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Celestron VX mount: experiences and problems

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#1 SunBlack

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Posted 30 August 2013 - 02:28 AM

See at http://www.cloudynig...5613234/page... for my first doubts and problems.

So:
1) the RA clutch lever doesnt secure properly the RA axis: even if i tighten the bolt, the RA axis turns (if i put a bit of pressure by hand). How to fix?

First night negative.
I just went with AP setup (canon 5d+300mm), unguided for 2 minutes at celestial equator. No ASPA, nor calibrating stars, tried to use the polar scope only, setting it on (roughly since no hour rings on mount) to what Polar Finder software indicates about Polaris position. Probably this inaccurancy led to trailed stars. (Used 1 star alignment. Goto was pretty accurate. )

Tomorrow, if no clouds, i would try again with polar scope, at about 11pm LT, when i saw on Polar Finder, Polaris will be a 9 hour Clock.

2) Skymap has the Ha Polaris data, how to calculate the Polaris Clock data? (i installed Cartes du Ciel but it gives me only Ha Polaris data too)

#2 cn register 5

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Posted 30 August 2013 - 04:06 AM

1) Balance the scope.

2) Use ASPA

Chris

#3 SunBlack

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Posted 30 August 2013 - 04:21 AM

If i'd use the ASPA: consider that on my home backyard i have limited portion of sky.
I see north, (little) north east and north west, no west, no est, South and south west (limited to 30° alt).
So in these conditions, could i try and succeed with ASPA?
In these conditions, how to choose right 2+4 stars?

#4 cn register 5

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Posted 30 August 2013 - 06:14 AM

South is fine for ASPA.

If you look at the sky you can see which bright stars are visible to you. A planisphere can help with identifying them, or there are smart phone apps.

Choose those for the align stars and the first calib star, it will be easier to be sure that you have the right one. After the first calib star the pointing should be good enough that later stars are in the EP. If the scope isn't looking at the sky then try a different star.

I think you may be over analysing this, it's worth practicing with the mount and HC indoors to become familiar with how it works but really just get outside and have a go.

Or get StarSense. I've been beta testing it in a more obstructed location than you describe and it was fine.

Chris

#5 SunBlack

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Posted 30 August 2013 - 03:15 PM

Real-time: how to change long and lat coordinates instead of preset cities? I goto to view time-site menu, go to cordinates but cant change anything.....

#6 cn register 5

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Posted 30 August 2013 - 04:16 PM

press undo when you get to the time prompt, this gets to the setting latitude and longitude pages.

Chris

#7 SunBlack

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Posted 31 August 2013 - 04:11 AM

Second night: success (partial, according my standards).
No way to have a good tracking with polar scope.
So i went for a 2+4 than ASPA. A long procedure i'd say.....since even with Skymap software is difficult/long to understand where is located the named star indicated in the HC. Then, i tried one PEC session via HC.....better tracking but no so much. Finally i tried a sequence of 5 PECs by PC, and results are in line with what i obtained with my ex Vixen GPDX.
I think that if my accurancy in guiding during PEC sessions will be improved (i remember i dont use autoguide and so my guide is manual), taking more care about what keys i'd press if the guiding star move i.e. left or right in respect of eyepiece reticle, i could obtain even better results.

Results:

No pec, 10 exposures

2 extra trailed
3 medium trailed
1 low trailed
4 good
-------------
1 pec, 10 exposures

3 extra trailed
2 medium trailed
2 low trailed
3 good
--------------
5 pec, 6 exposures
(2min at 300mm FL + Canon 5D)
6 good
--------------
5 pec, 4 exposures
(2min 15s at 300mm FL + Canon 5D)
2 low trailed
2 good



#8 SunBlack

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Posted 02 September 2013 - 01:50 AM

Last night new sequence of PEC (this time 4 iterations) with (previous) best-aligned polar witnessed (used eyepiece illuminated reticle)
4 pec, 4 exposures (2min 15s + Canon 5D at 300mm FL)
4 good

#9 SunBlack

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Posted 02 September 2013 - 04:33 AM

Some questions now:
1) What could be reason i had to correct frequently on DEC? ASPA inaccurate?
2) My Firmware versions are: HC: 5.22.3141 MC: 7.08.3071, should i upgrade something?
3) On Aligning and GOTOing, there's a feature that after pointing a star west to meridian, on going to a second star at east of meridian, i can avoid that the mount twists on itself, and goes to second star passing in front the meridian, doing "less road"? (my english is bad, i know)

#10 Dr.Don

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Posted 05 September 2013 - 11:54 AM

I bought my AVX 3 weeks ago and have had nothing but problems with it.

I set the index marks and have manually polar aligned using the bore hole or polar scope over several nights.
I balance the scope although both axes seem stiff. The mount almost always finds the first star (Arcturus) and sometimes the second star (Vega). Even if it finds Arcturus and Vega, it sometimes cant find its way back to Arcturus. It has never found a calibration star (Altair), missing by 5-15 degrees.
It won't consistently find Arcturus and sometimes misses the second alignment star by 5-10 degrees.

The RA motor sounds fine.
During a large slew the dec motor is OK at first but then starts a slow decrease in RPM's over a few seconds. It sounds like what you expect if a battery was running down but I power it from a 15 Amp supply.
The right arrow button sometimes moves the scope smoothly but other times it doesnt move at all. I can hold the arrow key down or give it several pushes. After several seconds the mount will make a quick jump like it was in high speed slew mode and sometimes put the object out of the EP.
The other 3 buttons always work.
Factory reset did not solve the problems.
At least the RTC keeps the correct info.

If it were not for the problem with the right arrow I could be convinced I'm not doing the alignment correctly.

The Orion store is 10 minutes from my office. The mount goes there today.

Don

#11 rmollise

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Posted 05 September 2013 - 12:32 PM

1. Always use a fully charged 12-vdc battery or Celestron's 5-amp AC supply.

2. Don't worry about it "finding" stars, don't worry about how far away they are from where the scope stops. Just center them up after it stops.

3. Make sure you center the correct stars. "Almost" ain't good enough.

4. Don't obsess over the axes being "too stiff." That won't affect go-tos at all.

;)

#12 Dr.Don

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Posted 05 September 2013 - 01:20 PM

I am using a high quality MFJ 15 Amp supply. There is no reason to change.
If it can go from Arcturus to Vega and then cant get back to Arcturus there is something wrong.

The dec motor issue is enough reason to return the mount for replacement. And I have another 8 days left in my 30 day money back guarantee so the whole C9.25 could find its way back.

#13 rmollise

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Posted 05 September 2013 - 02:45 PM

Not "going back to Arcturus" would be expected if there is a problem with your alignment/procedure to begin with.

#14 Dr.Don

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Posted 05 September 2013 - 03:38 PM

Alignment procedure:
1. Balance
2. Reasonably good polar alignment using the polar scope from my C8.
3. Set index marks.
4. Turn on, hit Align.
5. It usually get pretty close to Arcturus.
6. Use arrow keys to center in finder, hit Enter.
7. Use arrow keys to center in EP, hit Align.
8. Repeat with second star as selected by the HC.
9. See if it properly tracks the second star.
If it tracks the second star, select another object. One night it actually made it to M13 and another night to M57. But most times it couldn't find Altair, Alcor, or Arcturus.

If tracking or slewing fails, turn off power, go back to step 1 or 2 and repeat until frustrated. Then go into the house and let my son try it himself several times. Guess what? He gets the same results.

Since I am still within the 30 day window the very nice folks at Orion have ordered a new scope for me. I just have to pack up the whole telescope and bring it back to Orion.

Don

#15 rmollise

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Posted 05 September 2013 - 06:03 PM

If you are not doing the calibration stars, your go-to accuracy will be limited.

#16 Stew57

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Posted 05 September 2013 - 07:32 PM

I don't know if you are doing this but always finish with up and right when aligning. Add at least 1 calibration star. GOTOs should be fine. I will say I had one CGEM that Celestron had me test over and over and finally replaced it because it just wouldn't point. The replacement is dead on!

#17 schluterdude

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Posted 05 September 2013 - 08:15 PM

I never bother with hitting "enter" in the finder first. I get it centered in the eyepiece then hit enter the align. I also use all 4 calib star slots. Lethal accuracy.... I also use a 12mm EP during this on an 8" f6 reflector...

#18 Gary Minder

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Posted 05 September 2013 - 08:30 PM

IMHO if someone isn't doing a careful 2+4 before deciding a mount can't accurately Go-To then getting another mount may not be any less frustrating.

#19 seawolfe

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Posted 06 September 2013 - 04:36 AM

Agreed.

You HAVE to do a 2 + 4 and it's very plain on the handset that you press Enter after centering on the finder scope and then Align after centering in the EP.

Using a medium power EP or better yet, a illuminated reticle helps greatly in the EP alignment.

That said, I know from experience to have the scope well balanced, have the Rec and Dec locks ON... Have the correct latitude alignment. Have the correct time, day, time zone and type of time... i.e. DST vs. Standard time.

Next, first and second alignment stars will NOT be spot on, but you have to move the scope to it using the arrow keys. Use Up and Right to keep the backlash down.

#20 schluterdude

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Posted 06 September 2013 - 05:48 AM

Running the mount calibration/ra switch routine helps as well. And the "precise goto" function if you are strapping on accessories/running at the high end like I am... My OTA with rings/dovetail/camera tips the scales at 27 lbs... It's rated for 30, and I can hear the ap'ers groaning at the 50-75% rule!!!! Someday I'll get a monster ;-)

#21 MartinTreadgold

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Posted 06 September 2013 - 07:29 AM

Yes, one of my friends ask me what she should buy her boyfriend as a present, i suggested that he should take up astronomy, she thought it was a great idea, so she went out and bought him an AVX mount and C8 as a present, lucky guy..

But... he didn't like it because, he only wanted to look at the stars from his balcony, he lives in the worst light polluted places on earth, right next to a steel works in the Netherlands, he didn't want to travel out to friesland, or the dutch islands to get out of the light pollution, and, the balcony was not sturdy, so it vibrated and shakes every time a car drove past in the street, or when he walked about on the balcony, hence knocking it out of alignment. Because of the light pollution, he found it too difficult to align, you are lucky if you can even see vega. He didn't understand what a complex piece of scientific equipment it is, and that you have to really travel with it, and make an effort to use the thing properly

Now he has taken it back to the store to get a refund, the ungrateful muppet... I think she should dump him, take the scope off him, and date me instead lol.

Moral of the story, (which is true btw), the mount is only as good as the effort you put into aligning it.

My AVX has been fantastic so far, but the accuracy is only determined on how accurate you are in aligning it. Can't stress enough how important it is to centre those stars perfectly. I have yet to buy a reticle eyepiece, it is on my shopping list..

I do have the Skysync GPS, and that is a really useful thing to have, it improves the accuracy and saves a lot of time.

So Reticle Eyepiece, Skysync GPS, 2 star + 4 Calib stars and the ASPA routine should be good every time.

The thing is, if you read too much into the forums about the AVX.. you will see too many negative comments, as people only tend to post when things go wrong. You don't hear about the many thousands of people who have this mount and it works brilliantly. So don't read too much into the negative stuff.

It takes time and practice to get a mount to be accurate, don't expect to get it 100% on the first few goes, it is only as good as you are with it.

Practice Practice and Practice is all i can say

Best Regards

Martin

#22 Dr.Don

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Posted 06 September 2013 - 01:49 PM

This is a description of the problems I am having with a new C9.25/AVX.

First: I take time to balance the scope. I precisely follow the process in the manual. The appropriate clutches were released and engaged again as directed. I do a stationary balance first then push on the scope in both directions to see if it moves more easily and farther in either direction. I do this for both axes and several times. My C8 is much more sensitive to being out of balance. I have had it for 20 years, I know my way around the sky and I know what objects I'm looking at. The only time I manually move the scope is to align the index marks with the power off. I use a high quality 15 Amp power supply and I checked the voltage while running the scope. It's fine. I verified my location, local time, time zone, DST and offset from GMT are correct. I have done 2 factory resets. I do not have any accessories.

Second: The scope is level. I have done a visual polar alignment by putting the tripod down pointing roughly north, or looked through the bore hole, or used a polar scope. I have done all variations/combinations of these methods. As expected, there is no difference in how the scope behaves.

Third: I can use the HC to move the scope in all 4 directions very smoothly. Then it stops responding to the right arrow button. I can push it multiple times or hold it down. After 1-3 seconds it suddenly slews at high speed in that direction like I had done a GOTO. The slews used to be smaller but now many of the slews take the object out of the FOV. Then it will respond normally again. This happens intermittently several times a minute while observing any one star. I follow the up and right recommendation.

Fourth: I have used the scope about a dozen times and every night this exact problem happens several times and always to the right.

Fifth: Each night I have verified several times during a session that the balance doesnt need to be adjusted.

Sixth: I have done the balance and alignment by myself, with my son, and him alone. He also sees all of these exact same problems.

Seventh: The one motor has the same nice constant hum one expects from a high quality motor. The other motor has never sounded like that. The pitch of the sound goes up and down as if it were experiencing a significantly variable load. The last time I used it the motor was moving slower and slower. It was like I was running it off of a battery that was running out of charge but I always use my power supply.

I have done all of these steps several times each night. If there is a user error that explains all of these problems, then I want to hear it. The people at Orion are very nice and immediately ordered a replacement scope and I don't want to repeat it again on the new one.

#23 jrcrilly

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Posted 06 September 2013 - 02:04 PM

I can use the HC to move the scope in all 4 directions very smoothly. Then it stops responding to the right arrow button. I can push it multiple times or hold it down. After 1-3 seconds it suddenly slews at high speed in that direction like I had done a GOTO.


That's a symptom of an encoder problem.


The one motor has the same nice constant hum one expects from a high quality motor. The other motor has never sounded like that. The pitch of the sound goes up and down as if it were experiencing a significantly variable load.


That's a symptom of an encoder problem.

It is not user error. It's an encoder problem.

#24 Susan H

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Posted 09 September 2013 - 04:31 AM

Hi John, I know very little about encoders, my knowledge wouldn't fill a thimble. If it is an encoder problem, is it within the mount itself or the HC? I'm experiencing similar issues. But, I'm going to try a few things before I go back to where I purchased my AVX from. I want to insure it's not operator error. I'm going to do a 2 + 4 alignment and see how that does. If we have to do those kinds of alignments, then why are 1, 2, and 3 star alignments offered? I also make sure I have balanced my mount, done a very good polar alignment, and that it's level. I hate to think that I have to return this mount for a second time. First time the place where power is plugged in was bad. I'm hoping its the HC and that can be easily replaced. And I don't want to purchase a different mount all together.

#25 SunBlack

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Posted 09 September 2013 - 09:09 AM

UP.....

Some questions now:
1) What could be reason i had to correct frequently on DEC? ASPA inaccurate?
2) My Firmware versions are: HC: 5.22.3141 MC: 7.08.3071, should i upgrade something?
3) On Aligning and GOTOing, there's a feature that after pointing a star west to meridian, on going to a second star at east of meridian, i can avoid that the mount twists on itself, and goes to second star passing in front the meridian, doing "less road"? (my english is bad, i know)








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