Polar scope, does it need to be on RA axis

[Davey-T]

As I'm getting a bit old and stiff I find it increasingly difficult to look through the Polar scope, especially kneeling on wet grass, so will either have to fit some sort of camera to it or right angle end.

But as there seems to be no need for the Polar scope to be through the RA axis (see EQ8, bolted on through several angles) I was wondering if It is feasible to use the ST80 I use for guiding with a Meade illuminated astrometric eyepiece and an App to find Polaris position ?

Will there be a problem with the guide scope not being perfectly aligned with the RA axis ? doesn't seem to bother SW set up on EQ8.

Dave

[steppenwolf]

A polarscope must be perfectly aligned with the RA axis or it will not work I'm afraid. The external ones like those on the EQ8 and Mesu 200 are a bit of a kludge that will get you in the right ballpark IF their mounting brackets are accurately aligned with the RA axis but accuracy will still suffer.

A great solution is to use a webcam mounted on the polarscop'e eyepiece - I have done this very successfully with my EQ6 mount and it certainly saves your knees, back and neck!

[perfrej]

I would say that a polar scope is not necessary at all. Just drift align and you will be all set. High end mounts do not use polar scopes, instead they rely on calculations made from the alignment stars you use.

Just point your RA towards Polaris with a green laser, pop an eyepiece in and point the scope east. Take it from there with a drift alignment routine and you're done

/per

[Alien 13]

I allways use one of these held against the polarscope eyepiece its simple and saves your knees and back..

[JamesF]

I see no reason why the polar scope would need to be concentric with the RA axis, certainly for the purposes most SGL members require.  I reckon it should work well enough anywhere.  The real requirement is I think that it be parallel to the RA axis.

James

[Alien 13]

I see no reason why the polar scope would need to be concentric with the RA axis, certainly for the purposes most SGL members require.  I reckon it should work well enough anywhere.  The real requirement is I think that it be parallel to the RA axis.

 

James

True some designs like the astrotrack use this method but one problen with mounting the scope off axis is to find a method of rotating it through 360 degrees whilst still being parallel to the RA axis.

[JamesF]

True some designs like the astrotrack use this method but one problen with mounting the scope off axis is to find a method of rotating it through 360 degrees whilst still being parallel to the RA axis.

Yes, I bet that could be a little tricky to do.  Not impossible, but probably not a doddle either.

James

[steppenwolf]

I see no reason why the polar scope would need to be concentric with the RA axis, certainly for the purposes most SGL members require.  I reckon it should work well enough anywhere.

It doesn't have to be concentric with the RA axis, just aligned with it.

[smudgeball]

Hi

I'm the same as Alien13

I only use my adapted right angle viewer to check alignment.

Yes it IS a waterbottle cap araldited onto the end (I used a spare "Nikon" adapter to connect)

Use Alignmaster myself and have always found it to be really good.

so the polarscope is there to check alignment.

Regards

Neil

[Davey-T]

I allways use one of these held against the polarscope eyepiece its simple and saves your knees and back..

Thanks for that idea (and Neil) got one of those never thought of using it, skies clear so will try it tonight.

Dave