AUTOSTAR INFORMATION Last updated: 23 February 2007

Subject:	AutoStar Home Position Summary
Sent:	Friday, February 16, 2007 07:22:46
From:	Littell, Charles C CIV USAF 88 CG/SCCV (Charles.Littell@WPAFB.AF.MIL)
The summary below was gleaned from the AutoStar software imbedded help
files.  I ASSUME these are correct, please advise if this is not a good
assumption!   If I am correct, the summary should be useful on your
site.

Chas

============================

AUTOSTAR ALIGNMENT HOME POSITION SUMMARY:  AutoStar alignment may be
done in several different modes, and there are differing "Home Position"
requirements to position the telescope (in some cases, even the tripod)
before the alignment can begin.  If setting circle is needed, see the
manual instructions first to check or calibrate it.

AUTOMATIC ALT/AZ ALIGNMENT HOME POSITIONS  ("LNT Home Position" for LNT
sensor models only)
    1.  "Automatic Alt/Az Alignment" at initialization (from power-on
"Press 0 to align")
            Unlock horizontal, rotate CCW (as viewed from above) to hard
stop, re-lock.  
            Lock vertical in any position.
    2.  "Automatic Alt/Az Alignment" from Setup/Align/Automatic Alt/Az
            Same as 1. above.

ADVANCED ALT/AZ ALIGNMENT HOME POSITIONS  ("Alt/Az Home Position")
    3.  "Easy Alt/Az Alignment" from Setup/Align/Easy Alt/Az
            Unlock horizontal, rotate CCW to hard stop, then back CW
appx 1/4 turn until a fork arm is over control panel, re-lock.  
            Unlock vertical, tilt tube to level position ("0" on setting
circle), re-lock. 
            Rotate entire telescope, including tripod if used, to point
North.
    4.  "Two Star Alt/Az Alignment" from Setup/Align/TwoStar Alt/Az
            Same as 3. above.
    5.  "One Star Alt/Az Alignment" from Setup/Align/OneStar Alt/Az
            Same as 3. above.

ADVANCED POLAR (also called "EQUATORIAL") ALIGNMENT (Photographer's
best)  ("Polar Home Position")
--Change Setup/Telescope/Mount from Alt/Az to POLAR; don't forget to
return to Alt/Az as needed when done)
--Set tripod tilt plate to your local latiutude
--Mount telescope on tripod in correct orientation (see manual "High
Latitude Leg" illustration)
    6.  "Easy Polar Alignment" from Setup/Align/Easy Polar
            Unlock horizontal, rotate CCW to hard stop, then back CW
appx 1/4 turn until a fork arm is over control panel, re-lock.  
            Unlock vertical, rotate tube to 90 on setting circle,
re-lock.
            Rotate entire telescope, including tripod if used, to point
North (tube pointed towards Polaris).
    7.  "Two Star Polar Alignment" from Setup/Align/TwoStar Polar
            Same as 6. above.
    8.  "One Star Polar Alignment" from Setup/Align/OneStar Polar
            Same as 6. above. 

NOTES:

    Unlocking the clutches or moving the tripod will alter the pointing
alignment, and the scope will have to be re-aligned.

    The above information is from my Blue Tube ETX-125PE UHTC, and
should equally apply to the entire ETX AutoStar / ETX LNT AutoStar line.
The summary was compiled from the AutoStar software help files (Ver
43ed), which I find to be widely different from the (sometimes
unintelligible) paper manual.

Charles Littell, Dayton, OH, USA      Feb 2007

Subject:	re: AutoStar Home Position Summary 
Sent:	Tuesday, February 20, 2007 21:46:06
From:	richard seymour (rseymour@wolfenet.com)
That's a very nice, concise summary of the various alignments.

Unfortunately they're all missing (or should be prefaced by)
one teeny tiny detail:  the power panel should be on the -west-
side of the base in all cases in the northern hemisphere.

In the southern hemisphere, the power panel faces to the
west for Alt/Az, and to the east for Polar mounting.

Having the power panel to the west may not be critical
for Auto Align, but it doesn't hurt to practice a good habit.

The Meade manual for the ETX 90/105/125 -PE no longer -says-
(compared to the non-PE) to point the power panel west,
but on page 36 it talks about the "turn to put fork over
power panel", and in a "footnote" on page 37 it admits
that the accuracy of the alignment slews will depend upon
"...and how close to North the telescope
is pointed when setting the Home Position."

From that we can/must infer that the power panel should face west.

Some scopes, such as the LX90, don't -have- hard stops,
so you simply start them with the telescope pointing north
(or west, if trying for Auto Align).

have fun
--dick

And:

I have also read that a home position East of North is bad, at least in
this hemisphere--same idea apparently.  Mike might consider amending the
"Summary" posting.  I wish I had a comprehensive technical explanation
of this equipment.

Has anybody approached Meade with a proposal to properly write a manual
(or three)?  I'm the new guy here, but I cannot believe how poorly
documented this nice instrument is!  It seems like this is a MAJOR
marketplace error on Meade's part.

If anybody decides to approach Meade--seriously--please consider me as a
participant.  I am an accomplished technical writer, editor, layout
designer, and photographer, with a strong background in optical
engineering (20 years electro-optical R&D with the AF).

Meade might well invest some money (and merchandise) to correct this
situation.  One thought, Meade would also likely consider something like
an ad-card included with the manual promoting Mike's aftermarket
publications, in exchange for his input and support.  If the project
doesn't appeal to you, perhaps you can refer me to an English-speaking
Meade person in that realm or responsibility.

Chas

And:

>....  I wish I had a comprehensive technical explanation
> of this equipment.

Depending upon which/what you seek, much is available at Mike's
site, plus in his book.
(Un?)fortunately, there have been 3 editions of ETX, and each
revision of firmware changes -something- making existing
knowledge drift slightly obsolete.

> Has anybody approached Meade with a proposal to properly write a manual
> (or three)?  I'm the new guy here, but I cannot believe how poorly
> documented this nice instrument is!  It seems like this is a MAJOR
> marketplace error on Meade's part.  
> 
> If anybody decides to approach Meade--seriously--please consider me as a
> participant.  I am an accomplished technical writer, editor, layout
> designer, and photographer, with a strong background in optical
> engineering (20 years electro-optical R&D with the AF).  
> 
> Meade might well invest some money (and merchandise) to correct this
> situation.  One thought, Meade would also likely consider something like
> an ad-card included with the manual promoting Mike's aftermarket
> publications, in exchange for his input and support.  If the project
> doesn't appeal to you, perhaps you can refer me to an English-speaking
> Meade person in that realm or responsibility.

Mike knows the people in/at Meade far better than i do
(he's a 4M advisor, too).  If i were to guess, i'd start
with Scott Roberts ( scott.roberts@meade.com ), but i don't
know how receptive they'll be.

have fun
--dick

And:

Thanks for the input.  I'd like to see Meade provide a good manual, so
folks wouldn't be so lost without external research.  If such a project
develops, I would like to participate.

Technical questions like "What's the effective difference between
Training Gears and setting axis percentages?" and "does the software
compensate for offset between Polaris and the pole during alignment?",
among many others, lack definitive answers in my research.

My 125PE has more than paper problems.  I finally have clear skies, and
even having carefully tuned per all the fine recommendations on Mike's
site (including taking up backlash during gear training, etc.), I am
suffering dramatic "rubber band" problems in the Dec axis.  There must
just be too much mechanical slop, I will dig into the gears tonight and
see what I can tighten up.

Hopefully the Scopetronix mechanical disassembly guide will suffice as a
starting point.  As Dick points out, each design change has its own set
of evolutions, software and hardware.

Astronomy enthusiasts are smarter than the average bear, but it is
disappointing that such a fine product is plagued by such documentation
and quality control issues.

Chas

And more:

> Technical questions like "What's the effective difference between
> Training Gears and setting axis percentages?" 

see: http://www.weasner.com/etx/autostar/as_info.html

"Percentage" is the fraction of "Training" you want applied as a
quick-spin when the motor reverses.  My patch kits let you see/edit
the Training results.

>and "does the software
> compensate for offset between Polaris and the pole during alignment?",

Yes, oh, Ye of Little Faith.

> among many others, lack definitive answers in my research.
> 
> My 125PE has more than paper problems.  I finally have clear skies, and
> even having carefully tuned per all the fine recommendations on Mike's
> site (including taking up backlash during gear training, etc.), I am
> suffering dramatic "rubber band" problems in the Dec axis.  There must
> just be too much mechanical slop, I will dig into the gears tonight and
> see what I can tighten up.  

Play with percentage instead.  That's what it's there for.
"Adjust to taste" (i let mine be a bit laggy).
And remember that an Alt/Az scope imparts Alt motion to follow
RA ... my guess would be that you were looking at an east or
west target ... and that if you look at a due-south target, you wouldn't
see the rubberbanding *in "DEC"*.

> Hopefully the Scopetronix mechanical disassembly guide will suffice as a
> starting point.  As Dick points out, each design change has its own set
> of evolutions, software and hardware.
> 
> Astronomy enthusiasts are smarter than the average bear, but it is
> disappointing that such a fine product is plagued by such documentation
> and quality control issues.

Many people blame the hardware for issues which are really (i almost
said "easily", but sometimes it's not) tunable by the controls provided
in the software.  Meade designed a cheap-to-produce system with the
Autostar doing the work of making it perform accurately.
My used ETX90 arrived with over 3 degrees of Alt slop (grab barrel and lift).
It achieved decent GoTo's.  (correcting the plastic fork flexure
reduced the slop to 1 degree, and -helped- the accuracy, but the
Autostar had been doing a fairly decent job of overcoming it).
Your 125 has far better internal mechaical structrue than mine does.

have fun
--dick

And:

Thanks for the interesting info!  Great article linked, very thorough
test process, very logical.  I think people who think like I do are very
smart.

Yes, the "rubber band" effect last night was a west view, sagging more
than the 26mm EP FOV (whatever that is-?) after slewing nose down, only.
OTA is of course nose heavy, makes sense it would settle by the backlash
amount.  Sorry, I don't immediately follow the logic on your "Alt motion
to follow RA" reference.

I was pretty careful with my tuning, including setting percentages just
below high as possible without any initial 'jerk' in the direction of
slew, though some ~random motion (< 1/4 26mm EP FOV, opposite to
direction of RA slew typical) at start of slew seems impossible to tune
out.  I am convinced mechanical adjustment is appropriate.

Besides, tinkering is fun, right?  I have always been far better at
fixing pin ball machines than playing them.  If I find anything
dramatically different than the Scopetronix photos, I will try to get
some jpg's for Mike.  If I break anything, I will deny this conversation
ever took place.

Chas of Little (Littell?) Faith

And:

> Yes, the "rubber band" effect last night was a west view, sagging more
> than the 26mm EP FOV (whatever that is-?) after slewing nose down, only.
> OTA is of course nose heavy, makes sense it would settle by the backlash
> amount.  Sorry, I don't immediately follow the logic on your "Alt motion
> to follow RA" reference.

I would think that a nose-heavy situation would cause the scope
to -continue- downward, rather than move back up.
But your mechanical adjustments surely will help the scope's operation.

By the "Alt to follow RA", i was referring to the fact that the
lines of RA painted across the sky are parallel to the horizon
when facing south, but have a severe "up/down" vector when you
face east or west.

Thus the motor reversals caused by releasing a slew key (if you;d
been slewing eastward) would be driving the azimuth and altitude
motors differentially, and the altitude motor specificially
in a different direction (if at all), depending upon which way
you were pointing.
If facing east, the Alt motor has to run the OTA up when simply
tracking sidereal motion.  When facing west, it runs the OTA down
to follow sidereal motion.  Due south the altitude motor doesn't
run at all.  Thus the perceived rubberbanding effects can differ.

have fun
--dick

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