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Celestron Advanced VX Mount


dawson
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Had a play around with this mount today as a friend came over with it:


 


http://www.firstlightoptics.com/celestron-mounts/celestron-advanced-vx-mount.html


 


http://www.firstlightoptics.com/user/Celestron_Advanced_VX_brochure.pdf


 


It feels like a quality bit of kit. Very light, but feels very sturdy. Appears to be able to carry 30lbs (14kg) so is similar to the HEQ5 in that regards.


 


It doesn't come with a polar scope which surprises me, but there is emphasis on using the All Star Polar Alignment (APSA) which is a feature now on the latest versions of the firmware from Skywatcher, and which some of us have had success with and others not (I was in the 'not' category but I think I had other issues at the time I tried it).


 


I had an HEQ5 polar scope in the garage which luckily fitted like a glove so we installed that and aligned the reticle so hopefully that will help him polar align pretty accurately; we had to remove the silver collar from the polar scope with the numbers on as this was stopping the cap being put back on to protect the polar scope, but otherwise you won't know it wasn't sent out from the factor like this.


 


Anyway, I will be interested to see this mount being used at night. It looks like serous competition to the HEQ5, and a really nice mount.


 


James


 


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Cool looking piece of kit. What is the all star polar alignment function of which you speak? What version of firmware on he handset is that on? I think I'm behind on this???

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V3.35

After a two or three star alignment the SW handset gives you Mel and Maz errors (errors in the elevation and azimuth; correcting these errors apparently gives perfect polar alignment). There's a function on the handset to do a routine to reduce these errors to refine PA, i can't remember what the function is called, maybe something simple like "polar alignment"!

I couldn't get it to work when i tried it, but i think stephen got better results.

Jd

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Guest ecopley

Having a play with the polar alignment routine this evening. No stars visible at all so unable to actually do it but, for those who have yet to try, the plan is that, after roughly polar aligning, you do the two star alignment then go to the polar alignment routine (press align and scroll down to 'polar align). You pick a star from the list, which the scope slews to and then you correct the error, if any, by moving in alt and az rather than ra and dec. This should put you bang on within the limits of the mount. Sounds suspiciously simple...

The celestron website says that it will distort your two star alignment a little but presumably if your polar alignment wasn't far off then it shouldn't make too much difference.

Shame it was cloudy all night.

How frustrating!

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With the skywatcher version of this, i think you then do a fresh star alignment after you have fiddled with the alt-az knobs, to make sure tour GOTO is as accurate as possible (and also could use that second star alignment to re-check rhe polar alignment and if necessary repeat it and make it even better (again, ending with a star alignment)).

When i tried the skywatcher version, i found it took enormous rotations of the alt and az bolts to centre the target star, and i knew then it wouldn't work as i had already done a pretty good polar scope polar alignment, and was just expecting to do the smallest of turns of these knobs to refine it. I like the technique on paper though, and if the next version of the skywatcher firmware mentions this having been updated, i'll give it another go. I will be interested to see the celestron version in action.

Ed, do you have an illuminated reticle eye piece to make sure you are always putting the target stars bang on in the centre of the fov?

Jd

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Maybe skywatcher just haven't got the software side of their version as accurate as Celestron have, but several people i know have tried the skywatcher one, and i'm only aware of stephen who has had any success with it.

Jd

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Guest ecopley

I do indeed have an illuminated reticle eyepiece. I realised I would need one for aligning properly but the most useful thing I do with it is align objects so they will fall within the fov of a webcam chip. Took a while to work out why I could find anything with my web cam. Much easier now. Same with the oag.

When I can see some stars I will do a visual alignment and see what the error is in the celestron system.

I will also do the pec on my mount and then take some pictures to see which method gives the tightest stars. I know neither will be perfect but interesting to find out if the extra step makes things any better I think.

Watch this space!

T.

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Hmm, i think i see the reason. With the cge one does a minimum of 2 star align, can do 5 star but thats pontless if you are going to shift axes during the routine. You then select polar align roitine and it points the scope at polaris. You then adjust axes fine adjusters to get polaris smack in the middle of a reasonable mag ep then pres enter. Then you have to recalibrate the mount with 2 or more calibration stars. This is because you have shifted the mount from your first calibration. E.g think of the second recalibration as fine tuning after polar aligning. The cge is deadly accurate then, puts objects in the middle of the ccd whichever side of the meridian you choose, also drift is negligable, ive done drift aligns after performing the routines and not had to adjust much.

Would a realign after running the pa routine improve things i wonder

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Philjay, i can only comment on the skywatcher version; the ASPA routine on this celestron mount may be excellent, i've not seen it in action yet, but want to.

Yes, ending the routine with a new star alignment is recommended in the SW one as the GOTO will be off if you've altered the alt or az knobs. Though it was the PA which was dreadful when i played with this, not the GOTO accuracy. I should have a third go with it sometime and just check i wasn't doing something wrong.

Your mount sounds significantly more intelligent and accurate than mine. It's interesting that yours asks you to centre polaris. I can't get my head around how that works with the mounts axis aligned with the NCP, and the scopes axis aligned with Polaris.... Mind boggling :)

Yesterday we looked at the CGE mount online and marvelled at it. I hadn't previously appreciated how advanced that mount is; i've always been blinkered into think Skywatcher was "the daddy" but this clearly isn't the case.

Jd

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Maybe skywatcher just haven't got the software side of their version as accurate as Celestron have, but several people i know have tried the skywatcher one, and i'm only aware of stephen who has had any success with it.

Jd

Somewhere I have picked up the idea that the Celestron system is better...

As an relatively inexperienced newcomer I have to say I have been drawn to some of the Celestron products including this mount.

Gut feel is that Celestron are slightly ahead in the Tech Game....

Is this me being fooled by the Published Hype or Fact?

Ade

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Guest CodnorPaul

I love Celestron kit - and debated over an AVX or an NEQ6.  In the end I chose the NEQ6 as it carries a heavier load, but is also quieter than the old CG5 and also meant to be quieter than the AVX, the noise on my old mount got on my nerves so the quietness appealed to me.  That said the Celestron software was better, and the AVX gets great reviews most of the time (some initial teething issues).  I am lead to believe the CGE mount is also louder than the NEQ6 but it is meant to be better.


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"Is'nt Kim selling one like this??"


 


Ron I recently sold a CG5GT Goto which was the predecessor to the AVX. I'm also selling a 300P Flextube dob with full goto - someone has first dibs on it at the moment. :)


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Ron, is your EQ5 you do the polar alignment routine on the one on the pier? Is it spirit level, level? I did wonder if not being level had contributed to my bad experiences with it.

Jd

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Guest ecopley

Totally bone but no visible stars here again so no experiments for me.

On the other hand, I've been playing with astrophotography tool which someone recommended in reply to my 'hello' post.

Genius. Really really great. Can see myself using that a lot! So today I attached my DSLR to apt and my zwo to phd, put both on my oag, added an extension because the zwo wouldn't focus and now, if only there were some clear skies I'd take the aforementioned avx outside and find out the answers to all the questions.

As it is, I'm sat staring at it and occasionally confirming that it's pointing at Orion using astrotortilla. It is, in fact, not pointing at Orion. It's pointing at the inside of my house. But it doesn't know that because I confused it. Tee hee!

Clear skies and an astro-onesies for everyone!

Yay!

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Guest Kheldar

As dawson mentioned, I've had considerable success with the 3.35 PA routine - not sure what the differences are but I can get a 30min sub in the bag with one iteration of the routine


 


When setting up I normally start from a reasonably correct latitude and bang on North - being level matters not one jot but I do it anyways :)


 


With the NEQ6 for the first alignment star I used to drop the clutches to get the star reasonably close then refine with the handset, I don't do this with the EQ8 as the encoders inform the handset what I'm up to anyways :)


 


When the three star is complete I do a couple of GOTO\s just to make sure the target stars are at least in the FOV - you should not expect pinpoint accuracy, but so long as you can see it in the FOV then you know you haven't messed up an alignment star (like using Procyon instead of Pollux ... not that I've ever done that :whistle: )


 


When it comes to getting the PA star - make sure you read the instructions. The rough process is


  • Use the handset to get the PA star on target (I recommend using something E or W about 45 degrees up if possible)
  • Confirm this, let the mount slew away then use only the Alt bolts to get the star (and here's the important bit) AS CLOSE AS POSSIBLE (not bang on) to the centre of the FOV (bearing in mind I'm not using an EP, I use a computer with a crosshair :) )
  • Alt adjustment should not normally be a huge one
  • Confirm this then repeat for Az adjustment only
  • Az adjustment should normally be a huge one as if you've set up due N like me, then NCP is about 2/3 degrees off to one side)
  • If you're using the handset then you need to 3-star again at this point. As I use the PC at this point I park, power off and switch to the EQDir cable
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Guest Kheldar

Thanks Stephen, i'll give it another go; you make it sound easy, and 30 minute subs sounds appealing :) Presumably that is 30 minutes guided?...

Jd

 

30 minutes guided yes, but that's with zero field rotation (the bit that you see even with guiding and crap PA)

 

If the dark sites ever drain I can run through it with you, see if it behaves any better for me? :)

Edited by Kheldar
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Guest Kheldar

That would be kind, as i've like the principal, just always had shocking results.

How well do you think it compares to drift aligning?

Jd

 

It's not as good, drift aligning is easily the best method ... however I'm crap at that and it takes me much longer :)

 

Another thing on the list for me to learn and get better at, along with using Focus Max ... removing user error is always good :D

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I've just downloaded the manual for the CG-5GT mount as someone is coming over today with one for me to "help" them with polar aligning... Substitute "help" for "hinder" maybe :)


 


Interestingly, at the bottom of page 32 / top of page 33 (http://www.telescopes.com/images/pdf/CELE054.pdf), it talks of the Polaris method of Polar Align. This method would not be very accurate with my Skywatcher mount and any of my telescopes, as the RA axis of the mount and the optical axis of the scope have never been perfectly aligned (the old cone error saga. Aligning Polaris in the centre of the optical axis of the scope would mean it would be hit and miss where axis of the mount was pointing. I guess it depends on how accurately he wants to be polar aligned; I think he wants to play with DSLR imaging, so it needs to be as accurate as possible; if there is no polar scope fitted, I might suggest he gets one.


 


JD

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