Testing controversy not confined to English mags.

http://tinyurl.com/3jngd

I found this article and translated part of it. It appears testing
and conclusion controversy is not confined to Sky and Tel, Astronomy
alone.



"For me, this Nexstar 8 GPS is optically a good instrument, and with a
l/6 statement on the wave obtained with the test of Roddier, certainly
in the group of head of the optically successful SC which I already
had the occasion to test, all confused marks.

Until proof of the opposite, I controlled the same instrument as that
presented in the article of Sky and Espace. The sight checks presented
in this article and my impressions clearly reveal of the results and
an opinion relatively different from that of Sky and Espace. I thus
think that Ciel and Space judged well severely with twists, probably
in all good faith this Nexstar 8. I do not find for example a first
clearly fragmented ring of the spot diffraction as C&E shows it on
their image of the spot of diffraction obtained on their bench. On
this point, Nexstar 8 as all C8 have between the secondary mirror and
the 3 adjustable tangents a sufficiently thick plate + cork duffel not
to transmit on the optics of possible constraints by an excessive
tightening of the screws of collimation.

In addition the total absence of quantitative measurements on the side
of Sky and Espace does not make it possible to judge severity of their
comparison with a Newton of 200 mm which thus seems relatively
subjective... In the absence of quantitative test, it would have
better been to compare the tube of Nexstar with another tube of C8 of
recognized quality. On the other hand I have me also noted at the time
of my comparative observations, a lack of contrast of Nexstar 8
compared with the 200/800, but nothing unusual compared to what I
could see in other SC. It is perfectly normal that a Newton, with
moreover one better optical quality in general has the top on the
combinations Schmidt Cassegrain and on this Nexstar in particular.

For a long time the amateurs claim truths tests in a review of
astronomy, and Sky and Space answer this request rightly. One can only
be pleased some.

However, the difference between my conclusions, those of Patrick
Furrier, in conformity with the miennes, and those of Sky and Espace
should encourage them to re-examine their procedures of optical tests
seriously, especially when one has such an audience with respect to
the public...

With their artificial star, it would be easy to obtain
publishable images of star test on beaches defocalized as well as
Ronchi, which would give already a good quantitative estimate of the
instrument that they control. Of course, this new procedure must be
imperatively validated by the passage on this bench of test of an
instrument perfectly known standard for on the one hand being certain
of what they do and also to bring the proof of the validity of their
procedure of test in the event of dispute.

To know some more about the optical tests in general and to have the
definition of certain terms given in this article, here 3 sites which
can be interesting to consult: