How critical is it to have a mount and tripod level?

[bluesilver (Peter)]

Hi, I just thought i would ask this question and get some advise and opinions.
On my previous Skywatcher mounts i have adjusted each tripod leg up and down slightly to get a spot on level tripod and mount.

The thing is, where i image and view, the concrete ground ( driveway ) is at about a slope angle of 3.3 degrees.
It might not seam much. but it is quiet a bit if you are trying to level something up.

So i have got a larger tripod and also a larger mount now, the mount is classes as a center balanced mount, but pretty much is a German Equatorial mount, It is a iOptron CEM120

So the question i am asking is:
How critical is it to get a mount perfectly level for imaging?
I realize you need the best possible polar alignment you can get.

Can i get away with it sitting at a 3.3 degree angle? or is it still best to wind up and down the legs to get it spot on?

I feel that as you wind or adjust any tripod leg away from their home position, they will be less stable.

But any advise would be appreciated.
Thanks.
Peter.

[Stonius (Markus)]

When your mount builds a model it will take into account small errors, but the bigger the errors are, the more the compensation is required, and it's not perfect. The best results are gained when starting from as near as possible, a flat surface.


Markus

[Startrek (Martin)]

From my experience I’ve found accurate levelling on my EQ6-R does help with polar alignment where you only need minor adjustments in Alt and Az to align as poor levelling would lead to more time on those PA bolts.I also find your first slew ends up closer to the first alignment point ( Star ) that’s if you use an alignment pointing model like EQMOD ( don’t know about plate solving , don’t use it )
For bigger payloads it’s makes to sense to level as best as possible for improved stability.
With my 12” Goto Az Alt Dob , I find if I don’t level accurately the Goto’s are definitely not as accurate as when I take time to get the base accurately levelled
up.
With my EQ mount it’s not “critical” more best practice to level accurately
With my AZ Dob it is critical to level accurately
Cheers
Martin

[bluesilver (Peter)]

Thanks for the advises, appreciated.
It would seam then, that it is best to level the tripod then.
I might take a look at making up some wide wooden chocks or something similar as 3.3 degrees is a good amount of distance if the legs of the tripod are about 1 meter apart.

[Peter Ward]

Just to be crystal clear on this old chestnut: a tripod can sitting at almost any angle (well... apart from upside down)
and it makes absolutely NO difference to its tracking, provided the mount is accurately polar aligned.

The only advantage of levelling is you remove "cross talk" from azimuth and altitude adjustments. A non-level mount/tripod will induce a shift in both
altitude and azimuth, even though you may only have adjusted one or the other.

With a few iterations it is easy enough regardless of a level tripod or pier, to zero in on the pole.

[LewisM]

Originally Posted by Peter Ward

Just to be crystal clear on this old chestnut: a tripod can sitting at almost any angle (well... apart from upside down)
and it makes absolutely NO difference to its tracking, provided the mount is accurately polar aligned.

The only advantage of levelling is you remove "cross talk" from azimuth and altitude adjustments. A non-level mount/tripod will induce a shift in both
altitude and azimuth, even though you may only have adjusted one or the other.

With a few iterations it is easy enough regardless of a level tripod or pier, to zero in on the pole.

Exactly

[peter_4059 (Peter)]

+1

[bluesilver (Peter)]

I really appreciate all this advice.
I have yet to actually put all this into practice with this new mount, (waiting on weather conditions here)
I have heard and read of people saying don't worry about it being level, just make sure you have it polar aligned good, and some saying to get it nice and level.

I think i will put it into practice, just leave it as it it ( not level ) and get a good polar align.
I am driving the scope all via a laptop, so no hand control, I take it this will not be a issue?
Just slew to a few targets in Stallerium and sync it each time.
For polar alignment, i am using SharpCap.

All sound correct so far? Sorry if i am going back over things that have been discussed many times before on here though.

[gregmc (Greg)]

To restate the crosstalk in a different way:
If the tripod is level, when sharpcap says move left or right, that’s all that happens. If not level, you will get up or down movement which will knock that adjustment out.
Same for alt (up/down). If not level, moving up or down will also move left or right.

[The_bluester (Paul)]

To agree, but expand a little based on the mount you have.

For a polar aligned mount the tripod level CAN be functionally irrelevant, polar aligned is polar aligned. Having the little brother to your mount though (I have a CEM70G) I would suggest if you can get the tripod pretty level at least on the east/west axis it has some advantages. the "Find home" function homes the mount accurately enough that I don't need to mess around with a blind plate solve at the start of the night or otherwise risk plate solve 2 timing out trying to get the first plate solve, I start my night by seeking the home position and go right in to imaging from there. It reliably goes pretty close to putting the target somewhere in the field of view straight out of the box.

If your tripod is out of level east/west by a significant amount you may loose that advantage as the home position will not be where it is assumed to be (Shaft vertical with counterweights down, pointed at the pole) It is really handy if you manage to get things all in a flap at any time in the night as you can remotely seek the home position and be good to go again. I image from inside the house mostly unless I have company to drink whiskey with so not having to go out there to re set a starting position is handy.

[raymo]

Prior to modern GoTo mounts it really didn't matter much. I had an early
orange tube C8 which even stated in its users' manual that levelling was
unnecessary.
raymo

[kens (Ken)]

Originally Posted by bluesilver

Thanks for the advises, appreciated.
It would seam then, that it is best to level the tripod then.
I might take a look at making up some wide wooden chocks or something similar as 3.3 degrees is a good amount of distance if the legs of the tripod are about 1 meter apart.

Personally I would not use chocks, wooden or otherwise. The most important thing is that the tripod and mount are very stable and immobile. 5 microns movement at 1 metre equates to 1 arcsecond.
And to make setting up easier the more consistently you can set up the tripod the better. I drilled indentations into the concrete to locate the tripod feet. Others have glued washers and so on. If you mark the shortened leg position or even e.g. tap in a screw for a hard stop then when you set up each time you wil be much closer to polar aligned.

[AdamJL]

Originally Posted by Peter Ward

Just to be crystal clear on this old chestnut: a tripod can sitting at almost any angle (well... apart from upside down)
and it makes absolutely NO difference to its tracking, provided the mount is accurately polar aligned.

The only advantage of levelling is you remove "cross talk" from azimuth and altitude adjustments. A non-level mount/tripod will induce a shift in both
altitude and azimuth, even though you may only have adjusted one or the other.

With a few iterations it is easy enough regardless of a level tripod or pier, to zero in on the pole.

^ this

I try and be level, but eyeball level only. If you're polar aligning, plate solving and autoguiding, well it doesn't matter.

[JTomba (Julian)]

Great advice all, thanks!

[Hemi]

“How critical is it to have a mount and tripod level?”

A: for an eq mount, as others have said, not at all. Makes PA easier.

A2: for an AZ mount, it is very important for accurate gotos and tracking. If it’s very out of level, alignment will nearly always fail on an AZ mount.

Cheers