How critical is leveling a mount if you then use a polar scope?

[DannyHarvey]

After watching a video on good pier designs they guy made a comment that the "rat box" (four leveling bolts with a plate atop the pier) was a waste of time and the leveling was done by the polar scope I was just wondering if any of you knew how this worked geometrically and could explain it in lay mans terms.

thanks

Dan 

[DannyHarvey]

ah ah, found the vid!

6:20 onwards...

[ollypenrice]

WIth a normal GEM there is really no need to level the mount in most cirumstances. On the majority of mounts it only does one thing, which is orientate the reticle on you polar scope correctly. It also reduces the interactions between refinements in RA and Dec as you close in on perfect alignment. Some software mount control packages will, I think, assume that you are levelled. Not sure about that though.

Takahashi mounts are pretty high end and cannot be levelled since their tripods don't adjust. They calibrate the polar scope reticle using a spirit level on the RA housing, which is far better. So there is no inherent need to be level ad no need to compromise a strong pier by ending it in flimsy levelling bolts as is often seen.

Olly

[DannyHarvey]

yes I see, that makes sense - the polar scope reticle needs to be level in order to calibrate with the current position of Polaris within the 2/3 of a degree circle.