Last updated: 13 July 2004

Subject:	First optical check of new ETX-105
Sent:	Sunday, July 4, 2004 16:13:59
From:	James Eagle (
I purchased the ETX-105 to have a 4in. portable scope to use on camping
trips to the  Sierra and Rocky mountains.   I had thought that sitting
the ETX on a picnic table viewing the dark, mountain night sky would be
just about heaven.  And it would have been, too, had there not been
clouds and thundershowers almost every afternoon, with the clouds
generally lingering into the evening.  I had used the scope for 2 nights
before leaving on this trip, but was not confident of the optical
quality.   The seeing was not steady enough to really tell.   If the
optics were not sufficiently good, I'd return the telescope.  (I also
have a 4in. Vixen/Orion fluorite apochromatic refractor, which has
essentially perfect optics, I believe; but with the equitorial mount and
counter-weights, is not as portable as I wanted for traveling.)  In any
case, after 10 days of clouds, I finally had a clear night last Friday
(2 July 04).  We were camping at Donner CA State Park near Donner Pass
at just under 7000 ft.  The afternoon cumulus cleared shortly after
sunset at 8:30 pm, and by 9 I had Jupiter in the viewfinder.  (I did an 
Easy "faux-alignment" by immediately hitting "Enter" when the slewing to
the alignment stars was complete.  The sky was too bright to see either
Vega and Atair.  Then I did a Go-to Jupiter ... did not come very close
... but close enough to find it, center,  and "synchronize" on Jupiter
by holding down Enter.   Even though Jupiter was only about 30 deg.
elevation, it was a beautiful sight.  Ganymede, Io and Europa were
visible, with Ganymede looking bigger and whiter than Io.   There was
some detail visible in the two major cloud belts, suggestions of other
cloud belts, and a very noticeable darkening at both poles.  With
Jupiter at opposition and the seeing good, I've seen the Jovian moons as
tiny disks in my 4in apo, but this view was almost as good.   I then
slewed to Vega and the famous double-double Epsilon Lyrae, which was
almost overhead.  The view was essentially perfect!   Both doubles split
at 100x, but the view at 150x was textbook-perfect.  Four tiny Airy
disks, each with 1 or 2 shimmering diffraction rings.  I'm keeping this
scope!   Unfortunately, clouds reappeared at about 1030, but I had
accomplished by main mission ... testing the ETX-105 optically.  And it
passed with flying colors.

Mike here: Thanks for the report! By the way, SYNCing on the planets or the Moon is generally not a good idea. It will be OK for some nearby objects but will likely get worse the further you get from the planet/Moon. Of course, the same is true for SYNCing on stars but less error will creep in.

Return to the top of this page.

Go back to the User Observations page.

Go back to my ETX Home Page.

Copyright ©2004 Michael L. Weasner /
Submittals Copyright © 2004 by the Submitter