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EQ6-R - Level the Tripod or the Mount?

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#1 ESzczesniak

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Posted 04 July 2020 - 10:25 AM

This is a little bit of a general question, but I’m asking it here since I’m trying to set this up for AP and this is common AP mount.

I have placed the tripod and carefully leveled it with a hardware store spirit level (checking orthogonal directions). If I then put the mount on the tripod, the built in circle/bubble level is not centered.

I don’t know how to check if that is “calibrated” to level though. So I assume I should level the tripod and ignore the built in level? Except what really matters is that the mount is held level. So if I knew the built in bubble level was accurate, that would be the most relatable. Thank you for any help/input.

Eric

#2 OldManSky

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Posted 04 July 2020 - 10:34 AM

Level the tripod.

The bubble levels on the mounts (all brands) are well-known for not being very accurate or reliable.

And you don't have to be obsessive about leveling -- just get it basically level.

 

You can polar align a non-leveled mount.  What "exact" leveling does (and ALL it does) is make it so that when you adjust azimuth, altitude isn't affected.  And vice-versa.  Not being perfectly level simply means that if you adjust azimuth, you'll "throw off" altitude a bit as well, and you'll need to make a new adjustment for that.  But since in reality "perfectly level" is almost never achievable, and adjusting either of the axes will mean adjusting the other one, there's no need to obsessively try to get perfectly level.  Close enough is close enough, and what really matters most is that the tripod is *stable* and won't move.  Not so much that it's perfectly level. :)


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#3 ESzczesniak

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Posted 04 July 2020 - 10:53 AM

I suspected the mounts level may not be great. Thank you for the reply.

Right now I just to get myself in the ballpark of polar aligned. Last night was unexpectedly clear, so I tried aligning it and had a bunch of issues. Not the least of which was we had some adult drinks during the day/evening. But I wasn’t anywhere closed to getting Polaris in the finder scope. And the finder scope was way to bright. Only messed with it for about 10 minutes before saying it wasn’t really the right night to try and sort this out.
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#4 sg6

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Posted 04 July 2020 - 11:01 AM

One other usually ignored aspect of levelling the mount as best you can is that when you set the Latitude scale to where you are located it should correspond to the angle of the RA axis and so make polar alignment easier to perform.

 

So Yes the mount does not need to be level but it is a lot easier if it is, and also makes more sense. Your 48 degree latityde setting may then match your 48 degree latitude. But you could save 2 minutes not bothering with levelling the thing, then lose 10 minutes attempting to get good polar alignment. Seems to be the preferred method that astronomers do.

 

The one other thing is - It makes you look as if you know what you are doing.


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#5 AhBok

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Posted 04 July 2020 - 11:07 AM

I leveled my mount 2 years ago when I put it in my dolly. I’ve not even checked level since. The main reason for leveling is so it does not tip over!
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#6 Peter Zbib

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Posted 04 July 2020 - 11:10 AM

Level the tripod. Takes 2mns and simplifies the polar alignment. Doesn’t have to be « perfect ».

Then do a polar alignment that is a good as required by your scope/camera/guider/exposure length require. That is essential. Again, perfection is certainly not required. You just have to make sure the unavoidable wiggling is undetectable

(I have never looked at the mount’s bubble)

#7 Peter Zbib

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Posted 04 July 2020 - 11:10 AM

Level the tripod. Takes 2mns and simplifies the polar alignment. Doesn’t have to be « perfect ».

Then do a polar alignment that is a good as required by your scope/camera/guider/exposure length require. That is essential. Again, perfection is certainly not required. You just have to make sure the unavoidable wiggling is undetectable

(I have never looked at the mount’s bubble)

#8 Huangdi

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Posted 04 July 2020 - 11:15 AM

Level the tripod.

The bubble levels on the mounts (all brands) are well-known for not being very accurate or reliable.

And you don't have to be obsessive about leveling -- just get it basically level.

 

You can polar align a non-leveled mount.  What "exact" leveling does (and ALL it does) is make it so that when you adjust azimuth, altitude isn't affected.  And vice-versa.  Not being perfectly level simply means that if you adjust azimuth, you'll "throw off" altitude a bit as well, and you'll need to make a new adjustment for that.  But since in reality "perfectly level" is almost never achievable, and adjusting either of the axes will mean adjusting the other one, there's no need to obsessively try to get perfectly level.  Close enough is close enough, and what really matters most is that the tripod is *stable* and won't move.  Not so much that it's perfectly level. smile.gif

+1



#9 SonnyE

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Posted 04 July 2020 - 11:25 AM

Hi Eric.

I'm old school, I believe in level and plumb.

I have always done my best to try and make sure my tripod is sticking straight up off the Earth I'm standing on.

That way, when doing an alignment, all the math in the mount has as level of a playing field to work from as I can humanly give it.

 

Many say it doesn't matter. But I take solace in trying to start out as best as I can.

 

Oh, and those bubble levels.... not a good reference. Lipstick on a pig. OK for leveling an RV, but not precise.

Trust your spirit level.

 

I use a digital level on a piece of heavy cold rolled steel as a bridge.  Just the head. (When I bought it for my shop the frames were extra.)

Called a Smart Tool, it gives me a 0.0 ° of accuracy. And I always check my tripod before I assemble my mount.

I use the legs as my axis for my checks. Once done, I can turn my level on the head of my tripod and find 0.0 ° of level, 360° of rotation.

At that point, I know I'm starting off as plumb as I can.

 

That way, I can be assured everything else is square and plumb as well.

It's a little extra step that I feel is well worth the effort.

 

While we are on the subject, you might find my levelers handy. Easily made yourself.

 

Mount levelers 4w
 
Mount levelers 3w
 
Mount levelers 2w
 
Mount levelers 1w

Edited by SonnyE, 04 July 2020 - 11:28 AM.


#10 KTAZ

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Posted 04 July 2020 - 11:51 AM

I level my EQ6R mount as follows;

 

1) I use a smartphone app called "Bubble". Yep, it is a bubble level. I set it on top the tripod to get it level. One thing I have found is that those tripod legs will spread a bit when you drop the head and weights on it, so once you have it set, push down on the top of the tripod plate a bit to get them to push out. Everytime you adjust a leg, make sure it is 100% extended horizontally away from the center by putting one hand on the tripod head and pulling the leg away from it. That takes 2 minutes.

 

2) I ignore the bubble level on the mount head. Worthless. That takes a nanosecond.

 

3) Before you load your counterweights, loosen your RA axis and turn it parallel to the gound, then use a proper spirit level on the shaft (magnetic helps) and lock your setting circle at 0 and tighten it down. Rotate it back and lock your axis 90 degrees from your level point and your RA home position is set. Takes another 2 minutes.

 

4) Unlock your Dec axis and rotate it parallel to the ground (I face the locking bolts away from me as that surface is flexible and not fixed). Use your spirit level again to get it level and lock your setting circle. Rotate it back and lock your axis 90 degrees from your level point and your DEC home position is set. Takes 1 minute.

 

Your done in 5 or 6 minutes and have a pretty darn good level perfromed. But, as others have said, it is not that critical for visual purposes. Some of us just like to be precise.goodjob.gif


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#11 ESzczesniak

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Posted 04 July 2020 - 12:11 PM

Thank you for the replies! I’m trying to form good habits. And first, the references for PA will start best from a leveled mount...particularly the altitude. And once I start guiding, a leveled mount should minimize needing to mess as much with DEC.

Quick question though on home position and RA axis. If I’ve done my ready correctly, the RA axis should be set to 6 hours with the scope leveled? And then unlock the clutch and move to 0 for home position?

Above mentioned 0 and I’m wondering if I’m mistaken.

I’ve leveled/aligned/zeroed the RA and DEC on a very level tripod on the garage. So these should be good to go once it’s dark.

#12 Francopoli

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Posted 04 July 2020 - 12:25 PM

I level the tripod.  Once the tripod is roughly level, I put the mount head on and tighten everything.  The bubble on the mount head is always off a little bit to the east.  Guiding and alignment don't see to e impacted.



#13 OldManSky

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Posted 04 July 2020 - 12:53 PM

Quick question though on home position and RA axis. If I’ve done my ready correctly, the RA axis should be set to 6 hours with the scope leveled? And then unlock the clutch and move to 0 for home position?

Above mentioned 0 and I’m wondering if I’m mistaken.

I’ve leveled/aligned/zeroed the RA and DEC on a very level tripod on the garage. So these should be good to go once it’s dark.

No to the RA question.

RA changes every second -- because the earth rotates, but the sky doesn't.  If you point your scope (or your mount's polar scope) at a particular spot in the sky, it will *at that moment* be pointing at a certain right ascension coordinate.  A few seconds later, if you don't move the mount or scope, the earth rotates and your mount/scope will be pointing at a *different* RA coordinate.  So you can't use RA coordinates to set zero position -- or any other fixed position.

 

Your "zero" position should be with DEC at 0 degrees (unlike RA, DEC doesn't change with earth's rotation), and your RA axis should be "straight up and down."  Not a specific RA coordinate.



#14 ESzczesniak

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Posted 04 July 2020 - 01:25 PM

No to the RA question.

RA changes every second -- because the earth rotates, but the sky doesn't.  If you point your scope (or your mount's polar scope) at a particular spot in the sky, it will *at that moment* be pointing at a certain right ascension coordinate.  A few seconds later, if you don't move the mount or scope, the earth rotates and your mount/scope will be pointing at a *different* RA coordinate.  So you can't use RA coordinates to set zero position -- or any other fixed position.

 

Your "zero" position should be with DEC at 0 degrees (unlike RA, DEC doesn't change with earth's rotation), and your RA axis should be "straight up and down."  Not a specific RA coordinate.

I understand that RA changes.  But doesn't the telescope expect to start in a "home" position to start any form of GOTO.  Obviously it needs to be aligned from there, but my understanding for most AP flows was to start in a home position.  Two or three star alignment are of course options too.  This scope is fairly permanently attached to the camera (field flattener, scew in imaging chain).  It seemed the sense I had for this was start at home, then GOTO the first target.  It'll be in a ballpark, 5-10 degrees perhaps.  Then plate solve to refine the position.  So I guess I shouldn't have used the word zero ever, but I was referring to setting a home position to start from. 


Edited by ESzczesniak, 04 July 2020 - 01:26 PM.


#15 TelescopeGreg

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Posted 04 July 2020 - 04:02 PM

Thank you for the replies! I’m trying to form good habits. And first, the references for PA will start best from a leveled mount...particularly the altitude. And once I start guiding, a leveled mount should minimize needing to mess as much with DEC.

Mmmm. not quite.  A level tripod is best for doing your polar alignment, as others have noted.  But once the mount is polar aligned, whether it was aligned from a leveled position or not, guiding will not be affected.

 

The only thing an un-level mount can cause is that the initial star alignment will be off, as the mount's "Home" position won't be pointing where it's supposed to be pointing.  Polar alignment is all about getting the RA axis to be exactly parallel to the Earth's, but it does not determine where in the RA circle it is in relation to the mount's fixed index marks.  Dec will be fine, but RA might be a little off.  That will all be taken care of during the Star alignment process, and after that, the mount's GoTo and tracking will be blissfully unaware that the mount wasn't level to start with.

 

And, as noted earlier, a really not-level mount can affect the entire imaging session.  When it falls over.




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