36 replies to this topic

[sw196060]

Considering strain wave mounts especially, are various mounts all equally sensitive to levelling, for accurate GoTos and tracking?

I have heard much about iOptron's mounts needing to be accurately leveled but are other mounts about the same?

 

Some mounts I am thinking about ... AZ31, i100, AM3 for example.

 

I assume similar algorithms are used by different companies but, there may be differences.

 

Thx

[wkight]

Keep in mind that leveling is not the same as polar alignment.  regardless of leveling once you are polar aligned correctly with the polar axis pointing where it should be, then who cares where your tripod is.  Leveling however makes it easier to achieve polar alignment by separating the Az and El adjustments.   If you are not level, then a change in azimuth will affect your elevation and vice versa.  Not the worst thing in the world, but it is just easier if you know that once you have that elevation just perfect, and you need to nudge to the left or right, then doing so won't mess up your alignment.  Leveling just simplifies the process.

Now if your polar alignment is off, that's another story.  Leveling won't fix that.

[Phil Perry]

Old fashioned "dumb" mounts certainly are all going to be quite sensitive to being non-level. Once you introduce things like plate-solving to figure out exactly where you're looking in the sky (in several directions), a smart mount can compensate for quite a bit of leveling error. Of course, you can give such things a helping hand by doing your best to level the mount, but no need to go overboard.

 

Note that a Seestar doesn't use plate solving to find the Sun (for solar observing), and I don't think it uses it to find the Moon, either. If your level is off noticeably, it won't be able to find either object.

[jmillsbss]

Just the way I understand it.... Modern plate solving will help if you're not level, or even pointed directly north, for that matter, but then the mount has to work harder in Dec to correct and track/guide properly.  Maybe your setup doesn't have plate solving capability.  You need to be more precise on your PA and pay more attention to the mount head being level.

 

I've pushed that little bubble all around the black ring and just about get it perfect and it jumps over to the other side!  It can certainly be frustrating.  I bought a larger level with more fluid and a bigger bubble that I can lay on top of the tripod before adding the mount.  It seems to help.  It's probably overkill, but I'm stuck on how important it is to get level.  It's just one of the first things that really stuck in my mind when I started doing this stuff.  I was told it was important, so I just do it.

 

So, if you can get level, get level. If it's off a tad bit, don't lose too much observing/imaging time worrying about it.   However, if you can get leveled and pointed to the CNP, your guiding will improve and your mount won't have to make such constant adjustments in Dec when tracking/guiding.

[sw196060]

I should mention that I am considering alt-az mode, not equatorial mode.   Thus, there is no polar alignment.

[JimTheEngineer]

Imaging or visual?

[wkight]

Old fashioned "dumb" mounts certainly are all going to be quite sensitive to being non-level. Once you introduce things like plate-solving to figure out exactly where you're looking in the sky (in several directions), a smart mount can compensate for quite a bit of leveling error. Of course, you can give such things a helping hand by doing your best to level the mount, but no need to go overboard.

 

Note that a Seestar doesn't use plate solving to find the Sun (for solar observing), and I don't think it uses it to find the Moon, either. If your level is off noticeably, it won't be able to find either object.

Yes, a seestar in its original az/el mode would be sensitive to leveling and uses plate solving to compensate it's tracking.  Better leveling means less compensation and better tracking.  But equatorial mounts don't have that problem when they are properly polar aligned.    Even a simple star tracker will work perfectly if it is polar aligned without regard to how its base is positioned.   Bolt it to the side of your house if you like; just get the RA axis pointing north (or south for those down under). 

 

The Seestar's equatorial mode is a huge improvement, and uses its plate solving ability to compensate for errors in polar alignment as it moves along.  I'm not sure how leveling would even impact a seestar in equatorial mode since the requirement is to get the thing pointed as close to north as possible while it is pointed "up".   I think they also ask you to have the power button oriented upwards, which would give it a rough idea of where things are based up the current sidereal time.

 

I apologize if I'm getting wrapped up in semantics.    

 

 

Edit:  I didn't see the post about az/el mode as I composed this.    Never mind..  

 

Another edit: I have the Romer Optics push-to encoders on my dob (fantastic option by the way) and I go to great pains to level the base so the encoders (electronic setting circles) are as accurate as possible

Edited by wkight, 17 April 2025 - 11:00 AM.

[sw196060]

Imaging or visual?

visual only.  

I just want decent tracking and GoTo.   I don't care about PE or minor tracking error.

The less fuss involved in setting up, the better for me.

[WadeH237]

I should mention that I am considering alt-az mode, not equatorial mode.   Thus, there is no polar alignment.

The mount should be pretty insensitive to leveling.  From a geometry standpoint, two known references (stars) is all any mount needs in order to orient itself to the sky.

 

If you think about it, your neighbor a few degrees of latitude south of you is tilted a few degrees relative to your mount.

 

I wouldn't worry about it.

[JimTheEngineer]

Ok visual. What is the telescope focal length? Will you have goto functionality (plate solving or just catalog)?

Edited by JimTheEngineer, 17 April 2025 - 01:37 PM.

[sw196060]

The mount should be pretty insensitive to leveling.  From a geometry standpoint, two known references (stars) is all any mount needs in order to orient itself to the sky.

 

If you think about it, your neighbor a few degrees of latitude south of you is tilted a few degrees relative to your mount.

 

I wouldn't worry about it.

Although the iOptron AZPro is an altaz GoTo mount and I have read that accurate levelling is very important for it.

[BGazing]

Although the iOptron AZPro is an altaz GoTo mount and I have read that accurate levelling is very important for it.

Accurate leveling is more important if you use point-and-track functions, i.e. one-star/planet align.

[WadeH237]

Accurate leveling is more important if you use point-and-track functions, i.e. one-star/planet align.

This makes sense.

 

As I mentioned, you need two reference points to orient to the sky.  If you are using just one object, then there needs to be some accurate reference to the ground.  With a GEM, once it's polar aligned, it can use the celestial pole for one reference and a single star for the other.  With an alt-az, a one star alignment mandates a known start position.

[sw196060]

So, doing two star alignment will mitigate levelling errors sufficiently?

[WadeH237]

So, doing two star alignment will mitigate levelling errors sufficiently?

You could say that.  I prefer to think of it that precise leveling is not a prerequisite to the mount working correctly.

 

Of course, the way to know for sure is to just try it for yourself and see what happens.  If you really want to be sure, purposely make the mount off level by 5 or 10 degrees and see what happens.

 

Let us know what you find.

[Cliff Hipsher]

Why all of the angst over leveling or not leveling a mount.  Just level it and be done with it.

 

Having said that, IMNSHO round spirit levels are worthless and the best way to level a mount is to use 2 "tube" levels at 90 degrees from each other.

 

 

[robbieg147]

I normally use a pier which I have set dead level, once I have polar aligned I don't need to plate solve as my target is very close to dead center. This is with a 90mm refractor, so to me it's worth having the mount level. If I want to slew to a bright star to focus it's in my FOV straight away etc.

 

Obviously this would not work with a long focal length scope.

[Phil Perry]

Why all of the angst over leveling or not leveling a mount.  Just level it and be done with it.

 

Having said that, IMNSHO round spirit levels are worthless and the best way to level a mount is to use 2 "tube" levels at 90 degrees from each other.

 

I think the debate here is how much effort to put into accurate leveling. 30 seconds of leveling with a round bubble level is going to be better than extending the tripod legs equally and saying, "good 'nuf, my beer can ain't tipping over." Two spirit levels (as shown) and more care to get within a fraction of a degree is going to be much better. Maybe not precisely enough for unguided AP, but within reason for plate-solving and compensation for minor off-level.
 

[sw196060]

Right. The question is how fussy do I have to be with levelling. I have used GEMs in the past and am very familiar with polar alignment.
I often move my rig a few times during a session so,
re-levelling is something I think about.

[davidgmd]

Right. The question is how fussy do I have to be with levelling. I have used GEMs in the past and am very familiar with polar alignment.
I often move my rig a few times during a session so,
re-levelling is something I think about.

  
For an alt/az mount, leveling does affect GoTo accuracy. How much effect leveling has depends on several factors:

1) How far are you moving?

2) How wide is your TFOV?

3) How big is your target?

 

  

If you’re using a short focal length refractor at low mag with a 4 degree TFOV, and the targets you’re moving between are large and relatively close together, say 20-30 degrees, being non-level isn’t likely to have enough of an effect to make you miss your targets.

  
If you’re using a long focal length SCT at medium or high mag with a 0.5 degree TFOV or less, and you’re moving 120 degrees to try to find a small target like a planet, being off level a couple of degrees will likely throw you off enough to miss that target.

  
Re-leveling is a pain if you’re moving the scope from spot to spot throughout the night. A rat cage adjustable leveler can make it easier and less risky than adjusting tripod legs with the mount and scope riding on top. I find a digital angle gauge easier to use than bubble levels. I line up the gauge with each tripod leg or adjustment screw on the leveler to get the mount level.

[WadeH237]

 For an alt/az mount, leveling does affect GoTo accuracy.

That has not been my experience.

 

The only alt-az mount that I currently use is a 14" Dob with a Nexus II.  I don't bother to level it, and it only requires two alignment stars.

 

I would imagine that orthogonality of the altitude and azimuth axes matter more than leveling.  If your axes are not very orthogonal, adding more alignment stars would improve performance.
 

[davidgmd]

You’re probably right, Wade. Unless youn use only 1 alignment star or depend on “level and North (or South)” for alignment.

[psandelle]

That has not been my experience.

 

The only alt-az mount that I currently use is a 14" Dob with a Nexus II.  I don't bother to level it, and it only requires two alignment stars.

 

I would imagine that orthogonality of the altitude and azimuth axes matter more than leveling.  If your axes are not very orthogonal, adding more alignment stars would improve performance.
 

The iOptron HAZs need really fine leveling (I mean, not morbidly so, but the more accurate the better) and they only have a one-star alignment. I wish they'd just throw into the software a two or three star alignment and be done with all that. Within a quadrant, it's not too bad off the one-star sync, but you're off even in wide-field if you move too far across the sky if you're not particularly level. Kinda sucks, though the extra leveling isn't a big deal. Still...just throw in another **** alignment star guys!

 

Paul

[Wildetelescope]

I should mention that I am considering alt-az mode, not equatorial mode.   Thus, there is no polar alignment.

Leveling is critical to all Alt Az goto mounts.  Leveling for GEM mounts is helpful but not critical.

JMD

[slavicek]

  
For an alt/az mount, leveling does affect GoTo accuracy. 

I also have to disagree. I have Meade, Celestron, Ioptron, Nexus, RST and who knows what other mounts... I use them in Alt-Az (for visual) and no matter what the manual says, the better I level them the better they perform. So the question is how good is good? That depends on your Max FOV (eyepiece FL & FOV versus  telescope FL). For example my DOB with 21 mm Ethos gives me True FOV 1 deg, so as long as Nexus points to within 0.5 deg I am fine. Then I center the object and I change to higher mag eyepiece. There's no free lunch, if you know what I mean.