RE: [APML]OT-Drift Alignment

["Serge Theberge" <serge.theberge@wti.on.ca>]

Hi Dwight,

Thanks for the reference to Scot Tuckers web site and for qualifying the
extent to which you drift align your mount.

I noticed that Scot Tuckers cites 5 minutes with no drift as being good
enough, while you use 10-15 minutes @ 300X with no drift.  I suspect that
depending on what kind of photo exposure and magnification you use, that 5
minutes is sometimes "good enough" and some other (much more infrequent)
times 15 minutes might not be "good enough".  This is why I am looking for
some kind of formula or rule of thumb that would define maximum polar
alignment error tolerance vs. exposure time, magnification, etc.

Serge Theberge
Toronto Centre
RASC
-----Original Message-----
From: astro-photo-bounces@seds.org [mailto:astro-photo-bounces@seds.org] On
Behalf Of DBogan3220@aol.com
Sent: Tuesday, November 25, 2003 8:23 PM
To: astro-photo@seds.org
Subject: Re: [APML]OT-Drift Alignment


http://www.darkskyimages.com/gpolar.html

Go to the above WEB site Scot Tuckers explanation for drift alignment is
probably one of the best explanations on how to go about this.  BTW I drift
align at 300x and make adjustments until I have no drift for 10 to 15
minutes. It is not that difficult to do. And should be done every time. I
even do it for piggy back with camera lenses. I use an AP 900 goto with my
AP 6 inch F7 and I perform the same procedure with my 10 inch AP Mak. I
should also note that my pointing accuracy with the 900 goto is dead nuts on
when I drift align, not too shabby for a 5 year old mount!

       Clear Skies
       Dwight L Bogan




In a message dated 11/25/2003 6:03:50 PM US Mountain Standard Time,
serge.theberge@wti.on.ca writes:
I have been told that for astrophotography, not only you must have a good,
sturdy mount, but you must have good polar alignment.  I have seen various
rules of thumb about what is "good enough" polar alignment such as no
visible drift @ 200X for 5 minutes, others state 15 minutes, etc.  My guess
is that there must be some kind of formula (or rule of thumb) linking
"maximum acceptable polar alignment error" to f-speed, magnification, film
grain size, exposure duration, etc.  Can anyone enlighten me on this?

Thanks

Serge Theberge
Toronto Centre
RASC

> -----Original Message-----
> From: astro-photo-bounces@seds.org 
> [mailto:astro-photo-bounces@seds.org] On Behalf Of Franklin A. Holub
> Sent: Monday, November 24, 2003 4:25 PM
> To: Discussion of Film Astrophotography
> Subject: Re: [APML]OT-Drift Alignment
> 
> 
> I haven't posted in a while but lets see if I can really mess 
> things up... I'm going to make a statement that is going to 
> fly in the face of years of experience and is going to 
> contradict what we have always been told about drift alignment...
> 
> But first, a little background...
> 
> After a couple of years of being happy with "close enough" 
> polar alignment, I installed a perminant pier and I figured 
> it was time to "nail" my polar alignment. <snip>


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