Polar Alignment Scope madness

[kens (Ken)]

Is it me or is every southern hemisphere polar alignment scope reticle etched incorrectly? Mine has the Octans "trapezium" etched into it along with pointers to Eri-a and Cru-a. But Eri-a is shown as being at the projection of an imaginary line from tau Octans through sigma Octans, and Cru-a is roughly in the opposite direction. According to every star chart I can get my hands on, the directions to Cru-a and Eri-a are reversed. So I began to think I had a strange, wrongly etched reticle. Maybe even a rare once-off error.
I then started to look up on the www to see what other scopes have on their reticles. A search on "octans reticle" came up with a few hits and every one that had the Cru-a and Eri-a pointers has them the wrong way around. Admittedly they may have all come out of the same factory but even then there must be a lot of incorrect reticles out there. (Not that it really matters other than to a pedant like me). Has anyone else noticed this?

[mithrandir (Andrew)]

Originally Posted by kens

Is it me or is every southern hemisphere polar alignment scope reticle etched incorrectly? Mine has the Octans "trapezium" etched into it along with pointers to Eri-a and Cru-a. But Eri-a is shown as being at the projection of an imaginary line from tau Octans through sigma Octans, and Cru-a is roughly in the opposite direction. According to every star chart I can get my hands on, the directions to Cru-a and Eri-a are reversed. So I began to think I had a strange, wrongly etched reticle. Maybe even a rare once-off error.

Have a read of the instructions for Losmandy's polar scope and see if it makes things any clearer. Make sure you read all the way to the bottom because the old reticle was only good to 2010 and the new one is good to 2030.

http://www.losmandy.com/pdf/polar-finder.pdf

[kens (Ken)]

Originally Posted by mithrandir

Have a read of the instructions for Losmandy's polar scope and see if it makes things any clearer. Make sure you read all the way to the bottom because the old reticle was only good to 2010 and the new one is good to 2030.

http://www.losmandy.com/pdf/polar-finder.pdf

Ahhh... I think I get it. Eri-a and Cru-a are not visible in the scope. So when you lift your head to find them to roughly align, they are no longer inverted and appear in the orientation you saw on the reticle. Or I guess the right idea is to roughly align with both eyes open.
What I was trying to do was to set up the setting circle by using the position of Cru-a and wondering why it came out all screwy. I'll use sigma Octans instead for that.

And yes I do need a new reticle anyway. Given the age of my gear (c. 1983) I doubt it was good to 2010 even

[PeterEde (Peter)]

My skywatcher one works a treat

[raymo]

My SW one is useless, illumination is much too bright, and can't be turned down. In my case it's all academic anyway, my poor old knees wouldn't
let me use it.
raymo

[PeterEde (Peter)]

Pull the batter Raymo?
I can see the stars without being illuminated.
and put a bucket under ya bum to sit on

Can I get better than 2 minutes with it? and at 2 minutes I seem to be tossing every 2nd image due to slight trails but 1st images no trails?
Hmmm Maybe I'll crank it up to 3 and see if the same thing happens

[mithrandir (Andrew)]

Originally Posted by raymo

My SW one is useless, illumination is much too bright, and can't be turned down. In my case it's all academic anyway, my poor old knees wouldn't
let me use it.

The late and much missed Barry Gerdes put a webcam on a polar scope scope so it could be operated from his computer. You can probably find the thread and images somewhere in the discussions.