Last updated: 10 November 2004

Subject:	High power observations with the ETX-90
Sent:	Friday, November 5, 2004 19:56:47
From:	chrisbrown4 (
Here's an observation report for you...
The Venus-Jupiter conjunction of November 5th inspired me to get up
extra-early to catch it...I prepared by setting my alarm, pre-timing my
coffee maker for 5:00am (dark roast!!), and setting up my ETX-90ra /
#884 tripod combo in the garage to ensure a "cool" scope when I awoke...

5:00am found ultra-clear, and super steady skies, however, I set my
telescope right next to the heater, which my wife had clicked-on in the
middle of the night! This meant that I would need a good hour to realize
perfect views, but it was worth the wait...

The conjunction was easy to frame at 39x in my 32mm Orion plossl (and my
42mm Ultima, for that matter!), and I noticed that two of Jupiters'
moons were stacked on one side, which was obvious in my ETX-90 even at
these low powers! Zooming in with my 10.5 Meade RG Ortho (119x)
confirmed the two stacked moons, and a shadow transit of Ganymede!!
Stepping up to 178.5x (Meade RG 7mm) brought more detail, a beautifuly
clear little black dot, and at least 4 bands!! As you can tell, I prefer
Orthoscopic style eyepieces for high-power viewing with my ETX-90. I
find that the views are razor-sharp, eye relief is generous, and I get
no "floaters", as experienced by my aging eyes when I use a barlow with
my ETX-90, at any power over 150x.

I then trained my scope on Saturn, and was rewarded by a beautiful view,
complete with an obvious cassini division, polar cap, and a clear ring
shadow at 208.3x (Optica B/C ortho, 6mm). Moments of good seeing
revealed a difference in shade between ring divisions!!

Now we all have read the Meade adds, where the professional astronomer
pushes the little ETX-90 over 300x on the moon, with no image breakdown,
but up to this point, I have been unable to avoid breakdown at these
powers, I even carry around a Meade 4mm RG ortho (312.5x) just in

This eyepiece has never held up on the gas giants, but on this morning,
trained on the 3rd-plus quarter moon, I was able to get a wonderful view
of the crater Purbach (I'm 90% sure of the crater's name) at 208x, with
sharp shadows and a little "straight wall"!! When pushed to 312.5x, 3 or
4 craterlets appeared, and I actually experienced very little image
breakdown, just the usual dimming!! To give credit where it's due, I
have found that 4mm circle-T Orthos (I have an old Celestron and a Meade
RG, which are nearly identical in image quality) to be fantastic
eyepieces, despite thier very small field stop, and I find them very
useful when conditions allow. By now, dawn was approaching, and I was
surprised to find the sky was now a pale blue! It was pitch-black just a
few moments earlier!!

I have owned this remarkable telescope for 4 years, and it has never
disappointed, me, or my other viewers, despite the fact that I have
never collimated it!!

It still shows 4 trap stars at the lowest possible magnification
(29.76x, 42mm Ultima), and Castor can still be split at 70x under good
conditions...(actually 69.44x, Orion 18mm Ortho!)

I stress the importance of favorable weather conditions to recreate this
fine performance, and as for me, I think I will be getting up early more

Chris Brown

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