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themos

EQ6 polarscope: can it be moved?

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Hello,

I've noticed that although the + in the middle of my polarscope reticule stays on a star as I swing in RA, the whole reticule does a very eccentric turn. I think that means that the polarscope is not aligned with the RA axis and as a result the reticule has been adjusted to be right on the edge of its allowed travel. Is there any way of moving the axis of the polarscope itself so that its optical axis is closer to the RA axis?

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Sounds like a bad bit of etching to me OR its your eyes playing tricks. If the + marker at the centre stays true on a star as you swing through the RA then the polaris circlke must by definition also stay true unless the circle is itself not printed accurately on the reticule.

If the reticule were off centre then the + mark wouldnt stay true either I would have thought.

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The eccentricity you are referring to allows the + to be concentric with the true RA axis. I believe the adjustment is included by design to allow for what would otherwise be extremely difficult to achieve: perfect alignment of the polar scope bore and the RA bearing.

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This is normal when the polar scope is not correctly aligned, there are 3 small allen bolts just below the scale that are used to adjust the polar score.

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I think the circle is cetred on the + alright.

It's just that the polarscope's optical axis is so out of true with the RA axis that the reticule had to be adjusted all the way to the left, say. When I take out the polarscope eyepiece I can see the reticule jammed against the sides. The + is some way from the centre of the tube.

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Gaz, I know the 3 small Allen screws that move the reticule. Are you talking about ANOTHER 3 Allens?

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brympton, yes, I understand. I wondered if there is a gross adjustment of the polar scope axis beyond the fine adjustment of the reticule.

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You're right Themos, the scope isn't true to the RA axis and can be adjusted using the bolts I mentioned. Its an easy job to to in the daytime with the latitude set low enough so a terrestrial object can be used as a target to check for monement of the 'x'. It can be a bit of PITA at night though....

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brympton, yes, I understand. I wondered if there is a gross adjustment of the polar scope axis beyond the fine adjustment of the reticule.

Ah!! No theres not to my knowledge. Those screws are used to centre the 'x', the scope is fixed in IIRC.

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Surely if the + remains on a star following rotation of the RA then it is in alignment or am I missing something here? If the reticule can be adjusted to achieve this then regardless of its final position it is concentric and within tolerance.

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Surely if the + remains on a star following rotation of the RA then it is in alignment or am I missing something here? If the reticule can be adjusted to achieve this then regardless of its final position it is concentric and within tolerance.

Yep, thats my understanding of it.

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The + is pointing at the RA axis but the apparent wobble of the whole view as the RA axis is rotated was disconcerting and unwelcome, that's all.

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