Mount levelling & the EQMOD polar alignment procedure

[HAL9000]

I know there's another thread on level (or not) platforms & tripods, but I want to clarify:

I think I understand the argument for not worrying about the mount being 100% level, once it's polar aligned. However to get polar aligned in the first place, would having an un-level mount affect the accuracy of the EQMOD polar alignment (or other automated methods)?

For example - following the Youtube instructions you place polaris in the cross hair & move it to (for example) 12 o' clock on the circle, using the DEC bolts. Then, does the automatic rotation & bolt adjustment to re-position polaris in the circle still result in an accurate alignment, even if the mount isn't level? I think it would... Presumably the initial adjustment to 12 o' clock would be to 12 o' clock relative to the mount itself - so even if the mount was on its side, you would still only use the DEC bolts, which would actually move polaris to 9 o' clock relative to the ground, but 12 o' clock relative to the mount - so the next step would still polar align the mount?! I hope that makes sense!

I've possibly just answered my own question but please can someone agree or if not explain why! Thanks!

Chris

[JamesF]

My understanding is that if you're going to use such a polar alignment method then it helps to have the mount as level as possible because the software assumes that moving (for example) the az adjusters will only rotate the mount horizontally.

You'll probably get there if the mount isn't level, but it may take a few more iterations.

James

[HAL9000]

Thanks, I'm currently half way through building a pier & trying to decide how silly I need to get about making the top level, as I'm planning to use the EQMOD method (at least to begin with) and want to make sure it's accurate.

[ollypenrice]

On a permanent pier I would just drift align. It is very easy and very, very accurate. You'll only do it once every blue moon anyway. For this method the mount needn't be even remotely level. The thing is, you see lots of whacking great piers ending in three spindly threaded bars to get the mount level, which it doesn't need to be. If getting it level doesn't cause you to compromise the strength of the pier then fine, but if it does then just drift align.

Olly

[HAL9000]

Thanks Olly. I've never really explored drift aligning, always thought it sounded complicated & I don't have an eyepiece with crosshairs. Although is there any software that can help by putting crosshairs on a live camera image? Also my view is fairly limited, I have good horizons to the south & south east, OK to the north, & a small area of west (not completely to the horizon). East is mostly blocked by trees. Would drift aligning be possible without good horizons?

[Freddie]

CCD to Align Your Scope.pdf

Give this a go.

[ollypenrice]

Lots of people use the guide prgramme PHD to drift align with cameras. I use Artemis Capture which can throw up a crosshair, as can Nebulosity. I bet most capture programmes can do this.

Olly