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Equipment Discussions >> Mounts

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wargrafix
sage


Reged: 04/10/13

Loc: Trinidad
weird issue...
      #6316707 - 01/16/14 02:52 PM

Hi all. I did a test setup for my weekend session and encountered an issue. My yard has a bit-of a slope. Not very steep though. When I did my 2 star alignment + 1 and then polar align. Repositioned the mount using the handset. When I started searching, my mount always lands a little to the left (if looking through the finderscope)

So very very odd. If I use the handset and center it, the object will stay in the eyepiece just fine. What gives?


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Falcon-
Post Laureate
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Reged: 09/11/09

Loc: Gambier Island, BC, Canada
Re: weird issue... new [Re: wargrafix]
      #6316753 - 01/16/14 03:10 PM

You might try adding more alignment stars. I found that the go-to accuracy increased dramatically when I went 2+4 instead of 2+1.

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dragonslayer1
scholastic sledgehammer


Reged: 02/25/12

Loc: SLC, UT
Re: weird issue... new [Re: Falcon-]
      #6316846 - 01/16/14 04:04 PM

This is what I wonder about, did you polar align moving the mount or with the handset? Kasey
" When I did my 2 star alignment + 1 and then polar align. Repositioned the mount using the handset."


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guyroch
Vendor (BackyardEOS)
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Reged: 01/22/08

Loc: Under the clouds!
Re: weird issue... new [Re: dragonslayer1]
      #6316893 - 01/16/14 04:33 PM

You always polar align the mount with the adjustment bolts on the mount, not the handset.

Remember that polar alignment is the act of aligning the mount with the pole so this implies adjusting the mount.

Hope this helps,

Guylain


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guyroch
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Reged: 01/22/08

Loc: Under the clouds!
Re: weird issue... new [Re: guyroch]
      #6316897 - 01/16/14 04:34 PM

Oh, is your mount levelled? Make sure the mount is levelled on that slope yard before attempting any type of polar alignment.

Guylain


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Falcon-
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Reged: 09/11/09

Loc: Gambier Island, BC, Canada
Re: weird issue... new [Re: guyroch]
      #6317274 - 01/16/14 07:53 PM

Quote:

You always polar align the mount with the adjustment bolts on the mount, not the handset.




dragonslayer1 might have meant to ask if the handset built in ASPA feature was used.


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wargrafix
sage


Reged: 04/10/13

Loc: Trinidad
Re: weird issue... new [Re: Falcon-]
      #6318003 - 01/17/14 07:59 AM

Wow, thanks all. Let me see if I can address it in steps.

I am going to put the mount out tonight,its friday and skies look promising.I will try adding a few more calib stars tonight. the south to north part of my driveway is level, the slight incline is road (east) to the property (west). Should I raise a tripod leg to balance it?

I used the handset to do the aspa feature. I will try to use the adjustment bolts. weird question though if the star moves while I am doing the adjustment, what should I do? Or will the star stay while the the adjustments are being made?

My GOTO has been getting better, but the fine points of getting everything lined up for astrophotography is the final challenge. I too photos and hope to convert to jepg to start posting. I am getting annoyed with not having posted any stuff here yet. You all help alot and I really want to give back.


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guyroch
Vendor (BackyardEOS)
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Reged: 01/22/08

Loc: Under the clouds!
Re: weird issue... new [Re: wargrafix]
      #6318079 - 01/17/14 08:56 AM

Quote:

Should I raise a tripod leg to balance it?




Absolutely. If your mount in not leveled to begin with is like running a marathon with crutches.

The best way to leveled the mount, I find, is to remove the mount's head from the tripod and place a level on the tripod where the head would go. Then adjust the tripod legs to get the tripod leveled. Once it's leveled add the mount head back on the tripod. If you place your mount relatively at the same place from night to night just don't touch the tripod leg adjustment you just made and your tripod will be leveled each night as-is

Guylain


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wargrafix
sage


Reged: 04/10/13

Loc: Trinidad
Re: weird issue... new [Re: guyroch]
      #6318226 - 01/17/14 10:08 AM

Hmm, I am excited to try it out. I need to ask though, if the balanced was off along east to west, shouldn't the object be off up or down in the finderscope, not left or right ie north south?

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WadeH237
Pooh-Bah


Reged: 02/24/07

Loc: Snohomish, WA
Re: weird issue... new [Re: guyroch]
      #6318237 - 01/17/14 10:12 AM

It's important to understand the difference between "polar alignment" and "alignment" and how it affects things.

Polar alignment is a physical adjustment of the mount so that the RA axis is parallel with Earth's rotational axis. You do this on a Celestron mount with the "All Star Polar Alignment" routine. It does not matter if the mount is level or not, but it may make the process a bit easier. If your polar alignment is off, it will affect the mount's tracking. A polar misalignment will not affect goto. The mount is capable of doing accurate gotos even if the polar alignment is far off (it just won't track the object well after pointing to it).

The 2 star alignment that you do through the hand controller is how you sync the mount's internal map of the sky to the actual sky. The accuracy of this alignment will dramatically affect goto performance. It does not affect tracking (since that is related to polar alignment).

After the 2 star alignment, you may optionally do up to 4 calibration stars. Strictly speaking, this is very different than the 2 alignment stars. These 4 stars don't sync the sky to the mount. Rather, they help the mount characterize mechanical error. If you have a perfectly orthogonal system (nobody does), then this step would be unnecessary. By adding these stars, you help the mount to compensate for issues like slight misalignment between where the telescope optics point and where the mount's RA axis points. Personally, I always do 4 stars. It only takes a minute and it gets the best results. The calibration stars have a large affect on pointing accuracy (but not tracking).

In doing both the 2 star alignment and the 4 calibration stars, technique is very important. My experience has been that most of the problems that people encounter with pointing boils down to this.

By far, the most important thing is to make sure that when you look in the eyepiece, you are centering the star that you think you are. For example, if the hand controller wants you to center Alkaid (the end of the big dipper handle), make sure that you are not actually seeing Mizar (the middle star in the big dipper handle) in the eyepiece. The critical thing here is to make sure that your finder scope (or, even better, get a Telrad) and your telescope are pointing exactly the same. To ensure this, go out before dark and point the telescope at something unique on the horizon. The farther away, the better. A tower or an unusual tree top makes a good target. Then, after the scope is pointed at the object, adjust your finder scope (or Telrad, etc.) so that the object is centered there, too.

Note that based on the pointing performance described here, where the object is always in the eyepiece, but off center, it is pretty certain that the correct stars were centered. I've just included the above step for completeness.

Ok, so now you have the correct star in the eyepiece. The next thing is to make sure that you center it properly. First off, an eyepiece with an illuminated reticule is best because you can easily see the exact center of the eyepiece. If you don't have one, then a good tip is to defocus the star so that it's a big donut (or circle if you have a refractor). It's much easier for your eye to identify centering of a big donut than it is for a focused spot.

Finally, now that you have a way to accurately center the star, you need to make sure that you do it consistently every time. And for a Celestron mount, there is one right way. Specically, you must complete the centering process with only the "up" and "right" buttons on the controller. If your last button press is either "down" or "left", you will get some pointing error. The reason for this is that the mount has some mechanical slop (backlash) in the gears. To make sure that you take up this backlash in the same way that the mount does when it points, you need to do it the way that I describe. To do this, I always begin the centering process by hitting "down" and "left" into the star is on the edge of the eyepiece and needs to move up and right. When you do this, you may see the effects of backlash as either a delay when the star moves, or some jumpiness when it first starts to move. The reason that I go down and left all the way to the edge is to make sure that all the backlash is taken up. Then, you can use the "up" and "right" buttons to center the star. If you go past center, then go all the way back down and left to the edge and do it again. Note that it's often helpful to go down to a really slow move rate to make this easier.

One final note is that I mentioned polar alignment first because it was easiest to describe. When you actually do this, the order of operation will be:

1. Set up the mount

2. Turn it on and enter date, time, etc. Different Celestron mounts have different steps here. Note that the date, time and location are not critical for pointing at deep sky objects. If the date, time and location are off, it will affect pointing at solar system objects and it will affect how close the mount gets when it points to where it thinks the first alignment star is. Even if that initial pointing is far off, the alignment will work fine as long as you center the correct star.

3. Do the 2 star alignment

4. Do all 4 calibration stars

5. Use goto to point at a star in the southern sky. This will be the star that you use for the ASPA routine. I like to use a star somewhat near the southern sky near the celestial equator. I believe that you ideally want a star that's 90 degrees away from the North Celestial Pole. But it's not critical. In the summer, I often use Antares or Altair, etc.

6. Do the ASPA routine.

At the conclusion of the ASPA routine, the mount is ready to use. Some people like to power it off and repeat steps 1 through 4. I've found that if you've carefully done everything as I described above, this is unnecessary. Once ASPA is done, I just use the mount.

I hope that this helps.


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wargrafix
sage


Reged: 04/10/13

Loc: Trinidad
Re: weird issue... new [Re: WadeH237]
      #6318257 - 01/17/14 10:22 AM

That was alot of help Wade. :-)

I should say that I do the step you outlined and I have a measure of success. The problem occurs where I am finally going to the target, the target is a bit off, most of the time to the left of the finderscope, or best case, on the left of the eyepiece. if I use the handset and I center it, it tracks fine. all well and good for bright targets but for dim ones, you can see where this is an issue. Its very very weird.


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WadeH237
Pooh-Bah


Reged: 02/24/07

Loc: Snohomish, WA
Re: weird issue... new [Re: wargrafix]
      #6318471 - 01/17/14 12:00 PM

Pointing on the Celestron mounts is very good, but not perfect. I assume that you are using your 9.25" scope. If you are using a high power eyepiece, it may be somewhat normal for the object to be off center, or maybe out of view if high enough power.

You have a couple of options to try and improve it.

First off, if you sync on a bright object in the area you are viewing, it can noticeably increase pointing accuracy. Also, keep in mind that the ASPA routine includes doing a sync on the star that you used for polar alignment. It's possible, if that star is in a different part of the sky, that the mount is still sync'ed there and this could be affecting your results. When in doubt about this, just do an unsync.

Finally, for hunting really dim objects that are at the edge of detectability, I usually use the "Precise Goto" feature. This will have you center a nearby star and then it will do a special slew from that object to the desired target. I've never known it to miss.

-Wade


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Peter in Reno
Postmaster
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Reged: 07/15/08

Loc: Reno, NV
Re: weird issue... new [Re: WadeH237]
      #6318514 - 01/17/14 12:17 PM

Keep in mind that mirrors in SCT scopes flop when slewing from one object to another. For example, I center/sync a star with the findersccope and the main OTA. Then slew to another object far away, the star would be center in finderscope but in in main OTA. That's because the SCT's mirror shifted (flopped) during slews. I see it all the time.

Like Wade said, during ASPA it does a sync on a "polar" star and after you are done with ASPA, you should "unsync" before slewing to objects. I don't know why Celestron engineers left the "sync" enabled after ASPA.

Also, I think you should re-do the star alignments (2 + 4) after ASPA because you moved the mount by adjusting Alt and Az controls. This can guarantee better GoTos. It worked well for me for my previous CPC0800. Don't forget to "unsync" first before re-running star alignments as explained in Celestron manual.

Like Wade said about Precise GoTo, it's an awesome feature.

Peter


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dawziecat
Carpal Tunnel
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Reged: 10/20/10

Loc: Rural Nova Scotia
Re: weird issue... new [Re: guyroch]
      #6318623 - 01/17/14 01:12 PM

Quote:

Oh, is your mount levelled? Make sure the mount is levelled on that slope yard before attempting any type of polar alignment.

Guylain




I was faced with doing some imaging in this same situation. I took pains to level the mount . . . but not the chair.

"Don't fall ouut'a ^&*$@ chair!" I said to myself.

Yep. Fell outt'a my chair on the very first night!


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rmollise
Postmaster
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Reged: 07/06/07

Re: weird issue... new [Re: guyroch]
      #6318737 - 01/17/14 01:56 PM

Quote:

Oh, is your mount levelled? Make sure the mount is levelled on that slope yard before attempting any type of polar alignment.

Guylain




Level makes no difference for polar alignment.

OP: Two things right off the bat... Not sure what you mean by "repositioned the mount with the handset," but if you mean you did the polar alignment that way, that is not how you do it. The final part of the AllStar alignment requires you to move the mount with the mount altitude and azimuth adjusters. Also, always do at least three calibration stars for best results.

Edited by rmollise (01/17/14 02:00 PM)


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wargrafix
sage


Reged: 04/10/13

Loc: Trinidad
Re: weird issue... new [Re: rmollise]
      #6318815 - 01/17/14 02:35 PM

Ok, you guys got me super excited here. I am spotting a few things to do differently. I strongly suspect that i didn't un-sync and this could result in it getting close to the target but missing a bit.

A question I asked earlier might help me. Obviously, in the moving of the alt-az knobs a little time will pass, how o ensure that i maintain the star on target?


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WadeH237
Pooh-Bah


Reged: 02/24/07

Loc: Snohomish, WA
Re: weird issue... new [Re: wargrafix]
      #6318960 - 01/17/14 03:47 PM

Quote:

Obviously, in the moving of the alt-az knobs a little time will pass, how o ensure that i maintain the star on target?




I'm sorry. I don't understand the question.


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rmollise
Postmaster
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Reged: 07/06/07

Re: weird issue... new [Re: wargrafix]
      #6318968 - 01/17/14 03:52 PM

Quote:



A question I asked earlier might help me. Obviously, in the moving of the alt-az knobs a little time will pass, how o ensure that i maintain the star on target?




Just follow the instructions. At the end of the AllStar procedure, the mount will slew off the star. Center it with the alt-az adjusters and...you...are...done.


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Peter in Reno
Postmaster
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Reged: 07/15/08

Loc: Reno, NV
Re: weird issue... new [Re: rmollise]
      #6319021 - 01/17/14 04:15 PM

Quote:

Quote:

Oh, is your mount levelled? Make sure the mount is levelled on that slope yard before attempting any type of polar alignment.

Guylain




Level makes no difference for polar alignment.




That's true but ASPA likes the mount to be reasonably level so that the mount will most likely be polar aligned on the first try. The more unlevel the mount is the more likely to run two or more iterations of ASPA. There was a very long thread about this and Celestron responded back to me saying that it's better for mount to be leveled for ASPA.

But if you polar align using old school drift alignment, the it makes absolutely no difference whether the mount is leveled or not. It will probably take longer and more iterations to get it polar aligned than if the mount was initially level.

This is what Celestron said to me:

"It's kind of a yes and no answer that is rather subjective. To get a proper ASPA, you do not have to be perfectly level. This is where it gets somewhat subjective though. You can't get a good polar alignment out of a severely off balance tripod. The further away from level that you get, the worse your polar alignment will get. We've had many users in the past who will set up their tripod on a slight hill and not spend much time leveling the tripod and get great results. So it really depends alot of how off balance the tripod is."

Peter


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guyroch
Vendor (BackyardEOS)
*****

Reged: 01/22/08

Loc: Under the clouds!
Re: weird issue... new [Re: rmollise]
      #6319024 - 01/17/14 04:16 PM

Quote:

Level makes no difference for polar alignment.




I disagree.

Guylain


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WadeH237
Pooh-Bah


Reged: 02/24/07

Loc: Snohomish, WA
Re: weird issue... new [Re: guyroch]
      #6319114 - 01/17/14 05:03 PM

Quote:

Quote:

Level makes no difference for polar alignment.




I disagree.

Guylain




Polar alignment is achieved when the mount's RA axis is perfectly parallel to Earth's rotational axis. It makes no difference at all whether the mount is level or not. It could be hanging upside down from a (very steady) tree branch and still be polar aligned if that criteria is met.

The process of getting the mount polar aligned can be made somewhat easier or more difficult, depending on whether the mount is level or not.

The reason for this is that your are adjusting the mount in altitude and azimuth. If the mount is perfectly level, a change in altitude does not affect azimuth and vice-versa. If the mount is not level, then a change in altitude will affect azimuth to some degree, and a change in azimuth will affect altitude to some degree.

This does not preclude you from achieving polar alignment. You either need to anticipate and account for the movement in the other axis, or you could do additional iterations of whatever method you are using to keep reducing the amount of error in the other adjustment.

It's this latter part that is the reason to get the mount level. But it's not an all or nothing deal. If the mount is reasonably close to level, then you'll have no problems. If the mount is leaning over 45 degrees, then you'll have a harder time of it.

I think that the main thing to remember is that there is not a whole lot to be gained by spending a huge amount of effort leveling the mount. Close is good enough.

This is especially true on a mount like the CG5 mentioned in this thread. The altitude and azimuth adjustments are so coarse, that it's impossible to make really tiny adjustments. I have many Celestron mount, including a couple of CG5s. I would say that it's impossible to get closer than say within 15 arc minutes of the NCP (unless you get lucky) just because of this.

Finally, everything that I've said here is really splitting hairs. For visual use, you can be a couple of degrees off the NCP and it won't result in problematic drift. Even for imaging, as long as you're guiding, you'll be fine with one iteration of ASPA.


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rmollise
Postmaster
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Reged: 07/06/07

Re: weird issue... new [Re: guyroch]
      #6319117 - 01/17/14 05:06 PM

Quote:

Quote:

Level makes no difference for polar alignment.




I disagree.

Guylain




You can disagree all you want. A few minutes considering the geometry of the situations shows you are clearly wrong.


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rmollise
Postmaster
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Reged: 07/06/07

Re: weird issue... new [Re: rmollise]
      #6319124 - 01/17/14 05:09 PM

I have been polar aligning the CG5 for years. It is more than possible to get the mount right on the money with the adjusters. I can easily get the AllStar star dead in the crosshairs of the Mallincam which yields fairly high "magnification." Similarly, it's no problem to drift align the mount to a point way closer than 15'...

The main caveat? Be careful tightening down the azimuth, as that can throw you back off.


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rmollise
Postmaster
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Reged: 07/06/07

Re: weird issue... new [Re: Peter in Reno]
      #6319138 - 01/17/14 05:20 PM

Quote:



"It's kind of a yes and no answer that is rather subjective. To get a proper ASPA, you do not have to be perfectly level. This is where it gets somewhat subjective though. You can't get a good polar alignment out of a severely off balance tripod. The further away from level that you get, the worse your polar alignment will get. We've had many users in the past who will set up their tripod on a slight hill and not spend much time leveling the tripod and get great results. So it really depends alot of how off balance the tripod is."






I have no idea where this guy was going with the business about "off balance tripods." I don't see that this has much/anything to do with level. The only thing being level can do for you is make it a little easier to center the stars in some instances. That is all.


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WadeH237
Pooh-Bah


Reged: 02/24/07

Loc: Snohomish, WA
Re: weird issue... new [Re: rmollise]
      #6319172 - 01/17/14 05:36 PM

Quote:

I have been polar aligning the CG5 for years. It is more than possible to get the mount right on the money with the adjusters. I can easily get the AllStar star dead in the crosshairs of the Mallincam which yields fairly high "magnification." Similarly, it's no problem to drift align the mount to a point way closer than 15'...

The main caveat? Be careful tightening down the azimuth, as that can throw you back off.




You may be right. I was thinking about the CGE's azimuth adjustment, which is a pain to work with. Even when drift aligning the mount, it's really hard to get dialed in perfectly.

Still, even on the CG5, if I shutdown the mount and redo the 2+4 stars, then query the polar alignment, it shows errors typically in that neighborhood. I've never tried to drift align a CG5 to compare to what the hand controller reports.


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Peter in Reno
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Reged: 07/15/08

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Re: weird issue... new [Re: rmollise]
      #6319177 - 01/17/14 05:40 PM

This thread is about Celestron ASPA, not polar alignment in general (i.e. drift alignment where leveling mount is irrelevant). I am talking about ASPA on the FIRST TRY for a badly level mount. If you don't agree, kindly try this experiment yourself.

Celestron meant unlevel tripod/mount when they said off balance tripod because I mentioned unlevel mount when I sent them the message.

Peter

Edited by Peter in Reno (01/17/14 06:03 PM)


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rmollise
Postmaster
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Reged: 07/06/07

Re: weird issue... new [Re: Peter in Reno]
      #6319203 - 01/17/14 06:07 PM

That's not what he said, however. He referred to "unbalanced" at least twice in his reply to you. I have _never_ found being off level to have any effect on go-to or ASPA alignment.

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Peter in Reno
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Reged: 07/15/08

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Re: weird issue... new [Re: rmollise]
      #6319218 - 01/17/14 06:24 PM

To all others, just level Celestron NexStar based mount as well as possible for ASPA to work well on the first try. It's not difficult to level the mount.

For interested reading about the thread regarding to ASPA and level mount, see:

ASPA and level

The conclusion is at (page 23) near the end of this incredibly long thread.

Peter


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wargrafix
sage


Reged: 04/10/13

Loc: Trinidad
Re: weird issue... new [Re: Peter in Reno]
      #6319432 - 01/17/14 08:55 PM

Wow. Thread really expanded in the last few hours. First the bad news. Clouds. Not even a large mass. Just enough to make things difficult. The answe to my question is the star will hold while I center it. My yard is a slight incline so it should be workable. Thank you everyone. I hope the discussion continues. I am sure its helping others. :-)

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guyroch
Vendor (BackyardEOS)
*****

Reged: 01/22/08

Loc: Under the clouds!
Re: weird issue... new [Re: rmollise]
      #6319440 - 01/17/14 09:00 PM

Quote:

Quote:

Quote:

Level makes no difference for polar alignment.




I disagree.

Guylain




You can disagree all you want. A few minutes considering the geometry of the situations shows you are clearly wrong.




Well, if that is case Rod we will have to agree to disagree. I have no dog in this fight.

While technically leveling a GEM is not an absolute necessity, getting the mount setup as level as possible can save you time and frustration. A GEM can be out of level and still be polar aligned, once the R.A. axis is aligned and the declination axis set to the correct latitude the mount is correctly polar aligned, level or not. Once the mount is properly calibrated with ASPA it knows where the pole is and will perform good gotos, if not perfect most of the time. But for ASPA to tell the user how to adjust the mount in the first place it must start from a known geometry position, that position is a level mount. You can choose to ignore this, it makes to difference to me. I don't mean any disrespect by saying so, but you are wrong too. The initial geometry the mount assumes is a level mount, so saying the mount not needing to be levelled to polar align your mount is false; it does play a role!

I guess I do know a thing or two about geometry after all; sorry to disappoint you!

It is just that getting to the correct alignments when your GEM is out of level takes more time & work than starting out level. Leading a beginner in a direction where a level mount is irrelevant is not good advice IMO.

My 2 cents, and I'm out of this thread. It seems like simple advice of starting off with a level mount is used and twisted in ways that it was not intended to, that is too bad.

@wargrafix: Save yourself some time, trouble, frustration, and take the extra 2 minutes to start with your mount as level as possible. Two minutes is all it takes to remove a variable out of the equation that could lead to frustration.

Good luck!

Guylain


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TCW
professor emeritus


Reged: 11/05/13

Re: weird issue... new [Re: rmollise]
      #6319700 - 01/18/14 12:14 AM

How can leveling not help in accurate polar alignment? If your mount is set for your latitude then being out of level will guarantee it is not pointing at the pole even if it is pointing due north. The way I see it, it is a physical necessity. If it is not level then you would have to alter the latitude setting to point to the celestial pole.

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jrcrillyAdministrator
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Re: weird issue... new [Re: TCW]
      #6319717 - 01/18/14 12:29 AM

Quote:

If it is not level then you would have to alter the latitude setting to point to the celestial pole.




You always have to alter the elevation setting. Even if the base were perfectly level and the mount perfectly square (neither of which is possible) the latitude scale has nowhere near the resolution required to set the elevation with sufficient accuracy.


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TCW
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Reged: 11/05/13

Re: weird issue... new [Re: jrcrilly]
      #6319725 - 01/18/14 12:39 AM

The point is if you have an accurate latitude setting and the mount is level then all you have to do is change one plane to achieve alignment. Accurately leveling the mount only takes a few seconds if you use a decent level. Any latitude adjustment would be very small. As a builder I wince to hear someone say level makes no difference. Leveling should save time at the very least.

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dragonslayer1
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Re: weird issue... new [Re: TCW]
      #6320106 - 01/18/14 10:01 AM

There was a mile long thread on leveling for ASPA a while back that covered EVERY SINGLE aspect of it, I would refer all back to that.. I wonder if the OP got it working right, hopefully he will follow up, Kasey

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rmollise
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Re: weird issue... new [Re: Peter in Reno]
      #6320178 - 01/18/14 10:47 AM

Quote:

To all others, just level Celestron NexStar based mount as well as possible for ASPA to work well on the first try. It's not difficult to level the mount.






Nope, but not necessary. If you are worried about level, level by eye is fine.

I've used the AllStar routine many times and have never given a moment's thought to leveling...and yet...AllStar works!

Edited by rmollise (01/18/14 10:56 AM)


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rmollise
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Re: weird issue... new [Re: guyroch]
      #6320180 - 01/18/14 10:49 AM

Quote:



I guess I do know a thing or two about geometry after all; sorry to disappoint you!




Maybe you do, maybe you don't. I have no way of knowing. If you do, you haven't thought this through very well.


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wargrafix
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Re: weird issue... new [Re: TCW]
      #6320210 - 01/18/14 11:01 AM

Tonight I hope the weather will cooperate. I agree levelling will certainly help but the slope is maybe 5 degrees so its not too bad. If I change the latitude scale if need be perhaps this will improve the accuracy. I guess the mechanical nature of these setups rely heavily on the levelling but if that isn't possible then workarounds need to be made.

Anyone every had the slew to target after doing a setup and pole alignment with no levelling still land not in the finder's cross hairs?


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John608
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Re: weird issue... new [Re: wargrafix]
      #6320300 - 01/18/14 11:38 AM

Forget this issue of level it doesn't matter except that if you are on tilted ground you may want to adjust the tripod for it to keep your mount from being too easy to tip over on one side. Do the 2+4 alignment then do the ASPA making sure you follow the instructions in the manual. Your final moves to center your star will involve moving the mount in altitude using the altitude adjusters and in azimuth using the two azimuth adjusters. After that unsync the mount then check your first two alignment stars, if they are significantly off you can replace one or both with the same or another star. The process is really quite simple once you get used to it, if you are having problems it is NOT that your mount in not level, it is something else, most likely not following the procedure correctly. Good Luck!

John. G


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guyroch
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Re: weird issue... new [Re: rmollise]
      #6320333 - 01/18/14 11:56 AM

Quote:

Quote:



I guess I do know a thing or two about geometry after all; sorry to disappoint you!




Maybe you do, maybe you don't. I have no way of knowing. If you do, you haven't thought this through very well.






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wargrafix
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Re: weird issue... new [Re: John608]
      #6320338 - 01/18/14 11:59 AM

Ah thank you. Actually the slope is very slight. Zero chance of tipping over, thankfully. :-)

I am assuming that after I align, I then unsync and can restart the alignment process. Or just slew to and object say m67 and if its off I might need to realign?


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freestar8n
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Re: weird issue... new [Re: rmollise]
      #6320426 - 01/18/14 12:39 PM

Quote:

A few minutes considering the geometry of the situations shows you are clearly wrong.




Rod -

It is very obvious that some consideration of the geometry points to level not mattering to polar alignment.

It is *not* obvious that All Star Polar Alignment *cannot be done* without assuming the mount is level - and that level matters - but it is true.

This is what the long thread was all about - and I believe most people were eventually led to realize that level does matter.

The point isn't that "level matters to polar alignment." The point is that "level matters to the all star polar alignment procedure."

The fly in the ointment of the geometry is the inherent transformation from the polar axis error in sky coordinates, to the alt-az motions of the mount. The fact that this requires having the mount be level, or in some known orientation, is not obvious - but it is completely true.

ASPA has to assume the mount is level or there will be error in the final alignment. For small amounts off level it will be a small error - but for large errors in pier tilt or time or lat/long - the error can be huge.

So people should definitely have the mount pretty well level when they use ASPA. They don't have to go nuts about it - but decently level and decently accurate lat/long/time are all important.

If they *don't* use ASPA and they use a polar scope or something - they can have the whole thing in some crazy tilted state and it will work fine - but that isn't ASPA.

Frank


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rmollise
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Re: weird issue... new [Re: freestar8n]
      #6320876 - 01/18/14 04:52 PM

Quote:



It is very obvious that some consideration of the geometry points to level not mattering to polar alignment.

It is *not* obvious that All Star Polar Alignment *cannot be done* without assuming the mount is level - and that level matters - but it is true.




But that's not obviously the opinion of Celestron given the reply from one of their people posted here. Further, I've, as I said, frequently completed AllStar very satisfactorily without worrying about leveling. Was my mount off level by 20 degrees? No, I can't say that, but I can say I didn't lay hands on a bubble level.


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wargrafix
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Re: weird issue... new [Re: freestar8n]
      #6320880 - 01/18/14 04:55 PM

Hmmm....I am by the inlaws so in need to wait until I arrive home. Question: if I use only east stars to align, would this throw off things..my2 stars are rigel and sirius. Calib is canupus pollux and castor and betelguze

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guyroch
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Re: weird issue... new [Re: wargrafix]
      #6320894 - 01/18/14 05:03 PM

Quote:

Hmmm....I am by the inlaws so in need to wait until I arrive home.




I'm sure your inlaws (and spouse) will understand and support your decision to leave now and attend to the important things



Guylain


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Peter in Reno
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Re: weird issue... new [Re: rmollise]
      #6320903 - 01/18/14 05:09 PM

You probably missed this part of Celestron's response:

Quote:

The further away from level that you get, the worse your polar alignment will get.




'nuff said.

Peter


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rmollise
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Re: weird issue... new [Re: Peter in Reno]
      #6320905 - 01/18/14 05:12 PM

Quote:

You probably missed this part of Celestron's response:

Quote:

The further away from level that you get, the worse your polar alignment will get.




'nuff said.

Peter




But he referred to "level" in terms of the tripod being off balance. 'Nuff said. Excelsior.


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rmollise
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Re: weird issue... new [Re: wargrafix]
      #6320907 - 01/18/14 05:13 PM

Quote:

Hmmm....I am by the inlaws so in need to wait until I arrive home. Question: if I use only east stars to align, would this throw off things..my2 stars are rigel and sirius. Calib is canupus pollux and castor and betelguze




If you leave off your calibration stars, your go-tos will not be as good, at least in areas far from the two alignment stars.


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freestar8n
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Re: weird issue... new [Re: rmollise]
      #6320954 - 01/18/14 05:33 PM

Quote:

But that's not obviously the opinion of Celestron given the reply from one of their people posted here.




Your original comment alluded to the geometry of the situation, and the long thread describes the fundamental geometry and mathematics of the process. It has nothing to do with the way it was implemented. It has to do with the fact that the adjustments are made in alt/az, and those axes have a specific orientation. I would be happy to explain it at any level if you are interested, but if you look at my figures at the beginning of the long thread - with an open mind - it might make sense.

If you are interested in the details of these things and how they work, then I encourage you to take a look. You cannot pre-move the mount in equatorial movements so that a user's subsequent alt-az motions will do the right thing - unless you know how those alt/az axes are oriented to the sky. To me - this should be obvious from the geometry of the transformations involved.

Frank


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jimbo728
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Re: weird issue... new [Re: guyroch]
      #6320967 - 01/18/14 05:40 PM

The CG 5 has a bubble level built in. Leveling provides consistency in your set up. If you are going to do AP, consistency in set up and balance will improve pointing accuracy.
If you must set up on a slope you really should adjust the tripod legs to level just to avoid a tip over.
No matter who is technically right on this one, it doesn't hurt to level the mount.
Good luck!
Jim


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wargrafix
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Re: weird issue... new [Re: jimbo728]
      #6321068 - 01/18/14 06:39 PM

Lol. If I was staying over, the mount would be out right now. But I have heard the bubble is not correct on the cg5. I will give it a try when I arrive home. So many possible outcomes. I hope to get the right one.

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dragonslayer1
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Reged: 02/25/12

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Re: weird issue... new [Re: jimbo728]
      #6321077 - 01/18/14 06:45 PM

Yes, you first try and get it aligned to polaris by sight when you set up your mount. Then do your 2+4 (2star align/ 4 star calibration) then go to a star on southern horizion, approx 60* and towards the west.
Select Polar Align/mount align; It will select the star you were just on and you center and align it and the mount will sync to it. Then when you accept you want polar align, the mount will move to where the star should be,,, Then you adjust the mount RA/DEC adj knobs to try and get it centered as best as possible.. Then when done exit polar align and unsync the star that was used. Then redo 4 calibration points and if go-to are not good enough, then power down and redo 2+4, Kasey


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wargrafix
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Re: weird issue... new [Re: dragonslayer1]
      #6321136 - 01/18/14 07:26 PM

I wish I can see polaris from where I setup but not so luck. Its compass and guesswork.

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dragonslayer1
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Re: weird issue... new [Re: wargrafix]
      #6321246 - 01/18/14 08:58 PM

Acompass is fine, Kasey

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rmollise
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Re: weird issue... new [Re: freestar8n]
      #6321257 - 01/18/14 09:07 PM

Quote:




If you are interested in the details of these things and how they work, then I encourage you to take a look. You cannot pre-move the mount in equatorial movements so that a user's subsequent alt-az motions will do the right thing - unless you know how those alt/az axes are oriented to the sky. To me - this should be obvious from the geometry of the transformations involved.

Frank




Thanks. But my observations are:

1. Level does not effect the go-to alignment.
2. Neither does is affect AllStar in any observable fashion.

Knowing that I do not need to have the mount precisely level is good enough for me.

Edited by rmollise (01/18/14 09:08 PM)


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guyroch
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Re: weird issue... new [Re: rmollise]
      #6321403 - 01/18/14 10:54 PM

Quote:

Quote:




If you are interested in the details of these things and how they work, then I encourage you to take a look. You cannot pre-move the mount in equatorial movements so that a user's subsequent alt-az motions will do the right thing - unless you know how those alt/az axes are oriented to the sky. To me - this should be obvious from the geometry of the transformations involved.

Frank




Thanks. But my observations are:

1. Level does not effect the go-to alignment.
2. Neither does is affect AllStar in any observable fashion.

Knowing that I do not need to have the mount precisely level is good enough for me.




Actually Rod your observations in this thread alone led you to make 2 strong statements against me. It is obvious (to me at least) that your observations are just that, your observations... yet you claimed geometry as a mean to defend your observed -practical- experience.

You are certainly entitled to defend your -practical- experience at face value (as should anybody), after all it is real experience you accumulated over the years. However, you should refrain (as should anybody) from making derogatory comments towards another member claiming anything but your observed experience. It is becoming very clear to me that you claimed geometry without having thought this through very well (note that I have used your wording).

You can read whatever you want into my comments, but know that I do not mean any disrespect. I truly mean that.

Like I said earlier, I have no dog in this fight.

Levelling your mount is, simply put, common sense. Case closed.

Guylain


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guyroch
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Re: weird issue... new [Re: guyroch]
      #6321409 - 01/18/14 11:01 PM

I suggest we leave all that behind us and bring the conversation back to the original intention of the OP.

He seems truly motivated in learning polar alignment and astronomy as a whole.

WE SHOULD BE EMBRACING THAT!

Regards,

Guylain


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freestar8n
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Re: weird issue... new [Re: guyroch]
      #6321443 - 01/18/14 11:26 PM

I think that the main thing for the OP to do is use more calibration stars for better goto accuracy and polar alignment. Using 3 calibration stars instead of 1 should improve things greatly.

Level, time, and lat/long do affect the all star polar alignment accuracy, but this sounds like a GoTo accuracy issue - and that shouldn't be affected by level, but it can be affected by using only one calibration star.

Frank


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rmollise
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Re: weird issue... new [Re: guyroch]
      #6321872 - 01/19/14 10:01 AM

Quote:



Actually Rod your observations in this thread alone led you to make 2 strong statements against me. It is obvious (to me at least) that your observations are just that, your observations... yet you claimed geometry as a mean to defend your observed -practical- experience.






Nope. Read my posts more carefully. I said that level has no effect on being able to polar align an equatorial mount. And it doesn't.

As for the AllStar alignment procedure, my observation is that _in my experience_ level, precise level anyway, anything beyond eyeballing has absolutely no effect on the procedure. I haven't made a study of this. But I can say that being somewhat off level doesn't do a thing to the accuracy of this polar alignment method OR to go-to accuracy.

I didn't make derogatory comments about anyone. Again, see if you can read my posts a little more carefully.

Edited by rmollise (01/19/14 10:13 AM)


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wargrafix
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Re: weird issue... new [Re: rmollise]
      #6321987 - 01/19/14 11:14 AM

Wow. I didn't mean to start anything negative here. Everyone here has been super helpful . There are a few issues I am trying to work around but I sincerely appreciate everyone's input. Lets try this another way. Please bear with me:

Last night was clear and then before coming outside. ...rain. :-(
I don't trust the bubble level on my mount. Before attaching mount to the tripod I made sure all 3 axis were dead level. Popped the mount and showed not level. I put my bubble level and it said level. Now this was on a level ground.
Obverving area is where the slight incline is and I will try the levelling for the sake of completeness. The issue which bugs me is the results are off north south and not east west where the incline exist.

I need to ask after leveling how much off the first alignment star is normally off? Also I have a very very stupid question. The dec cable has one end saying to dec motor, does it go to the dec area where the ota is or where the other cables are attached to.

A long read I know but I want you all to know that I am not only grateful but also more motivated than before. :-)


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dragonslayer1
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Re: weird issue... new [Re: wargrafix]
      #6322030 - 01/19/14 11:50 AM

Its like Rod said, eye balling it is close enough for level to find your problem. The first alignment star can be off a lot. When you get set-up, reset your settiungs to factory settings. thats in menu in handset. Then enter location timwe date time zone etc then start your 2+4 alignment, then polar align, Kasey

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John608
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Re: weird issue... new [Re: wargrafix]
      #6322050 - 01/19/14 12:05 PM

I have used an ASGT mount for many years and on all kinds of tilted surfaces and have never worried about level. I have had not problems any problems in aligning or in ASPA with the mount that could not be traced to other procedural errors I made. I am quite sure that LEVEL is NOT the source of your problems. Among the possibilities are the following:

Are your time, date, location entries accurate? Are your index marks lined up, and are they accurate? ASGT's are known for having inaccurately placed index marks. Are you doing a 2 + 4 alignment to start? Are your calibration stars on the opposite side of the meridian from your alignment stars? If your first alignment star was outside the field of view are you sure you ended up aligning the correct star? What sort of eyepiece are you using to do the alignment with? A medium to high power illuminated crosshair eyepiece is best. Are the Dec and RA axis locked properly? Are the azimuth locks, the tripod center bolt and the altitude bolts all tightened? Have you done the 'Calibrate Mount' procedure under 'Utilities' after a good 2+4 alignment (you only have to do this once)?

That's a long list and may not even be complete, but each of those things are critical to getting and holding an accurate alignment. A final note, the ASGT is NOT the most accurate mount in the world. It is not an Astro- Physics Mach 1. After a good alignment gotos should place stars within the field of a low power to medium power eyepiece. Gotos will likely NOT place objects in the center of a high power eyepiece. Tracking the object over time will depend on the accuracy of your polar alignment.

I hope this helps, I would spend less time fussing over levelling and more time reviewing and checking that you have followed all the procedures correctly. They are simple with a little practice. Good Luck!

John G


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rmollise
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Re: weird issue... new [Re: John608]
      #6322055 - 01/19/14 12:07 PM

Let me add, that even when everything is right vis--vis goto alignment, it is unrealistic to expect every object to be in the center of the eyepiece. OTOH, the VX and CG5 are remarkably good in this regard, even compared to much more expensive mounts. My mounts will place anything from one side of the sky to the other in a medium power eyepiece of 150x or so.

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jrcrillyAdministrator
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Re: weird issue... new [Re: dragonslayer1]
      #6322149 - 01/19/14 12:59 PM

C'mon, folks. The thread is about goto accuracy issues and there is (or should be) no controversy about whether a level mount OR polar alignment are relevant to that topic with this particular mount. The whole "ASPA depends on a level mount" thing has already been discussed exhaustively in a another thread. That thread has been linked to in this one so anyone who wants to see it can do so.

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wargrafix
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Re: weird issue... new [Re: dragonslayer1]
      #6322280 - 01/19/14 02:08 PM

Ohhhh. That is where I will start.
The dec cable question is much appreciated.


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wargrafix
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Re: weird issue... new [Re: wargrafix]
      #6322365 - 01/19/14 02:47 PM

I think the inability to use westerly suitable stars could be affecting my goto accuracy. I normally use my 25mm eyepiece. What drives me nuts is the first few will find well and then accuracy gets worse.

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rmollise
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Re: weird issue... new [Re: wargrafix]
      #6322429 - 01/19/14 03:20 PM

No. As long as you add calibration stars, using those stars will be fine. And, if possible use a crosshair eyepiece. I use a 12mm for alignment. ANYHOW...if you don't like using stars in the east, just press the menu button before choosing an alignment star and the HC should switch the alignment stars to the other side of the merdian.

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wargrafix
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Re: weird issue... new [Re: rmollise]
      #6322449 - 01/19/14 03:29 PM

Ah no no. Stars to the east are fine. I am unable to use west stars at observation time. If it won't thrown off accuracy then I am happy. :-)

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rmollise
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Re: weird issue... new [Re: wargrafix]
      #6322531 - 01/19/14 04:13 PM

What I am saying, is you can choose the hemisphere of the alignment stars. And, yes, as long as you center the alignment stars properly AND add calibration stars, go-to will be good across the entire sky.

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wargrafix
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Re: weird issue... new [Re: rmollise]
      #6322861 - 01/19/14 07:14 PM

Thank you very much. :-)
The dec cable, any advice on that?


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guyroch
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Re: weird issue... new [Re: wargrafix]
      #6322912 - 01/19/14 07:55 PM Attachment (5 downloads)

Quote:

Thank you very much. :-)
The dec cable, any advice on that?




As long as you plug the DEC cable in the proper place as labeled on the mount it should not matter which end you plug where as far as I know. Just plug one end of the cable into the port on the electronics panel labeled DEC Port and plug the other end of the cable into the port located on the declination motor drive.

The little thing you see at one end of the DEC cable is a Ferrite beads. I have mine plugged in with the Ferrite beads on the electronics panel side. I've seen other setup with the Ferrite beads on the declination motor.

Guylain

Edited by guyroch (01/20/14 07:04 PM)


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wargrafix
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Re: weird issue... new [Re: guyroch]
      #6323191 - 01/19/14 10:38 PM

Ah thank you. Does it matter which where its plugged in? I will try your configuration.

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pfile
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Re: weird issue... new [Re: wargrafix]
      #6323255 - 01/19/14 11:13 PM

i think that's a ferrite bead... it's intended to cut down on radiated emissions from the computer in the mount and/or choke off any external radio sources (or even electrical noise from the dec motor) from being coupled into the mount computer via the dec cable.


http://en.wikipedia.org/wiki/Ferrite_bead

rob


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guyroch
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Re: weird issue... new [Re: pfile]
      #6323287 - 01/19/14 11:29 PM

Quote:

i think that's a ferrite bead... it's intended to cut down on radiated emissions from the computer in the mount and/or choke off any external radio sources (or even electrical noise from the dec motor) from being coupled into the mount computer via the dec cable.


http://en.wikipedia.org/wiki/Ferrite_bead

rob




Yes, you're right. Ground loop isolators are more for removing noise and hum from your home or car stereo, etc.

Ferrite beads are put around cables to help with rejection of RFI and EMI interference.

I have edited my post, thank you.

Guylain


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wargrafix
sage


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Loc: Trinidad
Re: weird issue... new [Re: guyroch]
      #6323314 - 01/19/14 11:47 PM

Ok I am certain this is the best forum ever! I have these at work and no one knows a clue what they are. :-D

I thought since its a straight through cable it wouldn't matter but I guess that the fat end goes on the electronic panel.


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guyroch
Vendor (BackyardEOS)
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Reged: 01/22/08

Loc: Under the clouds!
Re: weird issue... new [Re: wargrafix]
      #6323383 - 01/20/14 12:53 AM

Quote:

Ok I am certain this is the best forum ever!




Ha! Wait until you tell us you have money to spend and you are looking for recommendation... we will gladly gang up on you and spend all your money for you , we are nice that way

Guylain


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wargrafix
sage


Reged: 04/10/13

Loc: Trinidad
Re: weird issue... new [Re: guyroch]
      #6323391 - 01/20/14 01:02 AM

ROFL. isn't that the best part of being here? :-D
In trinidad astro gear is hard to come by. I got my.9.25 from a guy who brings in for the army. I will find things in the most obscure ways. I walk into an old as hell photo shop and walk out with 2 pentax lenses.

I got the cash but the items are tough to come by. I order sparingly since our duty and taxes are the equivalent of a back alley thug with a rusty shank.


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wargrafix
sage


Reged: 04/10/13

Loc: Trinidad
Re: weird issue... new [Re: wargrafix]
      #6325051 - 01/20/14 09:13 PM

So its time to report. Clear skies this evening. Unfortunately work tomorrow but I got stuff done.

So I decided to pick my spot and set up. I am in neither camp of level or no level. I am a student. I decided to raise the appropriate legs to read level on the bubble level of the mount. So far so good.
Night comes and alignment begins. I start with sirius and sure enough it comes close and after lining up I go on to the other stars. Then comes aspa. It gets nice and close.

Assuming you are looking through a diagonaled eye piece 25mm I begin adjusting the alt-az knobs and the lat control. Let me tell you, those things are a pain to use. Now no matter what I do the star of choice rigel moves left or right but it stays in the lower portion of field of view and nothing sends it to the middle whice is up if looking through the eyepiece. I fudged a little and played with the east leg and go it in the middle. I synced and unsynced and went to m42 it was a bit to the left and I had to use hand controls to get it centered. I noticed there was drift.
I used the precise goto and it worked somewhat. Stars trailed in 30 second shots from right to left.


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dragonslayer1
scholastic sledgehammer


Reged: 02/25/12

Loc: SLC, UT
Re: weird issue... new [Re: wargrafix]
      #6325063 - 01/20/14 09:20 PM

Thats good, after your ASPA next time, try a full shutdown of the mount and then another 2+4 then see, Kasey

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wargrafix
sage


Reged: 04/10/13

Loc: Trinidad
Re: weird issue... new [Re: dragonslayer1]
      #6325579 - 01/21/14 06:31 AM

I will certainly try that. I am concerned that while I was able to get it close in the finderscope it was very frustrating to get it in the middle of the eyepiece. fudging with the leg doesn't seem like a good option...unless thats how its done.

The right to left trailing and jupiter not appearing in the middle but on the right of 25mm leaves me a bit concerned.


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wargrafix
sage


Reged: 04/10/13

Loc: Trinidad
Re: weird issue... new [Re: wargrafix]
      #6327705 - 01/22/14 07:09 AM

Last night was another clear and super steady night.

I took out the mount and made sure it was level and the scope balanced. When night fell I ad my manual and picked up the manual and begin alignment again, this time i carefully used the legs to ever so slightly put the object into view. I used the alt az controls when it came to the eyepiece.

Shutdown and did my 2+4 alignment. Sure enough I found every target. Final issue. The objects are still to the right and they slowly drift to the left. Any clues what to do? I am getting there folks!

Also I used tape to mark of the EXACT point where my mount is so when I do it next I will know where to plunk down the mount.


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dragonslayer1
scholastic sledgehammer


Reged: 02/25/12

Loc: SLC, UT
Re: weird issue... new [Re: wargrafix]
      #6327891 - 01/22/14 09:18 AM

go into menu on youy handcontrol and see what it says when you pull up tracking. I don't have a VX but I believe it should say EQ South and Sidereel (you are in the southern hemisphere I believe.. Kasey

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rmollise
Postmaster
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Reged: 07/06/07

Re: weird issue... new [Re: wargrafix]
      #6327941 - 01/22/14 09:46 AM

As far as the objects being on the right, I would not, as I said some posts back on this convoluted thread, expect objects to be dead center. Not always. If they are in the eyepiece, I'd say "good enough."

The drifting? Simple. You need to tighten up your polar alignment. That is what causes drift. It's not clear how you polar aligned from your post. But if you want to minimize the drift you are seeing, do the built in AllStar polar alignment after your go-to alignment. That is assuming you have the tracking setup as the poster above alludes to.

Edited by rmollise (01/22/14 09:47 AM)


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wargrafix
sage


Reged: 04/10/13

Loc: Trinidad
Re: weird issue... new [Re: rmollise]
      #6327976 - 01/22/14 10:10 AM

I am in the north hemisphere. 10 degrees north.

Uncle rod I used the ASPA, that's how I have been finding my targets better. I did my first calibration and used ASPA and got things aligned using positioning and latitude. Its the drift that remains, I have a theory that once I tighten the polar alignment the drift will lessen. I may try again tonight if the weather and schedule permits.
While I know not to expect objects to be dead center always, for AP I will need to get it close as possible.

This has been a convoluted thread, but it seems i am getting there, no?


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guyroch
Vendor (BackyardEOS)
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Reged: 01/22/08

Loc: Under the clouds!
Re: weird issue... new [Re: wargrafix]
      #6328050 - 01/22/14 10:53 AM

Is the drift continuous or just for a small period of time after a slew?

If it's just for a small amount of time before it settles then it is probably backlash.

Guylain.


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wargrafix
sage


Reged: 04/10/13

Loc: Trinidad
Re: weird issue... new [Re: guyroch]
      #6328079 - 01/22/14 11:09 AM

Sadly it will settle on a target and over time, say minutes there will be motion. To better illustrate, it will be on the extreme right when it finds the target and after say 20 mins or so it would have drifted to the extreme left of the eyepiece

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rmollise
Postmaster
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Reged: 07/06/07

Re: weird issue... new [Re: wargrafix]
      #6328089 - 01/22/14 11:11 AM

Quote:

I am in the north hemisphere. 10 degrees north.

Uncle rod I used the ASPA, that's how I have been finding my targets better. I did my first calibration and used ASPA and got things aligned using positioning and latitude. Its the drift that remains, I have a theory that once I tighten the polar alignment the drift will lessen. I may try again tonight if the weather and schedule permits.
While I know not to expect objects to be dead center always, for AP I will need to get it close as possible.

This has been a convoluted thread, but it seems i am getting there, no?




Which direction is the drift? I mean E/W/N/S? if north/south, it is due to polar alignment.


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wargrafix
sage


Reged: 04/10/13

Loc: Trinidad
Re: weird issue... new [Re: rmollise]
      #6328260 - 01/22/14 12:26 PM

its south and drifts north. How do I fix it?

edit: if the orion nebula is right in the eyepiece and drifts to the left, that is south to north

Edited by wargrafix (01/22/14 12:31 PM)


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wargrafix
sage


Reged: 04/10/13

Loc: Trinidad
Re: weird issue... new [Re: wargrafix]
      #6329037 - 01/22/14 06:11 PM

Wanted to take out the mount tonight but clouds!

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wargrafix
sage


Reged: 04/10/13

Loc: Trinidad
Re: weird issue... new [Re: wargrafix]
      #6330467 - 01/23/14 11:56 AM

I was wondering whey celestron used those stickers to indicated mount home position rather than metal punches or emboss so that there would be no chance of the default position being lost.

Tonight i hope to do drift alignment


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rmollise
Postmaster
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Reged: 07/06/07

Re: weird issue... new [Re: wargrafix]
      #6330535 - 01/23/14 12:18 PM

The VX uses engraved marks rather than stickers...

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wargrafix
sage


Reged: 04/10/13

Loc: Trinidad
Re: weird issue... new [Re: rmollise]
      #6330604 - 01/23/14 12:48 PM

ah! I have seen the mount but I heard that it did. If I were to go over to celestron I would tell them," Oye, stamp arrows in all your mounts, put dew shields as part of the basic ota package and while you are at it, fire the people who made the alt az knobs....try fine tuning the mount with those for a while, lets see your fingers after that, Celestron execs!"

I like Celestron but I am not above tell them when they are foolish.I will pat them on the head though...the Advanced GT is a nice system to work with.


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wargrafix
sage


Reged: 04/10/13

Loc: Trinidad
Re: weird issue... new [Re: wargrafix]
      #6331935 - 01/24/14 04:57 AM

Ok. So last night I set out to solve the drift issue. Set up the mount within the triangle. Sighted my stars and made sure I got my calib stars and did aspa. Mount was level and everything. My goto still sent my targets either lower right or to the bottom. In thr case of m67, piece of the cluster is outside of the 25mm.
Those if you who so ap, is this common? Also do you just use the direction buttons to center it?

The drift was notably less. I moved the head in alt az a little. I hope this lessens the drift. The drift is south to north.


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rmollise
Postmaster
*****

Reged: 07/06/07

Re: weird issue... new [Re: wargrafix]
      #6332125 - 01/24/14 08:51 AM

Quote:

ah! I have seen the mount but I heard that it did. If I were to go over to celestron I would tell them," Oye, stamp arrows in all your mounts, put dew shields as part of the basic ota package and while you are at it, fire the people who made the alt az knobs....try fine tuning the mount with those for a while, lets see your fingers after that, Celestron execs!"

I like Celestron but I am not above tell them when they are foolish.I will pat them on the head though...the Advanced GT is a nice system to work with.




The altitude and azimuth knobs on the VX have also been improved significantly.


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rmollise
Postmaster
*****

Reged: 07/06/07

Re: weird issue... new [Re: wargrafix]
      #6332127 - 01/24/14 08:52 AM

Quote:

Ok. So last night I set out to solve the drift issue. Set up the mount within the triangle. Sighted my stars and made sure I got my calib stars and did aspa. Mount was level and everything. My goto still sent my targets either lower right or to the bottom. In thr case of m67, piece of the cluster is outside of the 25mm.
Those if you who so ap, is this common? Also do you just use the direction buttons to center it?

The drift was notably less. I moved the head in alt az a little. I hope this lessens the drift. The drift is south to north.




Sounds normal to me.


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wargrafix
sage


Reged: 04/10/13

Loc: Trinidad
Re: weird issue... new [Re: rmollise]
      #6332244 - 01/24/14 10:03 AM

ah ok, thank you. For AP proposes, moving the image to he center after goto had found it should keep it in view? I am asking this in the assumption i have done rough drift alignment.

The VX looks good, but I can't really afford another mount right now.


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dragonslayer1
scholastic sledgehammer


Reged: 02/25/12

Loc: SLC, UT
Re: weird issue... new [Re: wargrafix]
      #6332315 - 01/24/14 10:55 AM

after you center your target try sync to it and see what happens, Kasey

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rmollise
Postmaster
*****

Reged: 07/06/07

Re: weird issue... new [Re: dragonslayer1]
      #6332360 - 01/24/14 11:15 AM

Sync is really not the way to go. It might improve pointing in the area you are in, but it will THROW OFF pointing in other areas of the sky. If the mount is putting objects in the eyepiece, most of us would say "good enough."

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rmollise
Postmaster
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Reged: 07/06/07

Re: weird issue... new [Re: wargrafix]
      #6332364 - 01/24/14 11:17 AM

Quote:

ah ok, thank you. For AP proposes, moving the image to he center after goto had found it should keep it in view? I am asking this in the assumption i have done rough drift alignment.

The VX looks good, but I can't really afford another mount right now.




I'm not sure I understand your question. Yes, if you've done a halfway decent polar alignment, the object will stay in the eyepiece.


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wargrafix
sage


Reged: 04/10/13

Loc: Trinidad
Re: weird issue... new [Re: rmollise]
      #6332482 - 01/24/14 12:12 PM

I have seen when syncing a particular object might put other objects in the finder but nowhere in an eyepiece.

I will try to rephrase; If the object is showing up in the edge of say a 25mm eyepiece and I use the hand controller to move it to the center of the view, will it still track?

Edited by wargrafix (01/24/14 12:45 PM)


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schluterdude
super member


Reged: 08/05/13

Loc: Centerville, OH
Re: weird issue... new [Re: wargrafix]
      #6332755 - 01/24/14 02:08 PM

If you align your goto first, then ASPA, yes, pointing accuracy will change until you set up the GOTO again. You've mechanically moved the mount... Instead of using synch as a cheater (that's really meant for if you need to move the tube, like spinning a newt), use the "replace" function.

Pick an object, then go into the alignment menus. Somewhere in there is a list of objects you used originally. Select one of them and press enter, then choose replace. I can't remember exactly where the menu is, and I don't have my manual with me. I'll look it up later.

Or, power down, power up, and run the full goto setup again! Everything will come up dead nuts!


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wargrafix
sage


Reged: 04/10/13

Loc: Trinidad
Re: weird issue... new [Re: schluterdude]
      #6332853 - 01/24/14 02:37 PM

Thanks! I will try that tonight!

Normally I will do 2 stars (Sirius + Betelgeuse) then maybe Canopus and castor.

Then I go to ASPA and it slews to castor and i do the alt az changes, then sync...the unsync. Power down, put indexes correct begin the alignment process again. I have not tried the replace since I would have used the last calib star for ASPA.

What did I do wrong?


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John608
journeyman


Reged: 03/24/12

Loc: California
Re: weird issue... new [Re: wargrafix]
      #6334032 - 01/25/14 01:46 AM

Tracking is controlled by Polar Alignment accuracy. You could manually slew to any star then center it in the eyepiece and the mount will track it if you have polar aligned properly and you have set tracking properly. An accurate goto alignment is necessary for an accurate ASPA polar alignment. Perfectly accurate? No, the ASGT and the ASGT are not perfectly accurate mechanical devices, and their inaccuracies will be reflected in not quite perfect gotos and polar alignment. But both mounts are capable of more than enough accuracy for visual use and for some astrophotography.

If you're getting objects within the field, not centered but within the field of a 25mm eyepiece, that's pretty good. Sometimes you may get it a little better, but that's good and useable. Center the object with the hand controller, make sure tracking is set up properly and you are good to go. I have had objects remain in the field of view of a medium power eyepiece for hours with an ASPA polar alignment with my ASGT. Just don't expect everything to be perfect, it won't be! But it'll be useable and a heck of a lot better than the old days with just a clock drive on the RA axis and setting circles.

Good Luck!

John G


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wargrafix
sage


Reged: 04/10/13

Loc: Trinidad
Re: weird issue... new [Re: John608]
      #6337043 - 01/26/14 04:32 PM

Well I can report a great level of success.
Goto has improved but I am sure I can get it better.
Tracking is significantly better. Stars look a little cometish. De focused a little to a corner of the star. I used the handset to centre the objects but photos show trailing.


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schluterdude
super member


Reged: 08/05/13

Loc: Centerville, OH
Re: weird issue... new [Re: wargrafix]
      #6337111 - 01/26/14 04:57 PM

Visually you should not notice trailing, only in images. If the stars look funny visually, something is goofy in the optic train.

The only way to get super accurate with setup is using an illuminated reticle, or software that will overlay crosshairs for you like backyard EOS.

Or, use a super high power eyepiece with a very narrow field of view...


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schluterdude
super member


Reged: 08/05/13

Loc: Centerville, OH
Re: weird issue... new [Re: schluterdude]
      #6337116 - 01/26/14 05:00 PM

Oops, never mind that first comment on trailing :-P

Have you considered an off axis guider? Cheaper than a tracking scope setup, just means you have to stay at the scope. Use the motor speed function to slow movements down, and use the HC to correct positioning. Same thing though, you'll need the illuminated reticule.


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wargrafix
sage


Reged: 04/10/13

Loc: Trinidad
Re: weird issue... new [Re: schluterdude]
      #6338191 - 01/27/14 07:37 AM

Hi all. I considered an off axis guider but right now its a little pricey. Thinking of saving for a illuminated reticule.

I will give a bit more detail on the night's work. I leveled the mount and balanced the scope. Did the alignment and ASPA and shut down. I redid everything and go hings found but that the targets were still on the edge. I tried another round of alignment and got it a bit better.

I used the Eskimo nebula as my drift test and found there was south north drift. I adjusted attitude and 30 second exposures were better. The stars have an offset coma though. Not sure why.

I


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wargrafix
sage


Reged: 04/10/13

Loc: Trinidad
Re: weird issue... new [Re: wargrafix]
      #6347075 - 01/31/14 11:58 AM

I am going to the in-laws today. Scope in tow!:-)

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wargrafix
sage


Reged: 04/10/13

Loc: Trinidad
Re: weird issue... new [Re: wargrafix]
      #6357097 - 02/05/14 07:36 AM

In spite of the clouds i got one night of good weather. Setup was challenging because of the humidity and cold. I realized that leveling the mount make no difference in ASPA. I setup there and even though it was not balanced in the bubble level, targets showed up in the dead center of my 25mm eyepiece every time!:-)

Photos were good, but a target lower in the south there was field rotation. Any advice?


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