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Celestron CGEM: ASPA vs. Polar finder

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#1 Strosek

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Posted 19 March 2013 - 04:23 PM

Hello to all. I've got one question...
Has someone test the polar alignment precision using the Celestron All Star Polar Alignment ASPA in comparison with the polar finder?
Can I use ASPA for long exposure photo or should I prefer the polar finder aligment?
My setup is Celestron C9.25 @ f6.3 on GEM guided with Orion 80/400 scope mounted in parallel.
Thank you to all

#2 rmollise

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Posted 19 March 2013 - 05:04 PM

AllStar is usually better.

#3 Mike X.

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Posted 19 March 2013 - 06:17 PM

I use only ASPA (or AllStar) and i must say don't do drift star alingment anymore ;)

#4 orion69

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Posted 19 March 2013 - 07:37 PM

If you are imaging just use ASPA and forget polar finder.

#5 WarmWeatherGuy

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Posted 19 March 2013 - 08:20 PM

I use both. The polar finder gets you pretty close right off the bat. If I am only imaging the planets or doing visual only then that is all I use.

To use ASPA I do the 2 star align + 4 calibration stars. Then I look to see what my polar alignment is. It is usually about a quarter to a half a degree off. Then I do the ASPA, turn off my telescope, and start all over. This may take a few iterations to get the alignment perfect - depending on how close you want it to be. The polar finder saves one iteration so it is worth it for that.

I wouldn't want to be without either one.

#6 beckemd

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Posted 20 March 2013 - 07:51 AM

ASPA is that only Celestron mount compatible? what of an orion atlas eqg? Or is this program to be run off your PC, irrespective of the mount...?
DBB in Chicago

#7 orlyandico

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Posted 20 March 2013 - 08:32 AM

my experience with ASPA is that drift alignment is still superior.

i guess if you use widely-spaced stars ASPA would be more accurate, but i don't get to use widely-spaced stars most of the time.

beckemd - ASPA is only for celestron Nexstar and Nexstar+ hand controllers. it is basically an assisted polar alignment routine (like Alignmaster) but fully self-contained in the handset.

i understand that the latest Synscan firmware also has a similar feature - though called something else.

#8 jrcrilly

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Posted 20 March 2013 - 08:50 AM

my experience with ASPA is that drift alignment is still superior.


Sure. For visual use, though, it's plenty accurate and, for me, much more convenient than a polar alignment scope. ;)

#9 rmollise

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Posted 20 March 2013 - 12:33 PM

my experience with ASPA is that drift alignment is still superior.

i guess if you use widely-spaced stars ASPA would be more accurate, but i don't get to use widely-spaced stars most of the time.

beckemd - ASPA is only for celestron Nexstar and Nexstar+ hand controllers. it is basically an assisted polar alignment routine (like Alignmaster) but fully self-contained in the handset.

i understand that the latest Synscan firmware also has a similar feature - though called something else.


Not sure what you mean by "widely spaced stars". ASPA only uses ONE star.

The ASPA routine is present in several Synscan (EQ-6, etc.) betas and one release. It is still under development, but I expect a finished version soon. It is exactly the same as ASPA (Celestron is, afterall, owned by Synta).

#10 Footbag

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Posted 20 March 2013 - 12:43 PM


Not sure what you mean by "widely spaced stars". ASPA only uses ONE star.


He must mean the initial stars. The first alignment stars generate a pointing model and then the ASPA star just uses the pointing model to calculate the offset.

#11 Whichwayisnorth

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Posted 20 March 2013 - 12:50 PM

I don't have experience with the CGEM but with its little brother the Advanced VX I have had insanely good results with ASPA. The other night I did a 2 alignment plus 4 calibration routine. Then I did the ASPA. Finally I wanted to do a drift alignment. The drift alignment method I used was the built in part of BackyardEOS where it records the movement of the star so you can see the drift. I meant to come back in 300 seconds (5 minutes) but lost track of time and came back 1014 seconds later (almost 17 minutes) and the star was exactly where I left it. Unfortunately I had to take everything down at the end of the night due to an impending storm. Suffice it to say I was really impressed.

#12 dickbill

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Posted 20 March 2013 - 03:43 PM

I have a finder on my cgem and i will say like all: ASPA

Although the finder is not useless. It helps to get close and that matters, because as easy and fast the ASPA routine is (provided you did everything correctly before), you will appreciate to make small corrections in altitude and azimuth rather than big ones.

#13 orion69

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Posted 20 March 2013 - 04:35 PM

my experience with ASPA is that drift alignment is still superior.


There is nothing more precise then good drift alignment.

But since ASPA was good enough for 30 min subs (at least for me) I'd say it's quite useful.

#14 Strosek

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Posted 22 March 2013 - 05:09 PM

Thank you for all your replies.
Usually I follow this procedure:
Alignment 2+4 stars
ASPA
Power cycle
Alignment 2+4 stars
For visual use It is fantastic: I can remove the finder because all the objects will be for all the night in the eyepiece.
My dubts are on photography. I often see blurred stars and I don't understand if the reason is the polar alignment or something else. So, in your experience, for long exposure photo (each shot 5minutes) the ASPA routine can achieve good precisioni for avoid blurred stars in photo also using C9.25 @f=6.3 guided with Guidemaster and Orion 80-400?

#15 orion69

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Posted 22 March 2013 - 05:54 PM

Personally I wouldn't waste time imaging with C9.25 on CGEM. Sorry if that sounds too harsh.
But if for some reason I do, I would at least use OAG instead of guiding scope. IMHO

#16 RTLR 12

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Posted 22 March 2013 - 07:12 PM

Personally I wouldn't waste time imaging with C9.25 on CGEM. Sorry if that sounds too harsh.
But if for some reason I do, I would at least use OAG instead of guiding scope. IMHO


http://www.youtube.c...h?v=_VrFV5r8cs0

#17 WarmWeatherGuy

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Posted 22 March 2013 - 07:30 PM

I heard the advice to start out with a fast and short focal length scope but I didn't heed it. Instead I started out with an f/10 C8 on a CGEM. The CGEM is very capable and I didn't really have any problems.

I use Precise Goto. It goes first to a star nearby the target. I then center the star in the eyepiece and then use the camera and center the star in the middle of the screen. I also focus using a Bahtinov mask. Then I let the scope move on to the target. Originally I did not have a guide scope so my stars were streaked. Once I added the NexGuide Autoguider with a C5 for a guide scope I stopped the stars from streaking. The included picture was one of the very first astro pictures I ever took (without and then with a guider) and it shows you can use a long focal length to start out - if you have a nice mount.

Attached Files








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