Last updated: 23 March 2000

This is a "User Opinions" page where YOU can express YOUR opinions. Contributions are welcome of course.

Subject:	Catalog specs...
Sent:	Thursday, March 23, 2000 03:17:51
From:	User100995@aol.com
In early January I noted that Meade had incorrectly misrepresented  the
Secondary Mirror Obstruction as "(dia.;%)".  The on-line catalog and
printed catalogs state that this number is 9.6% for the 90 ETX and 125
ETX.  Actually 9.6% would be correct if it was a % of area.  I mentioned
this to you in an e-mail and you stated you had been unaware of this
misstatement in Meade catalogs.  I had talked to a Meade tech rep about
it and he said he could not comment, only John Piper could.  I wrote a
letter to John Piper concerning this in January but he did not reply.  I
told you what I had done and you asked that I let you know his response.
 Perhaps you could get a response from him.
   Here is the text of the letter:

Dear Mr. Piper:

I have been a satisfied owner of Meade products over the years.  I have
owned two 2080 SCTs and, more recently, the ten inch Starfinder
dobsonian.  I have been looking closely at the ETX 125.

However, this exercise has brought something to my attention that
concerns me.  In the specs for the ETX 125 on your website there is a
category "Secondary mirror obstruction (diam.;%)".  It lists this figure
as 9.6% for the ETX 125.  But, in fact, 9.6% is the AREA of the central
obstruction compared to the AREA of clear aperture, NOT the diameter. 
Checking through my Meade catalogs I note that this figure is always
defined as (diam.;%) for all Meade cassegrain products, rather than the
correct definition of AREA.

This may lead the prospective customer who does not check the math to a
false conclusion:  that the ratio of the diameter of the central
obstruction to the diameter of the clear aperture is far less than it
actually is.  Since the ratio of diameter to clear aperture is
considered a reliable indicator of contrast and that an optical system
with a ratio of less than 25% is very good and less than 15% to be
excellent, Meade's figures are very misleading on their spec charts. 
There is no generally accepted "benchmark" for the ratio of obstruction
"area" to clear aperture "area".

Are you aware of this misstatement in your catalogs and website?

As a regular Meade customer over the years, I would appreciate an
     Thank you, Sincerely,
        James Phelps"

Mike, can you get an answer from Meade?
Jim Phelps

Mike here: The "obstruction" size has been a topic of much discussion on my ETX site and elsewhere. There appear to be no incorrect answers; just depends upon how you measure things.

Added later:

First of all, maybe you didn't get my main point about what Meade has
printed in their catalogs.  My main point with the Meade
website/catalogs was not that there might be disagreements on how one
measures things, but that Meade prints that 9.6% is a percent of the
Diameter (this is how they have it "(diam.;%)").  Since the flared
baffle on the ETX measures 52mm which results in 39.5% diameter
obstruction.  So, the first thing Meade doesn't do is accurately state
the obstruction.  Meade prints that the obstruction is 27.9mm, but it
conveniently leaves out the baffling which is certainly an integral part
of the obstruction.  Then it calls it a percent of diameter, when in
reality it is , without the baffling, a percent of area.  Two different
concepts altogether when discussing the nature of circles.

So, my main point to Meade is that they have incorrectly printed the
facts.  What they have printed is just plain false.  Even if they didn't
think the baffling was part of the obstruction, then the % diameter of
the secondary mirror to clear aperture would be 31%.

Can you find out why they falsely print otherwise?  Can you understand
that if they instead printed that the 9.6% was listed as "(Area;%)"
instead of "(Diam.;%)" it would be more acurate?

End of today's update

Subject:	 ETX-90EC  after one year
Sent:	Monday, March 6, 2000 20:27:12
From:	cyberguy@prairie.lakes.com (Todd Larson)
It has been about a year since I last contributed to this site, so I
thought I would mention a few things that might be of interest to other
ETX users.  I have been using an ETX-90EC for over one year.  Because I
am an ETX owner, I read this site often and can appreciate the different
viewpoints concerning the ETX scopes.

I don't need to delve into the long list of design problems associated
with this scope.  Anyone who is an owner, or has been checking this site
for more than a few months, is already aware of them.  But you might ask
what do I think of this scope that I have been playing with for 13
months?  Here is my opinion.

The first ETX-90EC I received from Astronomics had an intermittent drive
problem with the declination axis. Sometimes when powering up, the
declination axis would slew for 15 degrees and stop.  Since then I have
noted several other users describing the same symptom.

I waited a few more weeks for the replacement ETX from Astronomics. 
Actually I was glad that I had to wait for the next batch, hoping that
Meade would have discovered and solved some of the early engineering and
production problems.  I wasn't thrilled with the second scope, but at
least it worked.  I decided I could live with the second scope, figuring
that I could easily end up with an even worse sample for my third

So how does the second scope perform?  The optics are good, no surprises
there.  The electronics in the mount and the AutoStar are fairly good. 
The software is usable.  I am still using version 1.0c and I will
continue to do so until Meade comes out with a release that actually
fixes more things than it breaks.  It doesn't appear that version 2.0h
will win me over.

And, surprising as it is, the GOTO actually does work.  If only the ETX
had a decent mount, the GOTO would work MUCH better.  Meade is still
going in circles in an attempt to overcome, through software, the ever
changing backlash in this mount (Meade recommends you retrain the drive
every few months).  The mount and motor drives are just awful.  Toy-like
is the best description.  High power image vibration is bad.  I have
already had the declination axis apart once and will soon take both axes
apart to try to minimize the ever worsening backlash and sticky motion. 
If you want to look at something scary, just disassemble that mount, or
at least look at the 'tune up' guide at the Scopetronics site.

I went on record here, one year ago, stating that I would have GLADLY
paid $200 more for a well designed, solid mount.  Can you say NexStar 5?
 Of course, even the NexStar mount has backlash.  But it is apparently
much more consistent, and the drive doesn't even have to be trained. 
Slap an AutoStar on a NexStar and then you might have something.  Oh,

Some of you might be wondering why I didn't buy an LX200.  I would have,
but the LX200 series is at least 7 years old.  And with the recent
rumors of big price cuts on the LX200 series, it appears that Meade may
soon be releasing a replacement series for the LX200.  Why buy an LX200
when it might be obsolete in 6 months?  I hope they do it right and
design a technologically advanced version of the LX200.  Please Meade,
don't come out with a cheap, low quality replacement for the LX200.  You
will truly be shooting yourself in the foot.

And for those of you asking about CCD imaging (not digital cameras) on
the ETX, don't waste your time and money.  I do not know what Meade has
in mind for that second Aux connector on the ETX control panel.  But if
they are thinking of CCD autoguiding (as some have suggested), I can't
even imagine an autoguider that could tame the slop in that mount. 
Maybe an ETX-200EC with a rock solid mount and precision motor drive? 
Complete with PEC and Autoguiding?  Then you could talk CCD imaging.

OK... enough of this.  I'm going outside to play with my ETX-90EC while
we are still in this fantastic warm spell.  Snow is forecast later in
the week.

Clear skies,

Todd Larson 

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