Celestron Advanced VX Mount woes

[migeek]

I’m somewhat new to things but have been somewhat successful with my current setup

• Explore Scientific 80mm ED APO 
• Celestron Advanced VX Mount
    
• Canon 450D DSLR (modified) w/Astronomik UV/IR clip-in filter

I’ve read the manual for my mount at least a half million times, read forums and have had some text based assistance from a couple of friends. (They live elsewhere) and I feel bad constantly pestering them.

I’m looking for some help on understanding my mount a little more. I set it up in the same spot every night I’m out, point the weight pole North (toward Polaris), turn it on, I originally entered my longitude and latitude coordinates (using the Compass App on my iPhone), time, date, time zone, etc.

The next time I set up, same spot point the weight pole North toward Polaris, just enter the updated date and time and do a two star alignment.

After doing this it seems that my go to be only accurate for certain objects in the sky and a certain percentage of the time. I can go to Orion’s Nebula, Sirius, Horsehead and Flame, Moon… all centered… Try to go to Bode’s Galaxy, Andromeda Galaxy or Globular Cluster, etc and it’s not even close to the object.

It seems that maybe it’s only accurate in the Southwest sky?

Am I missing something? Should I be doing more star alignment? Let me know if anyone has any help or ideas, any and all help is greatly appreciated! Thanks!

 

[knobby]

Very weird ... All I can think of is maybe poor balance and slipping clutches maybe 

[migeek]

Hey knobby,

Thanks for the reply, I balanced it to the best of my ability, the single 11lb weight is maybe just a couple inches from the base of the mount. I have my ES 80mm ED APO, Canon 450d, Orion 50mm guide scope and my Orion SSAG as well. It feels pretty evenly distributed, any suggestions for testing proper balance?

I did have an issue with one of my clutch knobs pointing down a few weeks back and when it would track it would rub on the motor housing and unlock itself. I adjusted the knob and that appears to have resolved that issue but still having the goto accuracy issues. 

Thanks!

[aparker]

Hi,

 

I have both AVX and CGEM mounts.  The two key things I have found are 

1. Get the polar alignment really good.  I have my CGEM on a pier so it is always set up the same.  For the AVX, which I use on the tripod, I use a digital inclinometer to get the altitude of the RA axis dead on.  It is quite helpful.

2. Always do at least two calibration stars after the two star alignment.  The Celestron software will pick calibration stars on the opposite side of the meridian from ypur alignment stars, which makes for a much better all-sky model.

[migeek]

Hey aparker, Thanks for the reply!

Crap, I don't think I've done any calibration stars... Or if I have it has always been manually throughout the night. I'll definitely be sure to do the calibration stars after the alignment stars. could you elaborate on the digital inclinometer and the altitude of the RA axis?

Thank you!

[migeek]

Also for anyone that happens upon this post inquiring about the Celestron Advanced VX fix I did for the clutch knobs, see the attached picture (simply unscrew the screw in the handle re-adjust the knob and then screw it back down)

When it was locked the knob would go below being flush and then when the mount rotated, it would disengage the clutch and the mount would stop moving/tracking properly, after the fix when engaged the knob doesn't cross the plane to rub on the motor housing anymore.

[PeterCPC]

Have you updated the firmware? It does make a difference.

Peter

[james_screech]

8 minutes ago, PeterCPC said:

Have you updated the firmware? It does make a difference.

Peter

What ever you do don't update the firmware, the latest is full of bugs, especially with PC control of the mount.

James

[Rob Kenning]

Just to clarify what James stated.  You need version 5.25.4320 for your handset

5.28.5300 version has serious errors especially with connection dropouts on the serial USB cable.

[PeterCPC]

The OP does not mention using ASCOM to control the Mount so the latest AVX update should be fine. I have just updated mine with no issues. Version 5.25.4320 is the one to download.

Peter

[migeek]

Hey Rob, PeterCPC and and james_screech,

Thanks for the help!

 

I haven't looked into updating the firmware at all, not even sure what version the mount is on.  I'll definitely get version 5.25.4320 downloaded and installed on the mount to see if that helps, Thanks!

[aparker]

22 hours ago, migeek said:

Hey aparker, Thanks for the reply!

Crap, I don't think I've done any calibration stars... Or if I have it has always been manually throughout the night. I'll definitely be sure to do the calibration stars after the alignment stars. could you elaborate on the digital inclinometer and the altitude of the RA axis?

Thank you!

Sure.  I use a little device called an angle cube made by iGaging.  I bought it for woodworking originally.  You place it on a surface and it reads the angle of that surface relative to horizontal to 1/20 degree precision.  I use it by placing it on the mount saddle and adjusting it to exactly my latitude.  That way I know I have one paramater set right, and just have to adjust the azimuth to point at the NCP once it is dark.  Gets me a good-enough polar alignment in just a couple minutes.

[migeek]

Added calibration stars tonight, for about the first half hour things seemed great until I tried going to an object in the North or Eastern sky, lost all accuracy, yet if I selected an object in the South or West coming back around it was almost spot on... I have verified my latitude using an app on my phone and laying it in the saddle, so I'm almost positive that isn't it. It's supposed to be warm and clear the next few days, hopefully I can figure it out. Thanks for all the help and suggestions so far everyone!

[migeek]

Ok, so last night I did a 2+4 and did an All Star Polar Aligment, it seemed to GoTo on objects a little better, it was definitely in the vicinity of the object I selected but still not 100% accurate... Gonna try one more time tonight and then try updating my firmware.

[Joel Shepherd]

I don't think I've ever gotten what I'd consider to be 100% accurate goto alignment ... for whatever reason my AVX seems to land a little southwest of the target. But the target is always in the eyepiece with moderate magnification and bringing it to center is trivial. Is your alignment much worse than that? Also, are you using a reticle eyepiece? If not, I'd try that before risking a firmware upgrade (and strongly recommend it regardless). If the alignment stars aren't consistently centered in the eyepiece, firmware won't help.

[migeek]

I had a friend over last night to show him my whole setup and what it takes to run it... Last night must've been the night. I checked the weight pole was pointing (North-ish) toward Polaris just like I do every night,  I re-entered everything, did a 2+4. I explained to him the troubles I've been having, I was showing him things I could GoTo that I know have worked in the past and just for giggles we punched in M66 (Leo Triplet) and sure as crap... IT SLEWED TO THE TRIPLETS!!! Dead center!

It's only been one night that I have been able to verify this, so I'll try to get out again soon to make sure it wasn't a fluke night. Nothing really changed, I did everything that I normally do?

 

[PeterCPC]

Perhaps you just did it more accurately.

Peter

[Grotemobile]

My CG-5 mount is the same . It has to be level, & pointing north. Get

it right & it tracks & finds objects, very good. Get it wrong  

1 hour ago, PeterCPC said:

Perhaps you just did it more accurately.

Peter

 

[Gazabone]

I got an AVX 18 months or so ago and absolutely hate it....long story which I won't bore you with but the only reason it's in the attic now is that I can't quite bring myself to put it out for refuse collection. 

Might be worth checking the encoder motors. In day time, set it up with a scope (balanced etc but don't worry about alignment). Turn off the tracking and centre the scope on a static target. Take a note of the altitude and azimuth coordinates (you can find them within the menus on the handset). Then slew away using the handset (if possible in Dec and ra 180 degrees) and then slew it back to your static target and centre. Take a note of the coordinates. If one or the other are radically different (particularly if there's a consistently increasing error with one or the other as you repeat the exercise) then you have an encoder problem and it's a case of sending it back to Celestron. 

Before doing that it might be worth running as normal but using a different power supply, I think the AVX is a bit fussy. 

[Grotemobile]

Have any of U tried, to just do a planetary align . That is what I do. I use Jupiter.

Then do a sync, on the planet.  Never done a star align yet.  This works very well.

[migeek]

Sorry to hear that Gazabone, I sometimes feel like I'm in the same boat. I'll keep trying for a while and see what I can figure out, sucks I have a handful of friends with the same mount and swear up and down. 

 

Grotemobile, I'll give that a try, I have tried a planetary alignment but never did the "sync"

[SonnyE]

As a rule, I have always done a 2+4 alignment procedure. To me, doing my best to do my part to ensure accuracy is important. If they gave a 2+ more, I'd probably do more.

I suppose I might be a little anal about it, but anytime I move my mount I check that the tripod is as level as I can humanly get it. To do that I use a digital level and it reads to .1 degree (1/10th degree). I always fidget until I get 0.0 degrees on two planes. My thinking is to remove as much human error as I can. One one-thousandth of an inch here on Earth can mean a lot of error at the distances we want to look over.

I have two spots in my backyard (Garden to many of you Chaps) where I have dedicated spots for my mounts toes to index to. That assures it lands in the same spot when moved due to weather changes/rain. Generally, I will leave my mount set up from night to night and only bring in my telescope assembly and laptop used for imaging. The mount gets covered with a waterproof canvas plus a 32 gallon plastic trash can (bin) for total weather assurance/Sun screening.

It's not that I am lazy, but that the mount left undisturbed will be more accurate the next night or so when I again return to it. And I always check to see the feet are undisturbed.

Relatively lately I have learned to do a Polar Alignment after my 2+4 alignment. Here again, trying to fine tune the mount. If after the first one there is any error left, I will do a second to get Zero's on the check. Reference: http://www.celestron.com/university/astroimaging/all-star-polar-alignment

Yet, even after all of this, there seems to be a bit of hit and miss with targeting. But I can live with that, after all this is considered an "Entry Level" mount. And like I said, 0.001" can mean a miss when aiming at an object thousands of light years away from a spinning blob of Jell-o.

I have always thought giving my AVX a guide scope was paramount to giving it an "eye on the sky". Without a guide scope, the mount bobbles and wobbles about at the mercy of mechanical imperfections in the gearing. I made a 7 second time-lapse demonstrating my AVX's guiding without a guide scopes help. You are welcome to view how the mount acts unguided: https://youtu.be/2rOOZ9Hu8_0

Because I got into Observing with it in mind to do astrophotography, I leaned towards the most stability I could do within my budget. So I strive for the little steps, and don't expect miracles. I've recently learned I'm actually an EAA type of backyard (Garden) bloke. At my age, I like the conveniences of home and my bed being close.