As the owner of a Nexstar 8, accurate polar alignment for phtotgraphy can sometimes be a chore. The technique I use is relatively simple, and I can get an accurate alignment about half the time.
I've found a couple new resources (new to me) regarding alignment techniques which refine what I already do, but I'm hoping to get some input from all of you regarding what works for you and what you have found to be a reliable method.
When I go through an alignment, here's what I do.
1) Mount the scope on a wedge and point it at Polaris. I physically adjust the wedge up and down so the eyepiece shows Polaris just outside the eyepiece (I use a 40mm plossl) FOV and is positioned to show the angle between Polaris and Kochab (this is where true north is). About .85 degrees off Polaris.
2) Make sure the scope is level. I use a small round bubble-level for this. But this isn't done until after I have the OTA pointing at Polaris.
3) Turn on the scope, select Auto-Align and point the OTA at the ground. Since it's on a wedge, North and Level really means pointing the OTA so it's perpendicular to the fork arm, which means it's really pointing at the ground.
4) Enter date, time, Lat and Long
5) Go to first star, center it using the up and right arrows on my handset, then repeat the process for the second star.
*Note: I try to use stars in opposite sides of the sky, but sometimes it's not possible. I found some information that may help with this and will post it here after this.
That's it.
Below is a couple of links I found which provide further details for this process. I'd like to hear from anyone who uses methods that may provide greater accuracy, or tend to be more consistent.
Thanks for sharing and Clear Skies to you all.
David
http://www.allaboutastro.com/Articlepages/iterativemethod.html
http://home.earthlink.net/~mjbarrell/setup.htm
I've found a couple new resources (new to me) regarding alignment techniques which refine what I already do, but I'm hoping to get some input from all of you regarding what works for you and what you have found to be a reliable method.
When I go through an alignment, here's what I do.
1) Mount the scope on a wedge and point it at Polaris. I physically adjust the wedge up and down so the eyepiece shows Polaris just outside the eyepiece (I use a 40mm plossl) FOV and is positioned to show the angle between Polaris and Kochab (this is where true north is). About .85 degrees off Polaris.
2) Make sure the scope is level. I use a small round bubble-level for this. But this isn't done until after I have the OTA pointing at Polaris.
3) Turn on the scope, select Auto-Align and point the OTA at the ground. Since it's on a wedge, North and Level really means pointing the OTA so it's perpendicular to the fork arm, which means it's really pointing at the ground.
4) Enter date, time, Lat and Long
5) Go to first star, center it using the up and right arrows on my handset, then repeat the process for the second star.
*Note: I try to use stars in opposite sides of the sky, but sometimes it's not possible. I found some information that may help with this and will post it here after this.
That's it.
Below is a couple of links I found which provide further details for this process. I'd like to hear from anyone who uses methods that may provide greater accuracy, or tend to be more consistent.
Thanks for sharing and Clear Skies to you all.
David
http://www.allaboutastro.com/Articlepages/iterativemethod.html
http://home.earthlink.net/~mjbarrell/setup.htm
