Archived posting to the Leica Users Group, 1999/02/13

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Subject: Re: [Leica] CDI tested 80/1.4 R
From: Alan Ball <AlanBall@csi.com>
Date: Sun, 14 Feb 1999 07:24:35 +0100

Dominique PELLISSIER wrote:
> The Summilux 80 has been tested by CI two times : in 1999 as Pascal has
> just reported and in 1987.
> In 1987 they wrote : "The performances of the Summilux, 75M or 80R, are
> comparable :they are moderate but, however, remarkable at full aperture,
> then are improving very greatly when stopping down".

Dominique,

It is also interesting to note that the '87 report added in the right
column for the 80R: QUOTE "...in absolute terms its performances do not
quite equal those of some of its competitors..." UNQUOTE. 

The '87 test concluded the test with a 3 star evaluation on optical
performances, just like this month's. But it also gave 3 stars for the
quality/price ratio (against 2 this month). 

So, regarding conclusions, the inconsistency seems quite minimal. It
must be reminded that CdI accepts the idea of modifying evaluations and
ratings through the years (otherwise a simple reprint of the 1st tests
of an unchanged lens would have been quite enough). 

In the '87 tests, the graphs for the 80R and the 75M show an advantage
to the 75M, which is confirmed by the LUG's own absolute testing
institute (aka Erwin), but which was not commented upon in the editor's
text, and did not alterate the 3-star rating, of the time. This had
puzzled me since then...

For the 80R, the graphs of '87 are exactly the same as in '99 for center
performance but seem to loose almost 1 'bar graph point' at each
aperture on the edges. 

I do not have the '98 75M test form, but I suspect the graphs at medium
apertures will be the same as in '87, which would have objectively
justified the 4th star in the performance rating of the time. Can you
check ? 

BTW, despite all of Erwin's efforts to differentiate his procedures from
CdI's, it seems that when a feeble mind such as mine comes to summarize
his conclusions (feeble minds like simple conclusions and little stars),
they tend to converge with CdI's... Which is reassuring for the latter,
I suppose.

Alan