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Equipment Discussions >> Mounts

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ChadGray
sage


Reged: 04/09/10

Loc: North East Ohio
Celestron Polar Axis Finder Question
      #4076714 - 09/27/10 04:01 PM

Ok, i am reading the instructions on using the Celestron Polar Axis finderscope and have a question. I dont have the part in my hands yet so i am just reading the manual.

http://www.celestron.com/c3/images/files/downloads/1223669429_polaraxixfinder.pdf

After you rotate RA to get Big Dipper or Cassiopiea near their etchings you are supposed to use the AZ and ALT knobs to move polaris "inside the small circle".

Is polaris supposed to be dead in the middle of the circle? The illustration show polaris on the edge of the circle.

Thanks!
Chad


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rmollise
Postmaster
*****

Reged: 07/06/07

Re: Celestron Polar Axis Finder Question new [Re: ChadGray]
      #4076807 - 09/27/10 04:42 PM

Use the altitude and azimuth knobs as appropriate to get Polaris in the circle. In the middle of the circle.

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fatrowbridge
sage
*****

Reged: 06/11/06

Loc: UpState South Carolina
Re: Celestron Polar Axis Finder Question new [Re: rmollise]
      #4077037 - 09/27/10 07:01 PM

I may be completely wrong....but I think it may be get Polaris just inside the circle while the etchings match. Polaris rotates around the pole correct?

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DLB242
Mr. Warmth


Reged: 07/29/08

Loc: Pen Argyl, PA
Re: Celestron Polar Axis Finder Question new [Re: ChadGray]
      #4077064 - 09/27/10 07:11 PM

Quote:

Ok, i am reading the instructions on using the Celestron Polar Axis finderscope and have a question. I dont have the part in my hands yet so i am just reading the manual.

http://www.celestron.com/c3/images/files/downloads/1223669429_polaraxixfinder.pdf

After you rotate RA to get Big Dipper or Cassiopiea near their etchings you are supposed to use the AZ and ALT knobs to move polaris "inside the small circle".

Is polaris supposed to be dead in the middle of the circle? The illustration show polaris on the edge of the circle.

Thanks!
Chad




After making the adjustments as detailed the way I read it is Polaris in centered in the small off center circle not the X in the center of the large circle.

I have always just used the mark in the center, seems to get things close enough for reasonably accurate gotos. If I need better I can use the "Polar Align" function available through the hand controller of my CGEM. The CG-5/ASGT also has a "Polar Align" function built in to its hand controler.

Edited by DLB242 (09/27/10 07:50 PM)


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BlueGrass
Carpal Tunnel
*****

Reged: 07/25/09

Loc: Wasatch Front, UT
Re: Celestron Polar Axis Finder Question new [Re: DLB242]
      #4077155 - 09/27/10 08:10 PM

The older versions of the HC firmware had the Polar Align function. The newer firmware gives the CG5 / ASGT the ASPA feature. If you have the older firmware, you should update to one of more recent versions. Also, the latest version of the CGEM HC / MC firmware gives you the option to change the slew / goto RA / DEC speeds from the default 9 setting, allowing these mounts to operate quieter.

One thing to keep in mind about the PA scope, it needs to be accurately collimated before it's of any use.

Edited by BlueGrass (09/27/10 08:11 PM)


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ChadGray
sage


Reged: 04/09/10

Loc: North East Ohio
Re: Celestron Polar Axis Finder Question new [Re: BlueGrass]
      #4077240 - 09/27/10 08:53 PM

Thanks for the replies!

So the little circle on the center circle is where i need to stick polaris? The illustration i could not tell if the little circle was representative of polaris or an etched circle.

I have the old, old version of the hand controller. It is not upgradeable. I have to three star align then polar align then three star align again.

I am hoping that getting the mount physically aligned will help me with tracking and rely less on software.

Thanks again for the replies!
Chad


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DLB242
Mr. Warmth


Reged: 07/29/08

Loc: Pen Argyl, PA
Re: Celestron Polar Axis Finder Question new [Re: BlueGrass]
      #4077356 - 09/27/10 09:53 PM

Quote:

The older versions of the HC firmware had the Polar Align function. The newer firmware gives the CG5 / ASGT the ASPA feature. If you have the older firmware, you should update to one of more recent versions. Also, the latest version of the CGEM HC / MC firmware gives you the option to change the slew / goto RA / DEC speeds from the default 9 setting, allowing these mounts to operate quieter.

One thing to keep in mind about the PA scope, it needs to be accurately collimated before it's of any use.




Celestron still calls the method "Polar Align" in my CGEM manual same name used in my CG-5 manual. The technique has changed in that you can now use any star, where as with the CG-5 before the latest upgrade you could only use Polaris. And yes you most definitely need to align the polar scope for it to be an accurate aid. I never did since my polar scope is not a Celestron, it came from a Chinese clone that I picked up about 6 years ago no other marking other than the center X.


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ChadGray
sage


Reged: 04/09/10

Loc: North East Ohio
Re: Celestron Polar Axis Finder Question new [Re: DLB242]
      #4077387 - 09/27/10 10:20 PM

So the new HC is worth the $150? Can i not physically polar align with the Polar Axis Finder then use the older HC to three star align? I have the patience to use it and i dont see a huge advantage of ASPA when i have a perfectly good view of Polaris.

I will be guiding with PHD so i want my MC to be up to date with the latest firmware. So that is one upside to the updated HC.

I really don't care how quite the motors are.


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BlueGrass
Carpal Tunnel
*****

Reged: 07/25/09

Loc: Wasatch Front, UT
Re: Celestron Polar Axis Finder Question new [Re: ChadGray]
      #4077462 - 09/27/10 10:57 PM

Chad,
Hello. The accuracy of the polar scope with your CG5 will depend on how well it's collimated and how accurately you use it. Given those two areas, you can get a fairly good PA. The advantage of using the ASPA is that it uses your mount's alignment procedure results to compute where it thinks the star you use for the ASPA is. If your alignment is done accurately and the ASPA is done accurately, the results are considerably better then using a polar scope alone.

The slew / goto rate change I referred to only applies to the CGEM and I believe the CGE Pro. The latest I heard, it does not apply to the CG5. Hopefully, Celestron can update the motor control firmware for the CG5 to take advantage of it.


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DLB242
Mr. Warmth


Reged: 07/29/08

Loc: Pen Argyl, PA
Re: Celestron Polar Axis Finder Question new [Re: ChadGray]
      #4077578 - 09/28/10 12:34 AM

Quote:

So the new HC is worth the $150? Can i not physically polar align with the Polar Axis Finder then use the older HC to three star align? I have the patience to use it and i dont see a huge advantage of ASPA when i have a perfectly good view of Polaris.



I will be guiding with PHD so i want my MC to be up to date with the latest firmware. So that is one upside to the updated HC.

I really don't care how quite the motors are.




Chad, how old is your CG-5/ASGT? Before the CGEM I had a CG-5/ASGT that I purchased new in 2006. I sold the CG-5/ASGT and before shipping the mount to the new owner I used the NexStar RS-232 cable link that came with the CGEM to upgrade the Hand controller and Motor Control to the latest versions. Here is a summary of Firmware Versions for the CG-5/ASGT link Even if your mount is older you still may have the flashable hand controller and may not need to replace your hand controller just buy or make the RS-232 cable.


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ChadGray
sage


Reged: 04/09/10

Loc: North East Ohio
Re: Celestron Polar Axis Finder Question new [Re: DLB242]
      #4078002 - 09/28/10 09:23 AM

Thanks for the replies. I will consider getting the new hand controller. I want to see if my DEC drift is any better once i use the Polar Axis Finder. Some nights my DEC is dead on and other nights slowly drifts away.

I got the mount used, but i believe it is about 5 years old. If i remember right my hand controller is version 3.03. I called Celestron tech support and they said i could not update the firmware on my hand controller. I have the serial cable and that is how i am trying to auto guide with PHD.

I am also considering the NexRemote software that celestron sells that basically would give me all the new features of the new hand controller.

http://www.celestron.com/c3/product.php?ProdID=327

I am just not sure i want to control the telescope from the laptop. The hand controller seems more convenient to do the alignment procedures.


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Donnie D
professor emeritus


Reged: 03/21/08

Loc: Madison, Mississippi
Re: Celestron Polar Axis Finder Question new [Re: ChadGray]
      #4080836 - 09/29/10 02:43 PM

Chad,
The Celestron PS has been the best purchase for me so far. It DOES take time to set up the way it should be. It is NOT a plug and play thing. You have to set it up and it does take some time to do so.

I would like to help you, but remember that I am new at this too.

The Polar Scope (PS) does have some etchings on it. It has a model of cassiopea, the dipper, Oxtans, etc. Then it has the small cross hairs (cross) right in the middle. Do not make a mistake. The cross hairs are not to be used. The cross hairs right in the middle demonstrate for you where the REAL NORTH CELESTRAL POLE is.

Polaris is about 44' from the Real Celestral north pole.
OK, so when you look thru the PS, you will see a large circle. Now you will also see a TINY circle that is ETCHED on top of the large circle. That TINY circle that is off to the side, well, that is where you STICK the star polaris in. When you get polaris in that tiny circle, then you are accurately polar aligned "MECHANICALLY".

Well, there is MORE to this. That little PS has to be mechanically aligned first before you can really get accurate. I found out the hard way that I was VERY surprised that when I rotated the Mount in RA, that the etchings inside the PS MOVED !!!!

So, with that being said, what is going to happen is that you are going to have to take an allen wrench and make adjustments to the PS to make sure that the PS is circumpolar or is in perfect agreement centered as you rotate the mount. You might have to choose an object like I did in the daytime. I set my mount up in the house and pointed the PS at some object out the window.

Except that when you are making the mechanical alignment of the PS, THEN you have to center the object on the cross hairs. THIS IS THE ONLY TIME. You can use like a telephone pole or some object that you put dead center on the cross hairs. THEN the trick now is to MOVE your mount in RA about 90 degrees to the right and THEN look thru the PS and you will probably as I did see that the object you had centered is NO LONGER centered, but has drifted off some. Now swing your mount back to home and you will probably see that the object is now back to center on the cross hairs. Now swing your mount to the left RA and you will see that it is changed position. Now that you understand what is going on, then reach for the allen wrenches and loosen-tighten all three screws and align that PS so that when you turn your mount all the way around, the object in the PS STAYS CENTERED !!!! Then you will know that your PS is accurately tuned with your mount.

Then wait until about when you see Polaris start to pop its head from the evening and first of all, try to get your mount as CLOSE as possible to true north - mag north as you can get. Loosen your azmuth screws and your altitude lock nut and make sure all of this is loose. When you look thru the PS, hopefully you will see Polaris floating in there somewhere. IF you do, good, if you do not, MOVE the entire rig around until you see polaris show up ANYWHERE in the PS. Once you have Polaris in the PS, then adjust your azmuth screws and your alitude knob until you get Polaris inside the SMALL circle (riding on top of the big circle). DO NOT put polaris on the cross hairs. The cross hairs are your NCP (North Celesrral Pole). At this point, your rig should be MECHANICALLY aligned to the NCP. Polaris is just a reference. Yes, that 44' does make a difference and leveling the scope as accurately as possible makes a difference to.

You might also have to loosen the nut underneath the mount to help make the mount a little loose so that the azmuth screws will work easier. If the bolt on the bottom of the mount is too tight, you will never get the azmuth screws to move.
After all of this is done, then it is time to do the two star alignment and then add about 2 calibration stars.
Once you get the PS mechanically aligned using the allen wrenches, then for the most part, this will not have to be done again.

I have found that my GoTo's are very accurate. I did try last night the All Star Polar Alignment, and I guess I must have goofed something up, because I had to go back and do my Polar Scope routine again.

The above is mentioned as only my own personal experience - others may differ.
Donnie D.


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ChadGray
sage


Reged: 04/09/10

Loc: North East Ohio
Re: Celestron Polar Axis Finder Question new [Re: Donnie D]
      #4080869 - 09/29/10 02:58 PM

Thanks for the excellent answer Donnie! I got the finder today and it makes more sense now that i can see the etchings. The documentation was a little confusing.

Looks like i wont have the sky tonight to try it, but i will at least get it mechanically aligned to the mount tonight and hope for some clear skies this weekend.

Thanks!
Chad


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Donnie D
professor emeritus


Reged: 03/21/08

Loc: Madison, Mississippi
Re: Celestron Polar Axis Finder Question new [Re: ChadGray]
      #4080963 - 09/29/10 03:46 PM

The only thing that I wish was that Celestron could have put a small LED inside the PS. The etchings are not easy to see at night time. I am sure that there is a way to modify that to add an LED. In the meantime at dark, I can shine a RED light to strike across the Bore opening to illuminate the Etchings.

Donnie

Donnie


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Doug76
Long Achro Junkie
*****

Reged: 12/05/07

Loc: Refractor Heaven
Re: Celestron Polar Axis Finder Question new [Re: ChadGray]
      #4081891 - 09/29/10 10:36 PM

Quote:

So the little circle on the center circle is where i need to stick polaris?




Yes


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ChadGray
sage


Reged: 04/09/10

Loc: North East Ohio
Re: Celestron Polar Axis Finder Question new [Re: Doug76]
      #4082853 - 09/30/10 11:31 AM

I got it installed and mechanically aligned with my mount. Looks like Friday night i might be able to try it out.

Thanks for all the help!


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rcreek
member


Reged: 08/03/10

Re: Celestron Polar Axis Finder Question new [Re: Donnie D]
      #4088961 - 10/03/10 01:29 AM

From the manual: "Simply rotate your mount in RA until one
of the patterns matches its actual orientation in the sky."

How do we match orientation of Big Dipper or Cassiapeia's patterns if they are not in the PS's field of view when we point it towards Plaris?

Thanks,
John


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ChadGray
sage


Reged: 04/09/10

Loc: North East Ohio
Re: Celestron Polar Axis Finder Question new [Re: rcreek]
      #4090479 - 10/03/10 07:44 PM

I have only used it one night (dang clouds), but i could not really see the constellations match up with the etchings and i don't think that is what is supposed to happen. It would have to be a super wide lens in order to accomplish that.

You need to look at the sky and see where the big dipper and cassiapeias is in the sky and approximate where they are when looking through the finder.

My first use of the finder i found that as long as Polaris is on the line of the big center circle when you rotate RA, then you are polar aligned.

This is where wording comes in. When i say center circle i mean the circle surrounding the + sign witch is dead center of the finder.

Someone please correct me if i am wrong.

Chad


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skywolf856
sage


Reged: 01/25/08

Loc: SE Michigan
Re: Celestron Polar Axis Finder Question new [Re: ChadGray]
      #4111281 - 10/12/10 09:01 PM

I have the PS on my C6ASGT and I just recently updated my firmware.
I had it out earlier this week and after aligning polaris as described, my goto's were spot on!
I think the firmware update changed the motor rampup speeds because it sounds different than before.
I think it was a good addition at a low cost.


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skywolf856
sage


Reged: 01/25/08

Loc: SE Michigan
Re: Celestron Polar Axis Finder Question new [Re: skywolf856]
      #4111304 - 10/12/10 09:10 PM

Here's what I did for a polar scope LED.
This was originally created by Don Gallian.
Parts List

1. Radio Shack part number 276-299 ‘Blinking LED Module’ - about $3.00
2. 2 “AA” batteries – about $1.00
3. Plastic 35mm film canister – free


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