Date   

Re: Daytime...non-orthogonality

steppzimmr@...
 

In a message dated 7/5/00 12:31:47 PM Eastern Daylight Time,
myrocketcatos@... writes:

<< Peter, Can you briefly describe what you using on the 600EGTO and the
problem
you've encountered? I have to say, based on only one night's experience with
my 400GTO I can not imagine why anyone would be 'unhappy' with it.
>>

Hi Jeff, Yes, I am happy to discuss it. But I won't be very brief and I am
angry so you may not be sympathetic to my points. If so, I'll understand.
Here goes:

I bought the mount to use with a 9" Mak. I ordered the EGTO because Polaris
is not visible from my preferred site and I hoped the "goto" system would
help locate faint objects amidst the light pollution of Manhattan.

AP was very cooperative making a custom mounting plate for it. The plate
attached perfectly to the OTA.

The first night I tried using the two-star alignment is when I realized
something was wrong. No matter how carefully I followed directions I could
not achieve polar alignment. I spent hours and hours on this, wasting the
all too rare clear night on this effort. I even phoned AP and spoke with RC
himself. I found his suggestions baffling. Eliminating other factors, I
realized the problem must be orthogonality. I was very disappointed to learn
that only trial-and-error methods were used to solve the problem.

I was annoyed that after all the praise AP receives they provided no
standardized method or materials to help their customers with this problem.
All that precision, fit and finish, blah blah blah, and here I was expected
to cut up soda cans, punch out screw holes and spend hours using trial and
error to get the mount to do what they claimed it can do.

I know ETX-90 owners whose scopes did their goto thing right out of the box;
a COMPLETE system for less than half the price of my 600EGTO without its
extras: stainless steel counterweights, ash tripod, rings, etc.

I know, I know, you're probably thinking, "Stop whining, what a wimp!" Well,
I don't have time to fuss with this issue - I believe AP should provide
adequate documentation for overcoming lack of orthogonality. It is obviously
a major problem for many customers but they refuse to acknowledge it or find
a solution.
You see, I'm a guy who wants to buy a new item like a car or camera and not
have to "fix" it before I can use it. I want to drive off or start taking
photos, whatever the case may be.

I think AP should provide a system for achieving orthogonality and build it
right into the mount.

While planning to sell the Mak, I bought an AP 130 and it too is NOT
orthogonal to the mount. Wonderful...their own products aren't even
compatible.

That's not all: AP uses those cheap hard plastic knobs that cut your fingers
when making adjustments. Why not use a larger hard rubber knobs for a better
grip and more comfort. I know, I should go out and buy my own, right? Well,
I think it indicates a bad attitude toward customers.

OK, Jeff, I'm ready; you can start throwing the sarcastic remarks my way. I
have heard them all already. Or you can just shake your head at this raving
and get on with something more positive. Alternatively, if you have a
systematic method that works. I am very interested.

Best wishes to you anyway and clear and steady skies always,

Peter


Re: Daytime...non-orthogonality

steppzimmr@...
 

Michael,

Before I even finish reading your procedure and Derek's thoughts, let me
thank you and say that for the first time since my AP 600EGTO arrived I am
once again excited about using it. It's a beautiful day after the 4th here,
I am off work and can try your procedure in preparation for our first clear
night forecast available to me in months.

I'll let you know what happens, but thanks for giving me HOPE at least,

Peter in Manhattan


Re: Fw: Daytime procedure for correcting non-orthogonality

Derek Wong <dawong@...>
 

Mike:

Thank for posting this, it makes a lot of sense. I have gathered a few
more thoughts on this and would like Mike and everyone to check this as
my geometry is suspect, and I apologize in advance for the long
rambling! By the way there is a way to check orthogonality at night in
Roland's method in message #10 of this group.

When you do this daytime alignment there are two errors:

"Mount error" is the amount of error in alignment of the mount. At
night, this would correspond to your deviation from perfect polar
alignment. In the daytime, this is the deviation of the mount axis from
your alignment object. "Alignment object" is a distant object of your
choice.

"Scope error" is the amount of deviation of the optical axis of the
scope to the mount axis, due to a variety of factors including mount
hardware, accessories like diagonals, collimation, etc.

*****

Mike's method is very similar to the alignment of the polar scope. In
fact, if you have a polar scope then the task is MUCH easier:

--Align the mount to the alignment object using the polar scope with the
telescope in place, reducing the mount error to close to zero. Of
course, make sure the polar scope itself is aligned with the mount!

--Look through the telescope without a diagonal using a reticle
eyepiece, move the scope in RA. As Mike said, in an ideal situation the
center of the eyepiece should stay fixed on the alignment object. If
there is an orthogonality problem with the scope the center of the
eyepiece will rotate around the alignment object in a circle. Shimming
the scope will reduce this scope error to zero.

*****

Without a polar scope, I can see where this method could get
frustrating. In this case there will be mount error and scope error,
and you have to first reduce the mount error then do the fix above.

With both kinds of error, I am guessing that the center of the eyepiece
will traverse some sort of ellipse relative to the fixed alignment
object. If you rotate the RA axis until the distance from the eyepiece
center to the alignment object is maximum, then the mount error and
scope error are additive. At this point you can correct the mount by
moving the alt-az screws a small amount so that the eyepiece center
moves a little toward the alignment object. Basically, you are trying
to make the ellipse a circle, and there is some guesswork involved.

Unless your scope is smaller than a Stowaway you will not be able to
rotate the RA axis with scope 360 degrees. So if the maximum does not
occur in the allowable range you will have to do some more educated
guesswork, drawing an ellipse and experimenting.

Derek


Fw: Daytime procedure for correcting non-orthogonality

Michael Roth
 

--------- Forwarded message ----------
From: Michael A Roth <maroth@...>
To: ap-gto-owner@...
Date: Mon, 3 Jul 2000 12:09:53 -0400
Subject: Daytime procedure for correcting non-orthogonality
Message-ID: <20000703.120954.-216879.1.maroth@...>

Fellow users:
So, there you are with just about the finest telescope and mount that
money can buy and you can afford. Problem is, no matter how many times
you attempt the published procedures for N Polar calibrate or 2-Star
calibrate, YOU CAN'T GET THIS THING TO GOTO WITH AN ACCEPTABLE DEGREE OF
ACCURACY. The hours go by, discouragement mounts, you iterate and
re-iterate until the disgust and disappointment overwhelm you so bad that
you just go back to star-hopping so the entire night is not wasted.

Guys, I've been there! Christine can't help me, Marj ignores my E-mails,
and Roland. . . . well he's in some kind of rarefied orbit that I
just can't reach. So I took a LOT of time to figure it out on my own.
The telescope and mount are truely fine products but their IS a weak link
in the chain that leads to optical axis orthogonality. The optical axis
must be properly tilted so its axis converges with the extension of the
right ascension axis at a point that is essentially at infinite distance.
It does NOT have to be a star, it can be a distant terrestrial object
like the top of a radio tower, the peak of a ridge, the corner of a
building. Almost anything will do provided it does not move and it is
DISTANT and it is DAYLIGHT. In this respect do yourself a favor, do it
in daylight! You can see, you're not tired or in a hurry, it can even be
cloudy. It will take some time to accomplish but not because it is a
difficult procedure but because their is some learning that must be
acquired to gradually converge the extension of the RA axis with the
telescope's optical axis using the four adjustments you have at your
disposal - altitude azimuth declination and SHIMS.

Before I begin defining the procedure in steps, the objective is to be
able to point the telescope at the same object that is centered in the RA
borehole, swing the telescope at least 180 degrees around the RA axis
(flip then flop) and the object will remain centered in the cross hairs.
With this done, you will be able to set up when darkness falls, follow
the AstroPhysics procedures for N Polar calibrate or 2-Star calibrate to
the letter and the longed-for accuracy you desire will be there.

For shim stock use the thin aluminum that beer or soda cans are made of.
The material is perfect stuff to work with: thin, easy to cut, and you
can even use a paper punch to make the screw holes! Fabricate 6 of them
with dimensions that match the rectangular base of the ring that attaches
to the flat plate. Discard any ideas of using a pliable material like
sheet cork or sheet rubber for shim stock because it will eventually go
out of adjustment. A stack of thin aluminum will not.

Step 1 - Set up on a hard surface, the tripod must not subside in the
least bit like it may on grass. The mount must not be powered. It is
not necessary that the mount be level.

Step 2 - From a distance of at least six feet and with your back
resting against the back of a steady chair, sight up the borehole of the
RA axis and center the terrestrial object you have selected using your
altitude and azimuth adjusters. Patience and learning will be involved
here but take your time and bear in mind that exactly centering this
object is neither possible nor absolutely necessary. Perfection comes
later in another way.

Step 3 - Ensure that your scope is straight up (counterweights down),
RA clutch lever is lightly tight (never tight). Using a crosshair
eyepiece with no diagonal installed swing the telescope in declination
until your target comes into the field of view. We will assume that it
comes into the field of view but is not near the intersection of the
crosshairs.

Step 4 - This is it, the crux, the key, the self-teaching step. This
is where you progressively converge the telescopic axis with the RA axis
using the altitude and azimuth adusters, light taps to the telescope in
declination, and through the addition(or subtraction) of the aluminum
shims. There will be some patience required here because each correction
applied will affect the movement of the crosshairs in a desireable way
and in an undesireable way. Conceptually try to visualize in three
dimensions the formation of a conic section as you check your corrections
by sweeping with the DEC axis now locked and the RA axis unlocked. Watch
how the crosshairs "migrate" around the target. When you reach a point
where the adjustments in ALT/AZ and DEC yield no further positive
results, its time to add or remove a shim. I began with 6 and I ended up
with 2. At this point, I was able to sweep the target about the RA axis
more than 180 degrees(flip/flop) and it remained exactly centered in the
crosshairs. It was a sublime moment.

So ends the procedure.

There are some other points that warrant mentioning. Jack Nicklaus wrote
that a good swing is useless unless it is a CONSISTENTLY good swing. The
felt lining the telescope rings is a crushable material which means if
you tighten one ring more than another you have sacrificed the very thing
you are trying to achieve - orthogonality. Each ring must grip the tel
tube in a consistently repeatable way. To accomplish this, install a
flat steel washer between the butt tabs of the rings and tighten the
knobs. You'll feel what I mean but make sure that the washer is not too
thick or the telly will slide in the rings.

The optical axis of your telescope must be collimated or this procedure
is nothing more than a dog chasing its own damn tail. If you have a
refractor, defocus a moderately bright star. If the light ball is
circular, I think you're OK. Rotating the telescope in the rings and
watching to see if the object moves off the crosshairs is NOT an accurate
assessment of a telescope's collimation it'll only scare the hell out of
you.

In closing, I must in all frankness admit that before you dispel your
orthogonality problem you may, at times feel like a dog chasing its own
tail(this image I owe to Chuck Hancock), but with patience and DAYLIGHT,
you'll catch it as I did!


If you want to talk about this further, feel free to call me anytime. .
. day or night.

Sincerely,
Mike Roth
(607)257-1605


Re: 400 GTO First report

Ron Wodaski <ronw@...>
 

I have a page on AP 600 mods at:

http://www.wodaski.com/wodaski/ap600clamp.htm

There is a link on that page that takes you right to the McMaster-Carr
catalog page:

http://www.mcmaster-carr.com/cgi/loadpage.cgi?pagenum=1870&catnum=106

You will need to have the Adobe Acrobat reader installed to view the catalog
pages, but if you don't, there is a link to download the Acrobat Reader on
the McMaster-Carr page.

Ron Wodaski
http://www.newastro.com

-----Original Message-----
From: Mark B. Wilson [mailto:Markw@...]
Sent: Monday, July 03, 2000 3:59 PM
To: ap-gto@...
Subject: RE: [ap-gto] 400 GTO First report


Where do I get those bat wings? Where is McMaster Carr?

-----Original Message-----
From: Stephen E. Russell [mailto:sjruss55@...]
Sent: Monday, July 03, 2000 12:50 PM
To: ap-gto@...
Subject: Re: [ap-gto] 400 GTO First report


Hi Ron,
I've been using those "bat wing" handles from McMaster Carr now for a couple
of weeks and can't get over how much nicer it is to use them over the OEM
set-up.
Along with the Mylar washers and AP stainless steel washer, I'm still using
a wave washer which I think helps to smooth/steady out the adjustments one
step further. When turning the azimuth knobs the star moves in a straight
line now and doesn't shift when a snug down the "bat handle". Definitely
makes getting polar aligned much easier without the hassle of using the
Allen wrenches.
Stephen

-----Original Message-----
From: Ron Wodaski <ronw@...>
To: ap-gto@... <ap-gto@...>
Date: Monday, July 03, 2000 2:08 PM
Subject: RE: [ap-gto] 400 GTO First report

Have you seen my page on the "bat wing" handles for the az lockdowns on the
600? I also am using Mylar washers to reduce friction, so that I can
tighten
the az lockdowns and still move the mount well enough. I may have some of
those around, if you can't find the washers at your local hardware store.

Ron Wodaski
http://www.newastro.com


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Re: 400 GTO First report

Mark B. Wilson <Markw@...>
 

Where do I get those bat wings? Where is McMaster Carr?

-----Original Message-----
From: Stephen E. Russell [mailto:sjruss55@...]
Sent: Monday, July 03, 2000 12:50 PM
To: ap-gto@...
Subject: Re: [ap-gto] 400 GTO First report


Hi Ron,
I've been using those "bat wing" handles from McMaster Carr now for a couple
of weeks and can't get over how much nicer it is to use them over the OEM
set-up.
Along with the Mylar washers and AP stainless steel washer, I'm still using
a wave washer which I think helps to smooth/steady out the adjustments one
step further. When turning the azimuth knobs the star moves in a straight
line now and doesn't shift when a snug down the "bat handle". Definitely
makes getting polar aligned much easier without the hassle of using the
Allen wrenches.
Stephen

-----Original Message-----
From: Ron Wodaski <ronw@...>
To: ap-gto@... <ap-gto@...>
Date: Monday, July 03, 2000 2:08 PM
Subject: RE: [ap-gto] 400 GTO First report

Have you seen my page on the "bat wing" handles for the az lockdowns on the
600? I also am using Mylar washers to reduce friction, so that I can
tighten
the az lockdowns and still move the mount well enough. I may have some of
those around, if you can't find the washers at your local hardware store.

Ron Wodaski
http://www.newastro.com


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Host your next egroup meeting live on Firetalk.
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Re: 400 GTO First report

Stephen E. Russell <sjruss55@...>
 

Hi Jeff,
Yes, thanks for the suggestion. Its the only way to fly......I mean slew!!!
Stephen

-----Original Message-----
From: Jeffrey D. Gortatowsky <myrocketcatos@...>
To: ap-gto@... <ap-gto@...>
Date: Monday, July 03, 2000 2:37 PM
Subject: Re: [ap-gto] 400 GTO First report


Ron I had those 'bat handles' on order and delivered before the mount
arrived! I just thought I'd try it 'stock' first in case there was a
problem
and it had to be returned. Remember who 'suggested' them? ;^D

Thanks for the tip about pushing the Dec to take up the gear backlash. But
I
am not planning to start imaging for awhile (he says<g>). Too many things
to
see with my eyes first. Besides I am waiting for the FSQ156 and my AP900GTO
first.

Clear skies,
Jeff


Re: 400 GTO First report

Stephen E. Russell <sjruss55@...>
 

Hi Ron,
I've been using those "bat wing" handles from McMaster Carr now for a couple
of weeks and can't get over how much nicer it is to use them over the OEM
set-up.
Along with the Mylar washers and AP stainless steel washer, I'm still using
a wave washer which I think helps to smooth/steady out the adjustments one
step further. When turning the azimuth knobs the star moves in a straight
line now and doesn't shift when a snug down the "bat handle". Definitely
makes getting polar aligned much easier without the hassle of using the
Allen wrenches.
Stephen

-----Original Message-----
From: Ron Wodaski <ronw@...>
To: ap-gto@... <ap-gto@...>
Date: Monday, July 03, 2000 2:08 PM
Subject: RE: [ap-gto] 400 GTO First report

Have you seen my page on the "bat wing" handles for the az lockdowns on the
600? I also am using Mylar washers to reduce friction, so that I can
tighten
the az lockdowns and still move the mount well enough. I may have some of
those around, if you can't find the washers at your local hardware store.

Ron Wodaski
http://www.newastro.com


Re: 400 GTO First report

Brian <brian@...>
 

I have gotten much better results when leveling the 400goto. When leveling
and using an ap polar scope, the mount guides much easier and more
accurately.
Brian

-----Original Message-----
From: Ron Wodaski [mailto:ronw@...]
Sent: Monday, July 03, 2000 2:09 PM
To: ap-gto@...
Subject: RE: [ap-gto] 400 GTO First report


I have never really tried to level the AP mount prior to
polar aligning.
I'll have to see if that makes a difference. I took literally
the advice
that leveling wasn't "necessary," but perhaps it is desirable. <g>

Ron Wodaski
http://www.newastro.com



-----Original Message-----
From: Ray Gralak [mailto:ray@...]
Sent: Monday, July 03, 2000 11:48 AM
To: ap-gto@...
Subject: RE: [ap-gto] 400 GTO First report


The 1200 is also just plain better for polar aligning than
the 600 GTO
mount. There isn't much flexure in the 1200, while the 600
has enough to
cause some trouble during polar alignment. I suppose the
flexure will
depend

Perhaps, but I learned this technique with my old Vixen GP +
SS2000+ Tak
FS-102.
This mount is much more flexible than a 600<g>. It worked
great then as long
as the mount was level which was easy to do with the tripod.

-Ray Gralak

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Re: 400 GTO First report

Jeffrey D. Gortatowsky
 

Ron I had those 'bat handles' on order and delivered before the mount
arrived! I just thought I'd try it 'stock' first in case there was a problem
and it had to be returned. Remember who 'suggested' them? ;^D

Thanks for the tip about pushing the Dec to take up the gear backlash. But I
am not planning to start imaging for awhile (he says<g>). Too many things to
see with my eyes first. Besides I am waiting for the FSQ156 and my AP900GTO
first.

Clear skies,
Jeff

----- Original Message -----
From: "Ron Wodaski" <ronw@...>
To: <ap-gto@...>
Sent: Monday, July 03, 2000 12:12 PM
Subject: RE: [ap-gto] 400 GTO First report


You can actually get some advantages from not being perfectly polar
aligned.
You can cover backlash in Dec, for example, by deliberately mis-aligning
so
that the mount is always pushing the Dec in one direction, so that you
never
encounter the backlash.

Have you seen my page on the "bat wing" handles for the az lockdowns on
the
600? I also am using Mylar washers to reduce friction, so that I can
tighten
the az lockdowns and still move the mount well enough. I may have some of
those around, if you can't find the washers at your local hardware store.

Ron Wodaski
http://www.newastro.com



-----Original Message-----
From: Jeffrey D. Gortatowsky [mailto:myrocketcatos@...]
Sent: Monday, July 03, 2000 11:56 AM
To: ap-gto@...
Subject: Re: [ap-gto] 400 GTO First report



----- Original Message -----
From: "Ron Wodaski" <ronw@...>
orthogonality, though my refractor was best for polar aligning; the
9.25"
SCT was hopeless. <g>
Why? Because of the mirror shift I guess? I found that when you tighten
the
two azimuth lock screws the mount does shift. Of course there is 40 pounds
or more of stress. I found the movement about 3 to 4 arc-minutes and I
could
'lead' them (though a PITA). For imaging you want an alignment as close as
possible if not perfect. But realistically how close is close enough?



Clear skies,
Jeff

BTW: Can you autograph my copy of TNA? <vbg>



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Re: 400 GTO First report

Ron Wodaski <ronw@...>
 

You can actually get some advantages from not being perfectly polar aligned.
You can cover backlash in Dec, for example, by deliberately mis-aligning so
that the mount is always pushing the Dec in one direction, so that you never
encounter the backlash.

Have you seen my page on the "bat wing" handles for the az lockdowns on the
600? I also am using Mylar washers to reduce friction, so that I can tighten
the az lockdowns and still move the mount well enough. I may have some of
those around, if you can't find the washers at your local hardware store.

Ron Wodaski
http://www.newastro.com

-----Original Message-----
From: Jeffrey D. Gortatowsky [mailto:myrocketcatos@...]
Sent: Monday, July 03, 2000 11:56 AM
To: ap-gto@...
Subject: Re: [ap-gto] 400 GTO First report



----- Original Message -----
From: "Ron Wodaski" <ronw@...>
orthogonality, though my refractor was best for polar aligning; the 9.25"
SCT was hopeless. <g>
Why? Because of the mirror shift I guess? I found that when you tighten the
two azimuth lock screws the mount does shift. Of course there is 40 pounds
or more of stress. I found the movement about 3 to 4 arc-minutes and I could
'lead' them (though a PITA). For imaging you want an alignment as close as
possible if not perfect. But realistically how close is close enough?



Clear skies,
Jeff

BTW: Can you autograph my copy of TNA? <vbg>



------------------------------------------------------------------------
Was the salesman clueless? Productopia has the answers.
http://click.egroups.com/1/4633/7/_/3615/_/962650430/
------------------------------------------------------------------------


Re: 400 GTO First report

Ron Wodaski <ronw@...>
 

I have never really tried to level the AP mount prior to polar aligning.
I'll have to see if that makes a difference. I took literally the advice
that leveling wasn't "necessary," but perhaps it is desirable. <g>

Ron Wodaski
http://www.newastro.com

-----Original Message-----
From: Ray Gralak [mailto:ray@...]
Sent: Monday, July 03, 2000 11:48 AM
To: ap-gto@...
Subject: RE: [ap-gto] 400 GTO First report


The 1200 is also just plain better for polar aligning than the 600 GTO
mount. There isn't much flexure in the 1200, while the 600 has enough to
cause some trouble during polar alignment. I suppose the flexure will
depend

Perhaps, but I learned this technique with my old Vixen GP + SS2000+ Tak
FS-102.
This mount is much more flexible than a 600<g>. It worked great then as long
as the mount was level which was easy to do with the tripod.

-Ray Gralak

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Re: 400 GTO First report

Jeffrey D. Gortatowsky
 

----- Original Message -----
From: "Ron Wodaski" <ronw@...>
orthogonality, though my refractor was best for polar aligning; the 9.25"
SCT was hopeless. <g>
Why? Because of the mirror shift I guess? I found that when you tighten the
two azimuth lock screws the mount does shift. Of course there is 40 pounds
or more of stress. I found the movement about 3 to 4 arc-minutes and I could
'lead' them (though a PITA). For imaging you want an alignment as close as
possible if not perfect. But realistically how close is close enough?



Clear skies,
Jeff

BTW: Can you autograph my copy of TNA? <vbg>


Re: 400 GTO First report

Ray Gralak <ray@...>
 

The 1200 is also just plain better for polar aligning than the 600 GTO
mount. There isn't much flexure in the 1200, while the 600 has enough to
cause some trouble during polar alignment. I suppose the flexure will depend
Perhaps, but I learned this technique with my old Vixen GP + SS2000+ Tak FS-102.
This mount is much more flexible than a 600<g>. It worked great then as long
as the mount was level which was easy to do with the tripod.

-Ray Gralak


Re: 400 GTO First report

Ron Wodaski <ronw@...>
 

The 1200 is also just plain better for polar aligning than the 600 GTO
mount. There isn't much flexure in the 1200, while the 600 has enough to
cause some trouble during polar alignment. I suppose the flexure will depend
on the weight you've got on the mount. And I can't say that I've tested
orthogonality, though my refractor was best for polar aligning; the 9.25"
SCT was hopeless. <g>

Ron Wodaski
http://www.newastro.com

-----Original Message-----
From: Ray Gralak [mailto:ray@...]
Sent: Monday, July 03, 2000 11:00 AM
To: ap-gto@...
Subject: RE: [ap-gto] 400 GTO First report


Hi Ron,

Usually the 1/2 way won't work well if the mount is not very level.
In that case, you will get one axis affecting the other. Otherwise it
has always worked quite well for me (30+ times with my 1200). Of course
the OTA has to be close to orthogonal too.

-Ray

-----Original Message-----
From: Ron Wodaski [mailto:ronw@...]
Sent: Monday, July 03, 2000 10:49 AM
To: ap-gto@...
Subject: RE: [ap-gto] 400 GTO First report


It's not always the case that half-way will work for you, and I wondered
why. I have a theory, of course <g>.

The basis of my theory is this (untested) assumption, but I think it's
true:
because the two coordinate systems (alt-az and equatorial) are oriented so
differently, making a change to a single axis (alt or az) can affect
position in the other coordinate system along two axes (RA and Dec).

For example, if one axis (alt or az) is very close to correct, and the
other
is not, you should avoid making changes to the one that is close to
correct,
and concentrate on getting the other one close to correct, too. I haven't
had to do this kind of polar alignment for several months, so my
experience
isn't fresh. I'm currently using a polar scope on an NJP 160, although I
have a 400 GTO coming and will have to re-learn these skills.

But as I recall, if one axis was close, and I made adjustments to two axes
(alt and az), the axis that was close to correct would oscillate
(overshoot). I would then move that axis to the mid position (between the
extremes of the oscillation), and then leave it alone and concentrate on
bringing the other axis close to correct position. Once both were of
nearly
equal magnitude, I could then quickly get a good alignment by adjusting
both
together.

I have even had situations where I have had to go _double_ the distance,
rather than half the distance, to get aligned in a reasonable number of
iterations. If memory serves, that tended to be the case when I was
aligning
to stars on different sides of the meridian, but it has been a while and
I'm
not entirely sure.

Ron Wodaski
http://www.newastro.com



-----Original Message-----
From: Ray Gralak [mailto:ray@...]
Sent: Monday, July 03, 2000 10:27 AM
To: ap-gto@...
Subject: RE: [ap-gto] 400 GTO First report


I figured six times meant I might have the dreaded 'orthogonalilty'
problem.
Now how in @^#$ am I suppose to shim this scope when it's mounted. Man
that
looks like a non-newmoon night task. I am not gonna try that in the
complete
dark!
Hi Jeff,

To cut down on the iterations when polar aligning your scope
for each iteration you should only adjust the altitude and azimuth
adjustments to move Polaris half-way to the center of your finder (or
eyepiece when you get sufficiently close). If you put Polaris in
the center each time you will overshoot the correction and it will
take more iterations.

-Ray Gralak



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Re: 400 GTO First report

Jeffrey D. Gortatowsky
 

Thanks for the tip Ray. You know the ortho check talks about moving halfway
as does one of the polar alignment methods IIRC. My manuals are in the mount
case so I can't refer to them right now. But I don't think method number one
(N. Polar Align) calls for half movements. Thanks. I did level the mount
(habit) so I'll give it a try.

Wonder if the manuals are in Word or sompin'. I think I have a PDF writer
printer driver....

Clear skies,
Jeff

----- Original Message -----
From: "Ray Gralak" <ray@...>


Hi Ron,

Usually the 1/2 way won't work well if the mount is not very level.
In that case, you will get one axis affecting the other. Otherwise it
has always worked quite well for me (30+ times with my 1200). Of course
the OTA has to be close to orthogonal too.

-Ray


Re: Manuals online?

Jeffrey D. Gortatowsky
 

They are not online so far as I can ascertain. When discussing things here
it would be handy to refer to a PDF manual. Alas I know not of one. And like
a good boy scout, I keep my mount manuals with the mount which is not anyway
near my desktop!<g>

Load carrying wise, is the G11 about the same as a 600EGTO or 900GTO?

Clear skies,
Jeff

----- Original Message -----
From: <sreilly@...>
As I await patiently for a call on the AP900GTO's I thought that being
able to read over a manual would be a great help. Anyone have a 900
manual online anywhere? Any suggestions? Thanks in advance. Currently I
am using a Losmandy G-11 german mount.


Re: 400 GTO First report

Ray Gralak <ray@...>
 

Hi Ron,

Usually the 1/2 way won't work well if the mount is not very level.
In that case, you will get one axis affecting the other. Otherwise it
has always worked quite well for me (30+ times with my 1200). Of course
the OTA has to be close to orthogonal too.

-Ray

-----Original Message-----
From: Ron Wodaski [mailto:ronw@...]
Sent: Monday, July 03, 2000 10:49 AM
To: ap-gto@...
Subject: RE: [ap-gto] 400 GTO First report


It's not always the case that half-way will work for you, and I wondered
why. I have a theory, of course <g>.

The basis of my theory is this (untested) assumption, but I think it's true:
because the two coordinate systems (alt-az and equatorial) are oriented so
differently, making a change to a single axis (alt or az) can affect
position in the other coordinate system along two axes (RA and Dec).

For example, if one axis (alt or az) is very close to correct, and the other
is not, you should avoid making changes to the one that is close to correct,
and concentrate on getting the other one close to correct, too. I haven't
had to do this kind of polar alignment for several months, so my experience
isn't fresh. I'm currently using a polar scope on an NJP 160, although I
have a 400 GTO coming and will have to re-learn these skills.

But as I recall, if one axis was close, and I made adjustments to two axes
(alt and az), the axis that was close to correct would oscillate
(overshoot). I would then move that axis to the mid position (between the
extremes of the oscillation), and then leave it alone and concentrate on
bringing the other axis close to correct position. Once both were of nearly
equal magnitude, I could then quickly get a good alignment by adjusting both
together.

I have even had situations where I have had to go _double_ the distance,
rather than half the distance, to get aligned in a reasonable number of
iterations. If memory serves, that tended to be the case when I was aligning
to stars on different sides of the meridian, but it has been a while and I'm
not entirely sure.

Ron Wodaski
http://www.newastro.com



-----Original Message-----
From: Ray Gralak [mailto:ray@...]
Sent: Monday, July 03, 2000 10:27 AM
To: ap-gto@...
Subject: RE: [ap-gto] 400 GTO First report


I figured six times meant I might have the dreaded 'orthogonalilty'
problem.
Now how in @^#$ am I suppose to shim this scope when it's mounted. Man
that
looks like a non-newmoon night task. I am not gonna try that in the
complete
dark!
Hi Jeff,

To cut down on the iterations when polar aligning your scope
for each iteration you should only adjust the altitude and azimuth
adjustments to move Polaris half-way to the center of your finder (or
eyepiece when you get sufficiently close). If you put Polaris in
the center each time you will overshoot the correction and it will
take more iterations.

-Ray Gralak



------------------------------------------------------------------------
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http://click.egroups.com/1/6137/7/_/3615/_/962645188/
------------------------------------------------------------------------




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------------------------------------------------------------------------



Re: 400 GTO First report

Ron Wodaski <ronw@...>
 

It's not always the case that half-way will work for you, and I wondered
why. I have a theory, of course <g>.

The basis of my theory is this (untested) assumption, but I think it's true:
because the two coordinate systems (alt-az and equatorial) are oriented so
differently, making a change to a single axis (alt or az) can affect
position in the other coordinate system along two axes (RA and Dec).

For example, if one axis (alt or az) is very close to correct, and the other
is not, you should avoid making changes to the one that is close to correct,
and concentrate on getting the other one close to correct, too. I haven't
had to do this kind of polar alignment for several months, so my experience
isn't fresh. I'm currently using a polar scope on an NJP 160, although I
have a 400 GTO coming and will have to re-learn these skills.

But as I recall, if one axis was close, and I made adjustments to two axes
(alt and az), the axis that was close to correct would oscillate
(overshoot). I would then move that axis to the mid position (between the
extremes of the oscillation), and then leave it alone and concentrate on
bringing the other axis close to correct position. Once both were of nearly
equal magnitude, I could then quickly get a good alignment by adjusting both
together.

I have even had situations where I have had to go _double_ the distance,
rather than half the distance, to get aligned in a reasonable number of
iterations. If memory serves, that tended to be the case when I was aligning
to stars on different sides of the meridian, but it has been a while and I'm
not entirely sure.

Ron Wodaski
http://www.newastro.com

-----Original Message-----
From: Ray Gralak [mailto:ray@...]
Sent: Monday, July 03, 2000 10:27 AM
To: ap-gto@...
Subject: RE: [ap-gto] 400 GTO First report


I figured six times meant I might have the dreaded 'orthogonalilty'
problem.
Now how in @^#$ am I suppose to shim this scope when it's mounted. Man
that
looks like a non-newmoon night task. I am not gonna try that in the
complete
dark!
Hi Jeff,

To cut down on the iterations when polar aligning your scope
for each iteration you should only adjust the altitude and azimuth
adjustments to move Polaris half-way to the center of your finder (or
eyepiece when you get sufficiently close). If you put Polaris in
the center each time you will overshoot the correction and it will
take more iterations.

-Ray Gralak



------------------------------------------------------------------------
Life's too short to send boring email. Let SuperSig come to the rescue.
http://click.egroups.com/1/6137/7/_/3615/_/962645188/
------------------------------------------------------------------------


Re: 400 GTO First report

Ray Gralak <ray@...>
 

I figured six times meant I might have the dreaded 'orthogonalilty' problem.
Now how in @^#$ am I suppose to shim this scope when it's mounted. Man that
looks like a non-newmoon night task. I am not gonna try that in the complete
dark!
Hi Jeff,

To cut down on the iterations when polar aligning your scope
for each iteration you should only adjust the altitude and azimuth
adjustments to move Polaris half-way to the center of your finder (or
eyepiece when you get sufficiently close). If you put Polaris in
the center each time you will overshoot the correction and it will
take more iterations.

-Ray Gralak