I am glad Roland brought up using a finder. The whole point of the
meridian flip method is to polar align the mount. Making the optics
perfectly orthogonal is secondary and unnecessary. It might make
things a little simpler to understand if you do both as Roland
describes, N-S for the inclination error and E-W for the orthogonal
error when using the meridian delay flipping. Using the finder seems
to really speed things up and if one wants to get super accurate,
going to a CCD technique in the main instrument would quickly
fine-tune the polar alignment. I like it!


--- In ap-gto@..., "Joseph Zeglinski" <J.Zeglinski@...> wrote:

Hi Rolando,

I too was a bit confused, but let that slip. Now I am really

confused.

I understand your method and the explanation is clear, but I don't

get the

"initial conditions".

Was the main OTA (with finder on top), already perfectly

orthogonal to

the mount, or is the finder physically attached to the AP-3200

mount, and

therefore requires its own alignment? Even with the latter,

adjusting the

mount Alt-Az knobs for the finder, ruins the OTA derived mount

alignment.

Saying:
*
******
The advantage of using the 8x50 finder was that i could quickly

adjust it

via
the thumbscrews to be perfectly orthogonal to the mount (unlike the

Big Mak

which was off about 15 arc minutes).
******

... implies that this was an "initial installation", and the finder

and OTA

were not yet aligned to each other.
I would have started by aligning the finder to the OTA using an
"illuminated cross hair eyepiece", until these two were parallel,

and then

go through your procedure to make the OTA/finder orthogonal with

the mount,

and then also polar aligned.

The way I read this, you are making the (OTA attached) finder

orthogonal

to the mount, and once completed, you then need to repeat for the

main OTA -

which now misaligns the finder.

The only way this explanation would seem right to me - is if you

had

said that the OTA was already previously orthogonal to the mount,

and the

procedure was merely to do the same for the finder.
But that is a harder way to do that than using a cross hair eyepiece

in the

first place. The only saving is the purchase of that special

eyepiece, which

I assume most of us already own.

Thanks for a further clarification.
Joe

----- Original Message -----
From: <chris1011@...>
To: <ap-gto@...>
Sent: Saturday, September 20, 2008 11:54 AM
Subject: Re: [ap-gto] Re: An easier Pasillx N & S Polar Alignment method

The mount's altitude axis

is properly set and the finderscope's adjuster screws are also

properly

set, so
you are 1/2 polar aligned and the finder is perfectly orthogonal.

Rolando