Mount Balance

[Pluto]

Hi All just a quick question does the mount have to be level if your polar aligned or doesn't

it make any difference

[MartinB]

No

It makes drift aligning easier if it is level though - When properly at the eastern and southern meridians the drift will appear to be in RA and dec if the mount isn't level (you still only adjust RA though!)

[Dippus]

When you have done your polar alignment and 2 or 3 star align. Does your scope slew to your chosen targets accurately? I thought that it did so i'd say that the mount being level or not is not a problem.

[centroid]

No

Hmm, I'm not so sure about that. :?

Surely, even though the mount may be polar aligned, if it is not level, it cannot 'track' in the correct arc with respect to the Celestial Sphere.?

Dave

[Whippy]

Sorry Martin, but I have found with both my CG5 and EQ6 that having the mount level does help with the GOTO somewhat. Obviously having the mount polar aligned helps as well.....

Tony..

[ottUp]

"No" is correct in the technical sense, maybe not in a practical sense.

By definition, polar alignment means simply that the polar axis is pointed at the NCP (North Celestial Pole). If that is the case, the mount can be nailed to the side of a tree, it doesn't matter. And all motions of the mount (RA and Dec) are relative to this axis.

However, a more practical answer is that having the mount level makes it easier to become polar aligned. Compass & latitude alignment depends on a level mount. Polar scope alignment doesn't. Drift alignment is easier with a level mount, because the east/west and north/south adjustments interact if the mount isn't level, requiring more iterations.

- Richard

[RobH]

Yes

Level is where everything is measured from. If you try to polar align and you don't start off level, your alignment will drift off.

While this may only be a small effect, it will nonetheless be there.

In practical terms, for a portable setup it doesn't have to be perfect. For a permanent setup, get it as close as possible. Mine is level to within 1/10 degree...as close as I can measure it in other words.

Cheers

Rob

[Sam]

Mmmmm - this is an interesting question. Logically thinking about it, doing a polar alignment makes the mounts RA axis line up with the North/South celestial axis - which means the mounts movement in RA and DEC will be with the celestial sphere - no matter if the mount is level or not. Though I would imagine it would quite hard to properly balance a scope that was not properly level on the tripod/pier. Happy to be shot down in flames if I'm missing something .

Sam

[RobH]

Interesting discussion

Can't argue with the fact that if your RA and DEC are correctly aligned, the angle of your mount isn't important....you are effectively level anyway in that situation.

I suppose that in practice though, your equatorial head sits on top of your mount, either pillar, tripod or whatever.

If this isn't level then your equatorial head won't be capable of being properly aligned.

Take an extreme example for the sake of argument. If your eq head sits atop a pillar that is leaning to the east at 20 degrees, you'll have a hell of a time getting a good polar alignment

Then again...I could be wrong...the wife says I am often :D

Cheers

Rob

[MartinB]

The question was whether the mount needs to be level provided if it is polar aligned - the answer is no it doesn't.

Not having it level makes it trickier to drift align, and messes up positioning through the polar alignment scope.

The EM200 has a spirit level on the RA axis. The mount can be put down at any angle. When the RA position is adjusted using the spirit level the reticle in the alignment scope is in the correct position for polar alignment. Once aligned the angle of the mount doesn't matter.

It's a bit counter intuitive.

[Pluto]

Thanks all now i can put my mind to rest cheers