Ok heres the story, i have a meade LX-6, and im looking to do some astrophotography. I know how to roughly polar align just fine, but the past 4 nights ive been working to get it as close to perfect as i can and i cant come close. I tried aligning with Arcturus tonigh and it kept drifting right (in the eyepiece). So someone told me if it moves eat or west that my mount needs to go up or down, so i tried both. BOTH ways the Arcturus STILL drifted the same way, and about the same distance. I cant figure this out and im getting angry. Also i just tried my meade off axis guider for the first time with my olympus om-1 only to find the eyepiece i put it doesntfocus right on any stars, when its focused in the camera its not in the eyepiece. Can ANYONE help me with these problems?
Polar Alignment
Started by Astronomer2b, 06/12/2002 04:56AM
Posted 06/12/2002 04:56AM
Opening Post
Posted 06/12/2002 11:37AM
#1
Go to http://www.astroleague.org/al/astrnote/astnot01.html
There methods worked very well for me. I use a GEM but the principle is the same with the fork mount or whatever.
Walt
There methods worked very well for me. I use a GEM but the principle is the same with the fork mount or whatever.
Walt
Posted 06/12/2002 01:10PM
#2
One thing I was surprised to realize when I first started to polar align using the drift method is that your adjustments are likely to be much larger than you anticipate. If you can see drift fairly quickly, you may be as much as three or four eyepiece fields of view off. So, go ahead and crank the adjusters.
In short, the reason that Arcturus still drifts after you adjust is that you need to adjust al LOT more.
As for the focusing of the eyepiece/camera--what you need to do is focus the camera dead on--and then never touch the focusing knob. Put the eyepiece in its tube and move it in and out until it gets focuses. If you cannot move it in far enough, you may need some kind of adapter to move the camera back further. Or if when you do get the eyepiece to focus, there is not enough of it in the tube to hold firm when you tighten the setscrew, you will need an extension to hold the eyepiece out further (my OAG has a three inch extension). You may want to try a Barlow in it first. This sometimes changes how much travel you need in the drawtube.
If you can get it to focus, scribe or mark (or put a "parfocalizing" ring) on the eyepiece so that you know wehre it should be in the tube each time to match your camera.
Alex
In short, the reason that Arcturus still drifts after you adjust is that you need to adjust al LOT more.
As for the focusing of the eyepiece/camera--what you need to do is focus the camera dead on--and then never touch the focusing knob. Put the eyepiece in its tube and move it in and out until it gets focuses. If you cannot move it in far enough, you may need some kind of adapter to move the camera back further. Or if when you do get the eyepiece to focus, there is not enough of it in the tube to hold firm when you tighten the setscrew, you will need an extension to hold the eyepiece out further (my OAG has a three inch extension). You may want to try a Barlow in it first. This sometimes changes how much travel you need in the drawtube.
If you can get it to focus, scribe or mark (or put a "parfocalizing" ring) on the eyepiece so that you know wehre it should be in the tube each time to match your camera.
Alex
Posted 06/15/2002 06:49PM
#3
For precise polar alignmentyou need to do a drift alignment. Also something that you might think of is what is you mean photographic declination? For me here in SE Arizona, it is about +22, for somewhere further north, it will be higher. Basically what this does if average out your drift for most of the sky. You will not be shoooting pictures at -50 declination and probably not a +80 either so you need to find your "average" which is partially based on your latitude.
So, assuming that you are aligned reasonably well north, point the scope to your mean photographic declination and the meridian. you will need a high power guiding eyepiece with illuminated crosshairs. Align it so that when you move in Dec it moves on on line and RA moved the other line. Also note which way is north and south IN THE EYEPIECE. find a star and set in on the N/S line and watch it drift in declination only and note its direction of drift. If the star moves north, move the scope toward the east, if the star moves south, move to the west. hopefully your mount will allow you to make small adjustments. Adjust untill there is no drift for 10 minutes. Now point the scope over low in the east, keeping it at your mean photographic declination (only move in RA). Again figure out which way is north/south in the eyepiece, center a star on the N/S line and watch drift. If it drift north, adjust polar axis down, if it drift south move polar axis up. Again there should be no drift in 10 minutes. Now go back to the meridian and do it again but shoot for 20 minutes with no drift, then go back to the east.
Also keep in mind that if you need to move the scope a bit to find a bright star that is OK but no more than like 1/2 degree, less if possible. Also when you are drifting keep in mind your starting position and don't get too far from it. You might need to move east and find another star. Also, keep in mind that this procedure can take a bit of time but when done you will have a very accurate polar alignment.
Mike
So, assuming that you are aligned reasonably well north, point the scope to your mean photographic declination and the meridian. you will need a high power guiding eyepiece with illuminated crosshairs. Align it so that when you move in Dec it moves on on line and RA moved the other line. Also note which way is north and south IN THE EYEPIECE. find a star and set in on the N/S line and watch it drift in declination only and note its direction of drift. If the star moves north, move the scope toward the east, if the star moves south, move to the west. hopefully your mount will allow you to make small adjustments. Adjust untill there is no drift for 10 minutes. Now point the scope over low in the east, keeping it at your mean photographic declination (only move in RA). Again figure out which way is north/south in the eyepiece, center a star on the N/S line and watch drift. If it drift north, adjust polar axis down, if it drift south move polar axis up. Again there should be no drift in 10 minutes. Now go back to the meridian and do it again but shoot for 20 minutes with no drift, then go back to the east.
Also keep in mind that if you need to move the scope a bit to find a bright star that is OK but no more than like 1/2 degree, less if possible. Also when you are drifting keep in mind your starting position and don't get too far from it. You might need to move east and find another star. Also, keep in mind that this procedure can take a bit of time but when done you will have a very accurate polar alignment.
Mike
Posted 06/15/2002 06:49PM
#4
For precise polar alignmentyou need to do a drift alignment. Also something that you might think of is what is you mean photographic declination? For me here in SE Arizona, it is about +22, for somewhere further north, it will be higher. Basically what this does if average out your drift for most of the sky. You will not be shoooting pictures at -50 declination and probably not a +80 either so you need to find your "average" which is partially based on your latitude.
So, assuming that you are aligned reasonably well north, point the scope to your mean photographic declination and the meridian. you will need a high power guiding eyepiece with illuminated crosshairs. Align it so that when you move in Dec it moves on on line and RA moved the other line. Also note which way is north and south IN THE EYEPIECE. find a star and set in on the N/S line and watch it drift in declination only and note its direction of drift. If the star moves north, move the scope toward the east, if the star moves south, move to the west. hopefully your mount will allow you to make small adjustments. Adjust untill there is no drift for 10 minutes. Now point the scope over low in the east, keeping it at your mean photographic declination (only move in RA). Again figure out which way is north/south in the eyepiece, center a star on the N/S line and watch drift. If it drift north, adjust polar axis down, if it drift south move polar axis up. Again there should be no drift in 10 minutes. Now go back to the meridian and do it again but shoot for 20 minutes with no drift, then go back to the east.
Also keep in mind that if you need to move the scope a bit to find a bright star that is OK but no more than like 1/2 degree, less if possible. Also when you are drifting keep in mind your starting position and don't get too far from it. You might need to move east and find another star. Also, keep in mind that this procedure can take a bit of time but when done you will have a very accurate polar alignment.
Mike
So, assuming that you are aligned reasonably well north, point the scope to your mean photographic declination and the meridian. you will need a high power guiding eyepiece with illuminated crosshairs. Align it so that when you move in Dec it moves on on line and RA moved the other line. Also note which way is north and south IN THE EYEPIECE. find a star and set in on the N/S line and watch it drift in declination only and note its direction of drift. If the star moves north, move the scope toward the east, if the star moves south, move to the west. hopefully your mount will allow you to make small adjustments. Adjust untill there is no drift for 10 minutes. Now point the scope over low in the east, keeping it at your mean photographic declination (only move in RA). Again figure out which way is north/south in the eyepiece, center a star on the N/S line and watch drift. If it drift north, adjust polar axis down, if it drift south move polar axis up. Again there should be no drift in 10 minutes. Now go back to the meridian and do it again but shoot for 20 minutes with no drift, then go back to the east.
Also keep in mind that if you need to move the scope a bit to find a bright star that is OK but no more than like 1/2 degree, less if possible. Also when you are drifting keep in mind your starting position and don't get too far from it. You might need to move east and find another star. Also, keep in mind that this procedure can take a bit of time but when done you will have a very accurate polar alignment.
Mike
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