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Equipment Discussions >> Mounts

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will1384
member


Reged: 02/22/13

Can't get properly aligned with VX mount
      #5809950 - 04/20/13 01:43 AM

I am having trouble getting my VX mount properly aligned, I am unable to even take a 30 second exposure without getting star trails, this is what I am doing.


(1) I move the tripod so that the Azimuth peg is pointing to North, I use a Map Compass.

(2) I use a bubble level on top of the tripod, to level the tripod.

(3) I place the mount on the tripod, and set my latitude.

(4) Put the Telescope on the mount, install the weight, install the telescope, and balance the telescope in both RA and DEC.

(5) I turn the mount on, and enter my GPS, date, and time.

(6) I do the two star aliment, add one or two calibration stars, as my view of the sky is very limited.

(7) I select and go to a star with the hand control.

(8) I then press the Align button, then select Polar Align, then select Align Mount, and follow the directions.

(7) I then turn off the mount, and return the mount to the default RA and DEC marks.

(8) I then turn it back on, do the two star aliment, add one or two calibration stars, then start taking pictures.

A few notes:

(1) I am using a 12.5mm Reticle Eyepiece
(2) I use a Telrad Finder
(3) My telescope is a Sky-Watcher Pro 80ED, Aperture 80mm, Focal Length 600mm,Focal Ratio 7.5.
(4) Camera is a Panasonic G3, Micro Four Thirds Sensor, with prime focus adapter.
(5) I use the camera's 10 Self-timer to trip the shutter.

What am I doing wrong ?


I have a Netbook, Bluetooth GPS dongle, guide scope with a somewhat sensitive camera, and the cables I need, but I would like to know what I am doing wrong before I try using the Netbook to control the VX mount.


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cn register 5
scholastic sledgehammer


Reged: 12/26/12

Re: Can't get properly aligned with VX mount new [Re: will1384]
      #5810054 - 04/20/13 04:08 AM

There are two possibilities:
The polar align isn't good.
Periodic error.

If you do a new alignment after the polar align you can check the align error. A good ASPA should end up with an error of 10 arc minutes or less. Also gotos should be accurate, with that scope and EP I'd expect objects to end up fairly close to the centre of the EP. Periodic error will produce a more or less constant drift that's more in the Dec direction than the Ra direction.

The uncorrected periodic error on my AVX is about 33 arc sec peak to peak. Is that enough to give the trailing you are seeing? If this is the case the trailing will be in the Ra direction and eventually should reverse in direction. it's possible to reduce this by recording the error and applying this PEC.

I've always used guiding.

BTW nice report, it helps a lot with giving good feedback.

Chris


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Cliff Hipsher
Pooh-Bah
***

Reged: 12/31/08

Loc: North Chesterfield, VA
Re: Can't get properly aligned with VX mount new [Re: will1384]
      #5810222 - 04/20/13 08:13 AM

Quote:

I am having trouble getting my VX mount properly aligned, I am unable to even take a 30 second exposure without getting star trails, this is what I am doing.


(1) I move the tripod so that the Azimuth peg is pointing to North, I use a Map Compass. You need to compensate for local magnetic declination. http://www.ngdc.noaa.gov/geomag-web/#declination

(2) I use a bubble level on top of the tripod, to level the tripod. Some will say there is no need to level. I'm not one of them. Level the mount AFTER you have everything assembled.

(3) I place the mount on the tripod, and set my latitude.

(4) Put the Telescope on the mount, install the weight, install the telescope, and balance the telescope in both RA and DEC.

(5) I turn the mount on, and enter my GPS, date, and time.

(6) I do the two star aliment, add one or two calibration stars, as my view of the sky is very limited.

(7) I select and go to a star with the hand control.

(8) I then press the Align button, then select Polar Align, then select Align Mount, and follow the directions.

(7) I then turn off the mount, and return the mount to the default RA and DEC marks.

(8) I then turn it back on, do the two star aliment, add one or two calibration stars, then start taking pictures.

A few notes:

(1) I am using a 12.5mm Reticle Eyepiece
(2) I use a Telrad Finder
(3) My telescope is a Sky-Watcher Pro 80ED, Aperture 80mm, Focal Length 600mm,Focal Ratio 7.5.
(4) Camera is a Panasonic G3, Micro Four Thirds Sensor, with prime focus adapter.
(5) I use the camera's 10 Self-timer to trip the shutter.

What am I doing wrong ? If your hand controller is not prompting you to make mechanical adjustments in ALT and AZ, then you are not doing a Polar Alignment. The purpose of a Polar Alignment is to align the RA axis to the North Celestial Pole. The most accurate method is called a Declination Drift Alignment

With that being said, your biggest mistake is putting the cart before the horse. Learning the ins and outs of being successful at imaging is not like baking a cake or assembling a kit of parts. You need to start slowly and methodically, taking things one step at a time, and to do that you need to forget about cameras and focus on learning how the mount works, how the software works, how to do a proper polar alignment, and so on. When you get to the point where you can set up, get aligned, and consistently GoTo and then accurately track an object, THEN you can start thinking about imaging.


I have a Netbook, Bluetooth GPS dongle, guide scope with a somewhat sensitive camera, and the cables I need, but I would like to know what I am doing wrong before I try using the Netbook to control the VX mount.




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pjensen
super member


Reged: 04/08/12

Loc: Highland Village, Tx
Re: Can't get properly aligned with VX mount new [Re: will1384]
      #5810307 - 04/20/13 08:45 AM

Quote:


(6) I do the two star aliment, add one or two calibration stars, as my view of the sky is very limited.




My GoTo's were not accurate until I did the 2 alignment stars plus four calibration stars. When you do 4 calibration stars, the pointing model gets updated on the mount. You might try a factory reset to clean out the old values. When the mount is presenting a calibration star, you can press the scroll down key and find a star that you can see. You will need a star chart as there are dozens (of lesser known stars). You can press the menu key and it will toggle between W, E and blank (West, East and all) - this limits the stars presented.

Also be aware that each time you put the OTA on the mount, it needs to be at the exact same location on the saddle. Apparently the mount carries over some values from your prior setup - unless you do a reset.

Don't know if you can see polaris - but if you can, use a polar scope. It is so ridiculously simple and quick to do. On mine, it takes 90 seconds or less. I can not imagine why anyone would skip this as it is a great starting point (to mechanically align the mount - which needs to be done anyway).

My guess is the mount (software) requires the same mechanical setup each time (OTA position on the mount saddle, tripod aligned with the NCP, accurate time to a few seconds). If any of this varies, then the GoTo accuracy suffers.

Note I am using a CG5AT mount and I am assuming your handset uses the same software.






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MartinTreadgold
super member


Reged: 04/17/13

Loc: Netherlands
Re: Can't get properly aligned with VX mount new [Re: pjensen]
      #5810510 - 04/20/13 10:13 AM

Things to check:-

Did you....

1) Connect the DEC port cable correctly?
2) is your 12V power supply fully charged? for example I lost alignment when the power was about to run out..
3) Secure the DEC and RA Locks?
4) Are the GPS co-ords correct?
5) enter all the calibration (calib) stars, and is the mount alignment successful?
6) read the manual?? could be something you missed..

I think this is probably something very simple.

You could try reflashing the firmware via the R232 cable, and/or factory reset the hand controller.

I just got my VX mount 3 weeks ago, and it took a while for me to understand how to use it properly. Just takes a bit of getting used to...

I'll be happy to answer more questions and compare notes with you


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Whichwayisnorth
Pooh-Bah
*****

Reged: 07/04/11

Loc: Southern California
Re: Can't get properly aligned with VX mount new [Re: MartinTreadgold]
      #5810758 - 04/20/13 12:13 PM

The only issue I have with what you are doing is that you are not doing the full 4 calibration before doing the all star polar alignment. It is very important that you do the full 2+4 before you do an ASPA as the ASPA needs to have that full calibration to be accurate.

Also as was mentioned already, you didn't say if you made the manual physical adjustments to your mount when it asked you to. Please verify that you are not using the hand controller to center the star during ASPA but are instead cranking on the knobs to center it.

2+4 then ASPA should get you very close. I've had 17 minutes of no drift after doing that.

Also one last thing which was already mentioned as well. Double check that your clutches are all the way tight.

I realize you have limited stars to choose from. If you don't have enough to do a 2+4 then you will need to use a polar scope to get it as close as you can.

Edited by Whichwayisnorth (04/20/13 12:24 PM)


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will1384
member


Reged: 02/22/13

Re: Can't get properly aligned with VX mount new [Re: will1384]
      #5810942 - 04/20/13 01:39 PM

I have read threw the replies, there are a few things I need to bring up.


I can not see Polaris as trees block its view, and I can not see any more alignment stars as trees also block them.

The GPS is correct, as is the time, I am using my phone to get GPS and time, and no its not WIFI or AGPS, my phone has a real GPS chip inside.

I use a 12V 7Ah sealed lead acid battery that I charge after every use.

The magnetic declination were I live is 1-1/2+ degree.

The hand controller "is" prompting me to adjust the ALT and AZ controls on the mount during the Polar Align/Align Mount routine.

So what do I try next?


Here are the stars that I use, as I only have a narrow view to the west.

Capella
Procyon
Pollux
Castor
Betelgeuse - if I can see it
Regulus - if I can see it
Algieba - if I can see it

And a lot of times the hand controller tries to limit me to stars I cant see, and wont let me select the few I can.

I can cut down a few trees in my yard, but I can't cut the neighbors trees down, and the few trees in my yard that I can cut down wont help much.


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Whichwayisnorth
Pooh-Bah
*****

Reged: 07/04/11

Loc: Southern California
Re: Can't get properly aligned with VX mount new [Re: will1384]
      #5810976 - 04/20/13 02:01 PM

Then you'll have to go back to basics and manual drift align.

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pjensen
super member


Reged: 04/08/12

Loc: Highland Village, Tx
Re: Can't get properly aligned with VX mount new [Re: will1384]
      #5811359 - 04/20/13 04:41 PM

Quote:


So what do I try next?





If it were me, I would try it in a better location - just verify that it could work correctly.

The visible stars you list are pretty close together. Add in that you can't see Polaris and you are done.

Looks like all you can do is the drift alignment - which takes a lot of time. Sorry.

By the way, have you done a reset?


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zawijava
scholastic sledgehammer
*****

Reged: 10/06/07

Loc: Wells, Maine 04090
Re: Can't get properly aligned with VX mount new [Re: will1384]
      #5811437 - 04/20/13 05:39 PM

Are you "unsyncing" from the star you are using for ASPA? After the ASPA is complete you should "unsync" that star before proceeding. -Tim

Quote:

I have read threw the replies, there are a few things I need to bring up.


I can not see Polaris as trees block its view, and I can not see any more alignment stars as trees also block them.

The GPS is correct, as is the time, I am using my phone to get GPS and time, and no its not WIFI or AGPS, my phone has a real GPS chip inside.

I use a 12V 7Ah sealed lead acid battery that I charge after every use.

The magnetic declination were I live is 1-1/2+ degree.

The hand controller "is" prompting me to adjust the ALT and AZ controls on the mount during the Polar Align/Align Mount routine.

So what do I try next?


Here are the stars that I use, as I only have a narrow view to the west.

Capella
Procyon
Pollux
Castor
Betelgeuse - if I can see it
Regulus - if I can see it
Algieba - if I can see it

And a lot of times the hand controller tries to limit me to stars I cant see, and wont let me select the few I can.

I can cut down a few trees in my yard, but I can't cut the neighbors trees down, and the few trees in my yard that I can cut down wont help much.




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Stew57
Carpal Tunnel
*****

Reged: 05/03/09

Loc: Silsbee Texas
Re: Can't get properly aligned with VX mount new [Re: zawijava]
      #5811485 - 04/20/13 06:17 PM

The 4 in a 2 + 4 alignment is an average of the 4 calibration stars according to Celestron. They compensate for nonorthogonality and some flexure.

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will1384
member


Reged: 02/22/13

Re: Can't get properly aligned with VX mount new [Re: zawijava]
      #5811674 - 04/20/13 08:10 PM

Quote:

Are you "unsyncing" from the star you are using for ASPA? After the ASPA is complete you should "unsync" that star before proceeding. -Tim




Nope, that's what I have been missing , OK, I will try that next, one thing that worries me is that the mount never gets the stars in or near the center of the eyepiece, I can see the stars in the 12.5mm Reticle Eyepiece after the two star aliment with one or two calibration stars, but even after the Polar Align / Align Mount the stars are always about halfway to the outer edge of the eyepiece, never near the center.

If that still does not work I may try Alignmaster on my netbook.

Thanks!


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will1384
member


Reged: 02/22/13

Re: Can't get properly aligned with VX mount new [Re: will1384]
      #5814462 - 04/22/13 12:24 AM

This is what I did:

(1) Move the tripod so that the Azimuth peg is pointing to North, use a real Compass.

(2) Use a bubble level on top of the tripod, to level the tripod.

(3) Place the mount on the tripod, and set your latitude.

(4) Put the Telescope on the mount, install the weight, install the telescope and
balance the telescope in both RA and DEC.

(5) Turn the mount on, and enter your GPS, date, and time.

(6) Do the two star aliment, add as may calibration stars as you can, up to four.

-- I added two calibration stars this time --

(7) Get out of the aliment menu, and select and go to a star with the Hand Control.

(8) Press the Align button, then select Polar Align, then select Align Mount, and follow the directions.

(9) Undo the "Sync" that was done in step (8), by pressing the Align button and then select Undo Sync, and press Enter.

(10) Go to a star with the Hand Control, Press the Align button, and select Alignment Stars, replace each star.

-- I also replaced the two calibration stars --

And it did better, but even at a 30 second exposure I am still getting a small amount of star trails when I zoom the image to 1:1.

I was getting to cold so I skipped trying alignmaster.

Another thing I noticed is a lot of slop or looseness in the Latitude Adjustment.

Anything else to try?


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cn register 5
scholastic sledgehammer


Reged: 12/26/12

Re: Can't get properly aligned with VX mount new [Re: will1384]
      #5814614 - 04/22/13 03:52 AM

How much, in arc seconds, is a small amount of drift in 30 seconds?

And in what direction is it relative to the Ra and Dec axes?

It could be periodic error, in which case it will be in the Ra direction, or it could be polar align error, in which case it will tend to be more in the dec direction. More likely it's a combination of both.

But without some information about what a small amount is no one can say.

Chris


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Jeff2011
Pooh-Bah
*****

Reged: 01/01/13

Loc: Sugar Land, TX
Re: Can't get properly aligned with VX mount new [Re: cn register 5]
      #5816337 - 04/22/13 08:48 PM

Will,

Have you tried this:
http://www.cloudynights.com/item.php?item_id=2838


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will1384
member


Reged: 02/22/13

Re: Can't get properly aligned with VX mount new [Re: cn register 5]
      #5816589 - 04/22/13 11:48 PM

Quote:

How much, in arc seconds, is a small amount of drift in 30 seconds?

And in what direction is it relative to the Ra and Dec axes?

It could be periodic error, in which case it will be in the Ra direction, or it could be polar align error, in which case it will tend to be more in the dec direction. More likely it's a combination of both.

But without some information about what a small amount is no one can say.

Chris




The amount of star trail looked to be 2 stars in length, for a 30 second exposure, and it looked like some brighter stars had a comet like appearance with the tail in the same direction as the star trails.


Using two images taken one after the other, one star drifted from 2773,286 to 2773,292, in 100 seconds, image size is 4592x3448, star size was 35 pixels.

And in another set of images, the same star drifted from 2860,681 to 2818,575 in 125 seconds, image size is 4592x3448, star size was 35 pixels.

The trails seem to change as I take images, and then give few somewhat good images, then back to slowly changing directions like this :

(1) Very small trail pointing to the top right.
(2) Larger trails pointing to the top.
(3) Almost perfect, very small trail pointing to the right.
(4) Almost perfect, very small trail pointing to the right.
(5) Almost perfect, very small trail pointing to the right.
(6) Almost perfect, very small trail pointing to the right.
(7) Almost perfect, very small trail pointing to the right.
(8) Larger trails pointing to the left
(9) Almost perfect, very small trail pointing to the right.
(10) Very small trail pointing to the bottom right.
(11) Very small trails pointing to the top.
(12) Very small trails pointing to the top.


The Panasonic G3 pixel size is 3.75 microns, and the focal length of the Telescope is 600mm, so I divide 3.75 by 600 and get 0.00625, then multiply by 206.3 to get 1.289375, is that correct ?


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will1384
member


Reged: 02/22/13

Re: Can't get properly aligned with VX mount new [Re: Jeff2011]
      #5816627 - 04/23/13 12:12 AM

Not yet, but I have been thinking about something like that, problem is that my adjustment knobs seem over sensitive, just the slightest turn of the larger Latitude Adjustment knob moves the star halfway across eyepiece, and when I try to set the smaller Latitude Adjustment knob it it just becomes a fight between larger and smaller Latitude Adjustment knobs,

I am going to try Alignmaster first, then move the scope to were I can see Polaris, as I found a small little hole in the tree cover that I can see Polaris, and I have a polar scope on order, problem is, the area has an even more limited view of the sky.

I get it figured out someday LOL


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Cliff Hipsher
Pooh-Bah
***

Reged: 12/31/08

Loc: North Chesterfield, VA
Re: Can't get properly aligned with VX mount new [Re: will1384]
      #5817029 - 04/23/13 09:02 AM

Quote:

Not yet, but I have been thinking about something like that, problem is that my adjustment knobs seem over sensitive, just the slightest turn of the larger Latitude Adjustment knob moves the star halfway across eyepiece, and when I try to set the smaller Latitude Adjustment knob it it just becomes a fight between larger and smaller Latitude Adjustment knobs,

I am going to try Alignmaster first, then move the scope to were I can see Polaris, as I found a small little hole in the tree cover that I can see Polaris, and I have a polar scope on order, problem is, the area has an even more limited view of the sky.

I get it figured out someday LOL




The answer is real simple: Find a different place to do your observing.

I know it a PITA, but at this point you are sweeping against the tide. Your current location is not conducive to being successful, and to be brutally honest, trying to get your gear setup and actually use it where you are is a waste of your time.


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Jeff2011
Pooh-Bah
*****

Reged: 01/01/13

Loc: Sugar Land, TX
Re: Can't get properly aligned with VX mount new [Re: will1384]
      #5817078 - 04/23/13 09:49 AM

Quote:

problem is that my adjustment knobs seem over sensitive, just the slightest turn of the larger Latitude Adjustment knob moves the star halfway across eyepiece, and when I try to set the smaller Latitude Adjustment knob it it just becomes a fight between larger and smaller Latitude Adjustment knobs




I don't have that problem with my mount. I just loosen the knob on the front and adjust with the big knob on the back. And then slightly tighten the knob on the front when done. Regardless of whether you do a star drift or an ASPA, you will need to adjust these knobs.

I found the DSLR star drift to be fairly straight forward. The key is in finding the stars to do the drift on. I use sky safari to locate a star in the south near the intersection of the meridian and the celestial equator. Then I find a star in the east as low as possible and on the celestial equator. Sky Safari has grid lines that I can turn on to make finding these stars easy.

At 430mm focal length, I have been able to get up to 2 minutes without trailing. I recently took 9 shots of the leo triplet at 1.5 min but only 4 had round stars. That is only a 44% success rate. As another CN member pointed out to me, this is a low end mount, so you can't expect unguided shots to be repeatable.

Good luck in getting your mount going. I think you should be able to get some shots at 30 seconds without trailing.


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will1384
member


Reged: 02/22/13

Re: Can't get properly aligned with VX mount new [Re: Cliff Hipsher]
      #5817507 - 04/23/13 01:35 PM

Quote:


The answer is real simple: Find a different place to do your observing.

I know it a PITA, but at this point you are sweeping against the tide. Your current location is not conducive to being successful, and to be brutally honest, trying to get your gear setup and actually use it where you are is a waste of your time.




Were I live there is no were else to setup my telescope, none of my neighbours know me, nor do they have a yard with a good view, trees everywhere, there is one park about 30 minute drive away, but it closes at night, and another park that is farther away, that does stay open all night, but I am likely to get my stuff stolen, I just have to tough if out and use what I have.

BTW I live out in the woods about 30 mile drive from the nearest city.

Later on I plan to build a workshop out of steel cargo containers, and I think I will just stack them to get the height and view I need for the telescope, the cargo containers are 8 foot tall, and different lengths, I am thinking about getting five of them, four of them would be the larger 20 or 40 foot long ones, and the fifth would be a small one sitting on top, the way I need to stack them for stability it would give me 24 foot in hight, and if remove a few problem trees and put the structure in the right spot it would give me a good view of the sky with a small observatory on top of the small cargo container, I was going to build a workshop anyway, just in a different place.

Another idea was using using a larger metal building for a workshop, and having the the construction company add a well supported 16 foot square platform on the roof, but that might cost more than the steel cargo containers.

The problem with this plan is that I need to save up money to build the workshop, and that could take a few years, I still want to find a way to use my telescope in that time.


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