Post by RobbW on Jul 14, 2010 8:43:06 GMT -6
***WARNING: Really long freaking post. I apologize in advance, but I am really frustrated by this issue. Thanks!***
Okay, now that I've got a properly working drive mount for my telescope, I really want to get this whole "polar alignment" thing down. For the life of me, I can't figure it out. In theory, it seems like it should be relatively simple. In practice, it turns out I'm a dolt!
First, I don't have a polar alignment scope in my mount. Nor is there any possible way to add one, which would make this task much easier. There just isn't a place to install an alignment scope; no hole in the polar axis. So, I'm relegated to performing this task by sight alone.
I have many questions about this procedure. Should the polar alignment be performed sighting along the polar axis of the mount, or by centering Polaris in the EP of my scope? I've tried it both ways, and neither seems to work. I've tried sighting along the polar axis using my laser pointer, and adjusting the azimuth (turning the whole mount in the tripod clockwise or counter-clockwise) until the laser line passes through Polaris as I rotate the laser up and down with it flat against the side of the polar axis.
Trying to adjust the altitude by sight using my laser is a little more difficult. I'm just not sure where to place my laser to make sure it is in line with the polar axis. I tried rotating my scope on the RA axis until it is horizontal, and the side of the drive box is facing up. I then place my laser flat on top of the drive box with it centered right over the polar axis. I adjust the altitude until the laser line passes through Polaris as I rotate the laser side to side.
Using this laser-sighting-along-the-polar-axis method does not seem to keep my scope tracking very well. I don't know if it's errors in where I'm placing my laser during the alignment or what. So, I try aligning Polaris directly in the center of my EP instead. I would think doing the alignment through the EP should be sufficiently accurate, but it doesn't seem to work either. Of course, part of that problem may be making sure that both the OTA and the RA axis are directly lined up with the polar axis of the mount while I perform this procedure. I'm sure I'm probably slightly out-of-line on one or both of the axes, and that probably throws the whole alignment off.
Without having a polar alignment scope installed in my mount, which of the two methods above SHOULD be more accurate? I've made sure that my tripod and base are as level as I can possibly get them using the bubble level built into the tripod.
I realize that aligning on Polaris still doesn't technically make my scope polar aligned, but it should be close enough to keep a target within my field of view over the course of several minutes, right? It should give me a good start, and then I should be able to use the drift method to more accurately align my scope, right?
Speaking of the drift method, which Joe posted a very good video about in another of my threads, I can't seem to get that to work either. Following the instructions in the video, I chose a star rising in the eastern sky and centered on it in order to finely adjust my altitude. The video states that if the eastern star seems to rise in the EP while the mount is tracking, then the altitude is too low and should be raised. If the star seems to fall in the EP, then the altitude is too high and should be lowered. Unfortunately, I'm still very much a newb with my scope, but I do remember that when using a reflecting scope, the image projected in the EP is both upside-down and reversed, right? So that would mean that if the star appears to be falling in the EP, it actually means that it is rising, correct? And vice versa.
So, after doing a rough polar alignment on Polaris, I then centered a star in my EP that was low on the eastern horizon. Over the course of a few minutes, the star appeared to fall in my EP, which on a reflecting scope means that it was actually rising. So, following the video instructions, this meant my altitude was too low. I raised it a bit and performed the same procedure with the same result. The star keeps indicating that my altitude is too low.
After what seemed like a bazillion adjustments raising my altitude, the star kept falling in my EP. I thought that maybe I was wrong about the image in my EP being opposite of what the video was demonstrating. So, as an experiment, I decided to keep lowering my altitude until I stared seeing the star rise in my EP in relation to the movement of the drive mount. I kept lowering the altitude, centering the eastern star, and watching it. Each time, the star kept falling in my EP no matter how much I lowered my altitude. After a bazillion more adjustments and the star still falling, I took out my red flashlight and checked the altitude markings on my mount. The altitude was now reading 36 degrees. Obviously, that was way lower than what it should be for my location, which should be about 42 degrees.
So, I started going in the opposite direction again, repeating all the same steps and raising my altitude until I got to 45 degrees. Obviously, 45 is way too high for my location, but the damned star was still falling in my EP! What the hell is going on with this? How can the star keep falling in my EP regardless if my altitude is way high or way low? This doesn't make sense!
So, I gave up on aligning my scope for the night and resolved to manually adjusting the position of targets in my EP as they drifted. I had already spent more than an hour trying to align this stupid thing on an eastern star, and I was losing valuable viewing time. I figured I would try to enjoy the rest of the night actually looking at objects and pose my questions on this forum. Any help would be greatly appreciated!!!
Okay, now that I've got a properly working drive mount for my telescope, I really want to get this whole "polar alignment" thing down. For the life of me, I can't figure it out. In theory, it seems like it should be relatively simple. In practice, it turns out I'm a dolt!
First, I don't have a polar alignment scope in my mount. Nor is there any possible way to add one, which would make this task much easier. There just isn't a place to install an alignment scope; no hole in the polar axis. So, I'm relegated to performing this task by sight alone.
I have many questions about this procedure. Should the polar alignment be performed sighting along the polar axis of the mount, or by centering Polaris in the EP of my scope? I've tried it both ways, and neither seems to work. I've tried sighting along the polar axis using my laser pointer, and adjusting the azimuth (turning the whole mount in the tripod clockwise or counter-clockwise) until the laser line passes through Polaris as I rotate the laser up and down with it flat against the side of the polar axis.
Trying to adjust the altitude by sight using my laser is a little more difficult. I'm just not sure where to place my laser to make sure it is in line with the polar axis. I tried rotating my scope on the RA axis until it is horizontal, and the side of the drive box is facing up. I then place my laser flat on top of the drive box with it centered right over the polar axis. I adjust the altitude until the laser line passes through Polaris as I rotate the laser side to side.
Using this laser-sighting-along-the-polar-axis method does not seem to keep my scope tracking very well. I don't know if it's errors in where I'm placing my laser during the alignment or what. So, I try aligning Polaris directly in the center of my EP instead. I would think doing the alignment through the EP should be sufficiently accurate, but it doesn't seem to work either. Of course, part of that problem may be making sure that both the OTA and the RA axis are directly lined up with the polar axis of the mount while I perform this procedure. I'm sure I'm probably slightly out-of-line on one or both of the axes, and that probably throws the whole alignment off.
Without having a polar alignment scope installed in my mount, which of the two methods above SHOULD be more accurate? I've made sure that my tripod and base are as level as I can possibly get them using the bubble level built into the tripod.
I realize that aligning on Polaris still doesn't technically make my scope polar aligned, but it should be close enough to keep a target within my field of view over the course of several minutes, right? It should give me a good start, and then I should be able to use the drift method to more accurately align my scope, right?
Speaking of the drift method, which Joe posted a very good video about in another of my threads, I can't seem to get that to work either. Following the instructions in the video, I chose a star rising in the eastern sky and centered on it in order to finely adjust my altitude. The video states that if the eastern star seems to rise in the EP while the mount is tracking, then the altitude is too low and should be raised. If the star seems to fall in the EP, then the altitude is too high and should be lowered. Unfortunately, I'm still very much a newb with my scope, but I do remember that when using a reflecting scope, the image projected in the EP is both upside-down and reversed, right? So that would mean that if the star appears to be falling in the EP, it actually means that it is rising, correct? And vice versa.
So, after doing a rough polar alignment on Polaris, I then centered a star in my EP that was low on the eastern horizon. Over the course of a few minutes, the star appeared to fall in my EP, which on a reflecting scope means that it was actually rising. So, following the video instructions, this meant my altitude was too low. I raised it a bit and performed the same procedure with the same result. The star keeps indicating that my altitude is too low.
After what seemed like a bazillion adjustments raising my altitude, the star kept falling in my EP. I thought that maybe I was wrong about the image in my EP being opposite of what the video was demonstrating. So, as an experiment, I decided to keep lowering my altitude until I stared seeing the star rise in my EP in relation to the movement of the drive mount. I kept lowering the altitude, centering the eastern star, and watching it. Each time, the star kept falling in my EP no matter how much I lowered my altitude. After a bazillion more adjustments and the star still falling, I took out my red flashlight and checked the altitude markings on my mount. The altitude was now reading 36 degrees. Obviously, that was way lower than what it should be for my location, which should be about 42 degrees.
So, I started going in the opposite direction again, repeating all the same steps and raising my altitude until I got to 45 degrees. Obviously, 45 is way too high for my location, but the damned star was still falling in my EP! What the hell is going on with this? How can the star keep falling in my EP regardless if my altitude is way high or way low? This doesn't make sense!
So, I gave up on aligning my scope for the night and resolved to manually adjusting the position of targets in my EP as they drifted. I had already spent more than an hour trying to align this stupid thing on an eastern star, and I was losing valuable viewing time. I figured I would try to enjoy the rest of the night actually looking at objects and pose my questions on this forum. Any help would be greatly appreciated!!!
