
> > > manufacture "maintaining the lens quality" (in
> > other
> > > words, the five elements was at least equal
> > regarding
> > > quality).
> > > He also writes that the Planar and Xenotar 2.8/80
> > have
> > > not production costs problems and then they were
> > > maintained without changes.-
> > >
> > > All the best
> > > Carlos
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> >
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> >
> > --
> > Peter K
> > Ó¿Õ¬
> >
>
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--
Peter K
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