- Configure your scope as usual. To approximately align using Polaris, use one of the several ways available. This may be as simple as centering Polaris in your sighter scope. The closer you get, the less time you’ll waste floating. (Tip: Level your tripod or permanent pier to make your life simpler.)Equatorial Mount
2. Fit your Equatorial Mount scope with a diagonal and lit guiding eyepiece. A minimum of 200 watts is required for appropriate sensitivity when drifting. When using the slow motion settings, rotate the eyepiece such that a star travels parallel to the crosshairs in Dec and RA. Align it such that Dec is going up and down (North and South) and RA is going right and left (East & West).
3. Locate a star around the meridian and +20 degrees declination and line it with the center of the guiding eyepiece. Allow your Equatorial Mount scope to track (you may just guide in RA if you like) and keep an eye out for Dec drift (up or down). Unless your alignment is really precise, you will notice a drift in 5 to 30 seconds (you can work with out-of-focus images).
4. If the star wanders upward, adjust the azimuth knob until the star moves directly into the field. If the star wanders downward, adjust the azimuth knob so that the star moves to the left in the field (These adjustments are reversed for a Newtonian). After adjusting the star,Equatorial Mount use the slow-motion controls to re-center it. Repeat for at least 5 minutes, or until there is no drift. Please keep in mind that if you see drift in less than 5 seconds at 200X, you are probably 10 or more eyepiece fields off in azimuth. Turn the knob all the way up. This may need to be done three or four times to observe the drift slowing. If you don’t see any drift after around 30 seconds, you could just be 1 or 2 eyepiece fields off. Make the necessary azimuth adjustments. If the star wanders in the other way after correction, you went too far.
5. Find a star that is on the equator and within 15 degrees of the Eastern or Western horizon. Repeat (2) and use the guidelines from (3) and (4). If the star travels up on the eastern horizon, change the elevation to lower it down. If the star falls, modify the elevation to bring it back up. If the star moves up on the Western horizon, increase the elevation to shift the star higher. Adjust the elevation to move the star down if it travels down. Repeat for at least 5 minutes, or until there is no drift.
6. If you performed a significant elevation adjustment (several degrees or more), go back and verify the azimuth; otherwise, you are finished. With a little practice, you should be able to finish the technique before the end of twilight. Experiment with it in your backyard until you’re confident. For declinations between +70 and -70 degrees, I found this approach to be precise enough for astrophotographs lasting up to 3 hours for small fields (less than 1 degree) and up to 2 hours for bigger fields (up to 5 degrees). For longer exposures and closer to the poles, a photographic polar alignment approach applicable exclusively to permanent installations may be necessary.
7. It should be noted that the star cannot wander at all for 5 minutes in order to reach the exposure periods specified above. If the drift is measured by bisecting a star with a line in an illuminated eyepiece, the star must remain bisected for the whole 5 minutes. Field rotation will begin to sneak into lengthy exposures if the star has migrated as little as half its diameter, according to experience.
Equatorial Mount: Conclusion We hope you have enjoyed this comprehensive article on Equatorial Mount
- Configure your scope as usual. To approximately align using Polaris, use one of the several ways available. This may be as simple as centering Polaris in your sighter scope. The closer you get, the less time you’ll waste floating. (Tip: Level your tripod or permanent pier to make your life simpler.)Equatorial Mount
2. Fit your Equatorial Mount scope with a diagonal and lit guiding eyepiece. A minimum of 200 watts is required for appropriate sensitivity when drifting. When using the slow motion settings, rotate the eyepiece such that a star travels parallel to the crosshairs in Dec and RA. Align it such that Dec is going up and down (North and South) and RA is going right and left (East & West).
3. Locate a star around the meridian and +20 degrees declination and line it with the center of the guiding eyepiece. Allow your Equatorial Mount scope to track (you may just guide in RA if you like) and keep an eye out for Dec drift (up or down). Unless your alignment is really precise, you will notice a drift in 5 to 30 seconds (you can work with out-of-focus images).
4. If the star wanders upward, adjust the azimuth knob until the star moves directly into the field. If the star wanders downward, adjust the azimuth knob so that the star moves to the left in the field (These adjustments are reversed for a Newtonian). After adjusting the star,Equatorial Mount use the slow-motion controls to re-center it. Repeat for at least 5 minutes, or until there is no drift. Please keep in mind that if you see drift in less than 5 seconds at 200X, you are probably 10 or more eyepiece fields off in azimuth. Turn the knob all the way up. This may need to be done three or four times to observe the drift slowing. If you don’t see any drift after around 30 seconds, you could just be 1 or 2 eyepiece fields off. Make the necessary azimuth adjustments. If the star wanders in the other way after correction, you went too far.
5. Find a star that is on the equator and within 15 degrees of the Eastern or Western horizon. Repeat (2) and use the guidelines from (3) and (4). If the star travels up on the eastern horizon, change the elevation to lower it down. If the star falls, modify the elevation to bring it back up. If the star moves up on the Western horizon, increase the elevation to shift the star higher. Adjust the elevation to move the star down if it travels down. Repeat for at least 5 minutes, or until there is no drift.
6. If you performed a significant elevation adjustment (several degrees or more), go back and verify the azimuth; otherwise, you are finished. With a little practice, you should be able to finish the technique before the end of twilight. Experiment with it in your backyard until you’re confident. For declinations between +70 and -70 degrees, I found this approach to be precise enough for astrophotographs lasting up to 3 hours for small fields (less than 1 degree) and up to 2 hours for bigger fields (up to 5 degrees). For longer exposures and closer to the poles, a photographic polar alignment approach applicable exclusively to permanent installations may be necessary.
7. It should be noted that the star cannot wander at all for 5 minutes in order to reach the exposure periods specified above. If the drift is measured by bisecting a star with a line in an illuminated eyepiece, the star must remain bisected for the whole 5 minutes. Field rotation will begin to sneak into lengthy exposures if the star has migrated as little as half its diameter, according to experience.
