Last updated: 19 June 2009

This page is for user comments and information specific to the Meade ETX-90RA (originally known as the "ETX Astro"). Comments on accessories and feedback items appropriate to other ETX, DSX, and DS models are posted on other pages. If you have any comments, suggestions, questions or answers to questions posed here, e-mail them to me for posting. Please use an appropriate Subject Line on your message per the Site Email Etiquette. Thanks. Remember, tips described on this site may invalidate the warranty on your telescope or accessories. Neither the submitter nor myself are responsible for any damage caused by using any contributed tips.

Subject:	ETX 90 to ETX 70 fork.
Sent:	Wednesday, June 17, 2009 20:42:47
From:	Mark Medlin (
I hope some one can give me advice on this.  Is it possible to take the
Optical tube from an ETX-90(without Autostar) and put it in the fork
assembly of an ETX-70(with Autostar).  I believe I am sufficiently
mechanically skilled enough to do it, I just don't know if it will fit.
Is it too big?  Is it too heavy? Or is it just a really stupid idea?

Mike here: See the article "Putting ETX-90 on ETX-70 forks" on the Helpful Information: Telescope Tech Tips page.


Thanks for the reply, that was very fast.
I'm still looking through all the useful information on your site,
apologies for asking dumb questions before reading all the available
MIke here: There are no dumb questions.
Subject:	I don't understand the ETX-90 RA mount - how does it work?
Sent:	Wednesday, June 17, 2009 15:45:45
From:	Philippe Sismondi (
Greetings. I don't know if this is an appropriate question to send. If
not, so sorry! I did post the question on the ETX forum
but seem not to have asked the question clearly enough to get a good
response. I also scanned your site, but cannot find the answer there,
though it may just be that I don't know where to look.

First, I am not personally involved in amateur astronomy. I am just
trying to help my Dad (77 years old and not technically adept) to use
his ETX-90 RA. He purchased it ten years ago, but has never used it. It
was damaged somehow early on by excessive heat. I sent it back to Meade
this spring and got it repaired. This may barely have been worth the
money it cost to repair, but Dad was very psychologically resistant to
buying a new ETX, since his original one was completely unused. The
telescope has only the tracking motor (no computer control), and the
original three little legs that fit into the base instead of a nice

Dad is longing to see the moon, Jupiter and Saturn. So I am trying to
get him set up to do so. I will only be visiting my parent for two more
weeks, so I am trying to get this done quickly, without doing the basic
reading that would no doubt provide the answer. If I can get Dad
started, he will be motivated to learn a bit at a time by reading and
maybe joining a club.

Anyway, here is my question.

If I understand the way the mount works, then once polar aligned on the
three little legs, it is NOT possible to view all areas of the sky by
using only the equatorial mount. Is that correct? Or have I missed

To be more specific, in the polar alignment position, the tube is angled
upward as far as it can go. The mount seems to stop it from angling any
farther away from the north horizon. So, for example, it would not be
possible to look at a star immediately "above" Polaris. If that is so,
how does one look at those areas of the sky without moving the whole
telescope and losing polar alignment?

If I am right about this, would some other setup (like mounting on a
tripod) alleviate the problem?

Thanks in advance if you are able to help out an eager retired professor
look at the objects of his celestial yearnings! And sorry I don't have
time to do the basic reading :-{

Philippe S.
Burlington, Ontario
Mike here: When you mount the ETX-90RA on the tripod legs (or any ETX when polar mounted on a tripod) adjusted for your latitude, the telescope tube will hit the base when trying to view objects at low declinations. The problem is more severe the closer you are to the equator. But the further north you are (higher latitudes) the less the problem will be, such that at the pole, the base is horizontal and there is no problem anymore. You should be able to view objects at higher declinations. The other side of the problem is the difficulty viewing objects high in the sky, especially through the straight finderscope. The alternative is to mount in Alt/Az mode. You lose automatic tracking of the sky motion but at least you'll be able to view objects that otherwise you wouldn't. You just have to manually move the telescope tube to track objects. At low magnifications that is not difficult. But at higher magnifications, it is trickier.


Thanks for taking time on this. That made me think...and realize that my
question was a bit stupid. What is really puzzling me is what to do
because of the fact that as the mount rotates to follow an object, the
eyepiece becomes awkward or impossible to access. However, I may still
have it wrong. See the attached sketch. Am I right that the eyepiece
must rotate around to such an impossible angle in such a case? How does
one look at stuff that way?


Mike here: There can be times when the eyepiece is on the bottom. Just move on to a different object if you can't get into a position to look through the eyepiece. At a different time of the year, the object will be better placed for viewing.


Well, there's the answer.

Thanks a million. I'll show my Dad your website. He'll enjoy all this.

- Phil -

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