Setting circles on a CG4 mount

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Chris_Barlow
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Setting circles on a CG4 mount

Post by Chris_Barlow »

Can anyone please explain to me how to set the RA setting circle on a CG4 mount? (The instructions could have done with a diagram or two!)

I have the ring with the 2 scales on it going up to 24 (hrs?) with a short rectangular plastic scale that goes up to 10 and below that lot there's a flat disc with a scale on it up to 12.

Exactly what am I setting to what? I've followed the instructions which simply say to set the RA scale to the coordiates of a known star (regulus in this case)!

Many thanks for your help.
Bunny
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Post by Bunny »

Hello Chris,

I don't use the setting circles myself, but I have a similar mount to yours, the EQ3. In fact I believe the CG4 is Celestron's name for this mount.

You can download the manual from http://www.orionoptics.co.uk/acatalog/downloads.htm

The EQ3 manual is here:
http://www.orionoptics.co.uk/acatalog/E ... ctions.pdf

I hope that helps?

Good luck.
Chris_Barlow
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Post by Chris_Barlow »

Thanks again Bunny! :D

The Orion instructions make a lot more sense than the Celestron instructions!

Any idea what the date ring is for and how to use it? (That's if I need to?)
Bunny
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Post by Bunny »

Hello Chris, I'm glad that helped. :)

I suspect that the "date ring" is to do with aligning the optional extra Polar Alignment scope, although I am sure some kind soul will put me right if that is incorrect? :wink:

The pointers on my mount for the Latitude and Right Ascension are the same colour as the mount (sort of hammered enamel grey/green), so one little trick I used was to paint them sparingly with a little typist's correction fluid (Tippex). It doesn't affect the mount asthetically, and it is easier to see in the dark (though you are not going to alter the latitude much once set up) but the RA pointer is pretty inconspicuous at the best of times without doing this.

I have found a couple of links that may (or may not) explain using setting circles a bit more:


http://www.astroleague.org/al/astrnote/astnot13.html

http://astro-tom.com/telescopes/setting_circles.htm
Chris_Barlow
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Post by Chris_Barlow »

Thanks for the info & those links Bunny. :D

Is there something I'm doing wrong? I can set the RA to a known position but when I rotate the scope the circle turns about 1/8th turn then stops! If I tighten the locking screw the circle doesn't move at all. There seems to be a slot at the 0 hr position for the locking screw to locate in.

Do I set the RA circle then tighten the screw completely or just enough to provide friction to the circle or not at all? My friends mount is a CG 5 and is exactly the same.

Many thanks for any help.
Chris_Barlow
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Post by Chris_Barlow »

Help, anyone?

Please?
joe
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Post by joe »

Chris,

No screw tightening as far as I'm aware. My RA circle (Vixen GP) moves with the rotation when everything is loose but not when the little lock screw is in. Is your little screw all the way out? Can you attach a little piece of blutac or tape of some sort to the circle and axis to see if it's just a matter of it not staying with the axis?
200mm Newtonian, OMC140, ETX90, 15x70 Binoculars.
Chris_Barlow
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Post by Chris_Barlow »

Thanks Joe

I had another look at it last night. The screw is all the way out. It looks like it's just grease providing the friction to drive the circle from the axis!

I'll try a little more grease to see if that helps.

I'd really like to have it working if not just to learn & understand it. I'd like to have a go at spotting daylight planets too but don't really want a GoTo scope to do the brain work for me. 8)

Might join the local club and see if anyone there can take a look at it?
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