Jump to content

30sec_exposures_2021.jpg.48851b1871a4bf9500ebd53c3e790d81.jpg

 

 

EQ6 polarscope: can it be moved?


themos
 Share

Recommended Posts

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?

Link to comment
Share on other sites

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.

Link to comment
Share on other sites

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.

Link to comment
Share on other sites

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.

Link to comment
Share on other sites

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....

Link to comment
Share on other sites

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.

Link to comment
Share on other sites

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.

Link to comment
Share on other sites

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.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.