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Equipment Discussions >> Mounts

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roamer
sage
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Reged: 03/21/10

Loc: Michigan
The little leveling bubble on an Atlas EQ-G mount.
      #4512309 - 04/11/11 10:51 PM

Does leveling the mount via that little bubble really matter if you have a good polar alignment?

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jrcrillyAdministrator
Refractor wienie no more
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Reged: 04/30/03

Loc: NE Ohio
Re: The little leveling bubble on an Atlas EQ-G mount. new [Re: roamer]
      #4512348 - 04/11/11 11:10 PM

Once you are polar aligned, a level base is irrelevant. The bubble level can aid in the process of polar alignment by letting you begin with the same elevation you used previously, or to ensure that the AZ and elevation axes don't interact much when you adjust them.

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Bachus
Carpal Tunnel
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Reged: 11/25/05

Loc: Nashville,TN.
Re: The little leveling bubble on an Atlas EQ-G mount. new [Re: jrcrilly]
      #4512418 - 04/11/11 11:47 PM

I don't use it...it's too small to see and read clearly. For me it's just a habit of leveling the tripod. It's not like an extra 1/2 hour to do. A simple Torpedo Level is much easier for me. I level the two rear legs and the the front one. It's 5-6 minutes work.

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jmiele
Patron Saint?
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Reged: 12/04/10

Re: The little leveling bubble on an Atlas EQ-G mount. new [Re: Bachus]
      #4512425 - 04/11/11 11:55 PM

I use it but only as John stated. It's an aid to speed my initial setup. I carry a stack of 1/8" 2"x2" aluminum angles. I can stack them to level quickley on any semi-level surface. Gets me close right out of the gate. Then a couple tweaks while looking through the polar scope and I'm within 2 arc minutes, better sometimes. If imaging I drift align, if not, I'm go to go. Joe

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EricRemy
member
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Reged: 09/24/08

Loc: Quebec, Canada
Re: The little leveling bubble on an Atlas EQ-G mount. new [Re: Bachus]
      #4512517 - 04/12/11 12:50 AM

The one I had on mine was not accurate. I second the torpedo level idea.

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rmollise
Postmaster
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Reged: 07/06/07

Re: The little leveling bubble on an Atlas EQ-G mount. new [Re: roamer]
      #4512730 - 04/12/11 05:54 AM

Quote:

Does leveling the mount via that little bubble really matter if you have a good polar alignment?




No. It doesn't matter before, either. Levelling can help with polar alignment--a little--but certainly isn't needed.


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roamer
sage
*****

Reged: 03/21/10

Loc: Michigan
Re: The little leveling bubble on an Atlas EQ-G mount. new [Re: rmollise]
      #4514499 - 04/12/11 11:36 PM

Thanks, I was curious folks. I had heard somewhere it wasn't, but wanted to verify with you all.

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Doug76
Long Achro Junkie
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Reged: 12/05/07

Loc: Refractor Heaven
Re: The little leveling bubble on an Atlas EQ-G mount. new [Re: roamer]
      #4515257 - 04/13/11 11:09 AM

Since mine went right onto a pier in the observatory, I took the time to level it. My bubble level happened to be accurate, but I did use a carpenters level to do the job.
But I only level by eye my portable CG-5, and it works just fine that way.


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alpal
Post Laureate


Reged: 06/15/09

Loc: Melbourne Australia.
Re: The little leveling bubble on an Atlas EQ-G mount. new [Re: Doug76]
      #4516755 - 04/13/11 11:09 PM

This is all quite strange to me.

I always level my mount with a carpenter's level
as the bubble is wrong (on my EQ6).
I just assumed it was necessary to get accurate alignment
& make the GOTO work.


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roamer
sage
*****

Reged: 03/21/10

Loc: Michigan
Re: The little leveling bubble on an Atlas EQ-G mount. new [Re: rmollise]
      #4516757 - 04/13/11 11:10 PM

Quote:

Quote:

Does leveling the mount via that little bubble really matter if you have a good polar alignment?




No. It doesn't matter before, either. Levelling can help with polar alignment--a little--but certainly isn't needed.




BTW, I like your article in April S & T, Rod. I used it tonite for a lttle bit of variety in my viewing! Much thx.


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Skylook123
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Reged: 04/30/05

Loc: Tucson, AZ
Re: The little leveling bubble on an Atlas EQ-G mount. new [Re: roamer]
      #4517443 - 04/14/11 10:25 AM

Last I checked I have about 350 setups over the last six years with my Atlas, rarely at the same spot since it's used for public outreach around the state of Arizona, and I'll be a contrarian here about leveling. Leveling the tripod with a bulls-eye level, then adding the mount head, makes the process go much faster, much less frustrating chasing polar and stellar alignment. After leveling the tripod, I check the bubble level on the mount head and it seems to agree with the tripod level.

Don't get me started on the goofy latitude scale; mine's about 5 degrees off. If I am setting up at a site that's more than about 20 miles in latitude away from the previous setup spot, I use an inclinometer on the top plate to get a good starting point. The bubble level on my mount head seems to be pretty good, but I still use the bulls-eye level on the tripod since it's easier to adjust the legs without the weight of the mount head installed.


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Dmitri F
sage


Reged: 04/05/05

Loc: New Jersey
Re: The little leveling bubble on an Atlas EQ-G mount. new [Re: Skylook123]
      #4517726 - 04/14/11 12:46 PM

Changing the tripod leveling in the North-South direction has the same effect as adjusting the altitude of the head with the altitude bolts. When polar aligning, I usually do just that by putting or removing some thin plywood sheets under the northern tripod leg. I leave the altitude bolts alone for the reasons obvious to anyone who owns an Atlas - my telescope is usually already loaded on the mount when I polar align, and moving the bolts on the loaded mount is not fun.

Also, I level the tripod with plywood sheets and do't adjust the legs. In my experience, the aluminum tubes are thin and can be very easily dented by overtightening the adjustment bolts so I don't like touching them either.


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M13 Observer
scholastic sledgehammer


Reged: 12/09/06

Re: The little leveling bubble on an Atlas EQ-G mount. new [Re: roamer]
      #4517777 - 04/14/11 01:09 PM

Quote:

Does leveling the mount via that little bubble really matter if you have a good polar alignment?




If you already have a good polar alignment, why are you futzing with the leveling? It won't matter at all.

To get that proper polar alignment you just might want to level that mount so that corrections to one axis don't interact with the other axis, but this is all dependent on exactly what you are doing.

For observing with short focal length instruments polar alignment can be many degrees off and most everything will still work pretty closely so just plunk it down, eyeball the RA axis to Polaris and start using the telescope. I do this solar observing and imaging. I just eyeball align the mount to where I think polar north is and start to use the scope. Yes, Sol will drift up or down a bit, depending if I am pointing too far east or west of true north as time passes, but I can spend quite some time imaging or viewing before I have to hand correct the pointing. Same goes for at night for observing. I can spend quite some time on the moon or a planet before it drifts out of the field of view. For longer focal length instruments, one might want to take a bit more care and roughly align by looking through the polar axis and centering Polaris or quickly with a polar alignment scope if available.

For imaging with short focal length optics and short exposures, a super accurate polar alignment just isn't necessary. The prior method of sighting through the polar axis or using a polar alignment scope to roughly polar align will be enough. As soon as you start extending the focal length, or go to longer exposures, or both, this all changes. Very quickly, more rigorous polar alignment techniques will be required and leveling the mount will help to keep the frustration factor down. The reason for this is the interaction of one axis with the other when polar aligning with a non-level mount. If the mount is perfectly level, then a change to the azimuth will be just that, a change to the azimuth, and a change to the inclination will be the same, just a change to the inclination. If the mount is not level, then a change to one axis will also induce a slight change on the other axis. The magnitude of this change will be directly related to the amount the mount is off-level and the amount of change applied to the other axis. Note that you can polar align perfectly with a mount which is not level but it will definitely be frustrating in that a change to one axis will also change the other slightly, and you will go back and forth, hopefully slowly reducing the polar mis-alignment. Leveling the mount will allow you to work on one axis at a time and be done with polar aligning more quickly.


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jmiele
Patron Saint?
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Reged: 12/04/10

Re: The little leveling bubble on an Atlas EQ-G mount. new [Re: M13 Observer]
      #4518118 - 04/14/11 03:58 PM

Being initially level north to south and on following setups helps ensure little to no Alt adjustments. If you are level N-S and were when you set Alt originally, E-W leveling means nothing. It only affects RA which gets set at sync. Even your polar scope has to be manually moved in RA each night anyway.

IOW, leveling N-S is all thats necessary - ever...

FWIW.... Joe


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Zaphod
member


Reged: 11/21/07

Re: The little leveling bubble on an Atlas EQ-G mount. new [Re: jmiele]
      #4518703 - 04/14/11 08:44 PM

A guy in the local Astronomy Club would use a discarded phone book for altitude adjustment and could get micrometer accuracy very quickly.
-Bob


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Doug76
Long Achro Junkie
*****

Reged: 12/05/07

Loc: Refractor Heaven
Re: The little leveling bubble on an Atlas EQ-G mount. new [Re: Dmitri F]
      #4519341 - 04/15/11 01:59 AM

Quote:


In my experience, the aluminum tubes are thin and can be very easily dented by overtightening the adjustment bolts so I don't like touching them either.




The legs are steel. But they are a bit thin.


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