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Equipment Discussions >> Mounts

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Whichwayisnorth
Pooh-Bah
*****

Reged: 07/04/11

Loc: Southern California
Re: Celestron VX mount [Re: Mkofski]
      #5633239 - 01/20/13 01:33 PM

Quote:

Michael,

I had a CG5 that did the same thing on the alignment stars. After the alignment was done everything was fine. I guess that everything was fine from the beginning and that was what the alignment stars were for.




Well my first night out with it which was Friday night the two first alignment stars were within reason, the first calibration star was very close and the second calibration star was very very very close. I went ahead and did two more because why not?

Last night was different. I set it all back up in a new spot, leveled the tripod, took both caps off the RA and sighted through them and tried to put Polaris kinda in the middle. Just to get a rough PA you understand.

I expect the first alignment star to be off because the mount doesn't have any reason to know where it is. But by the second I expect it to be in the ball park. It wasn't. After the second calibration start it was back to putting them near the center of the eyepiece. Once I did 2+4 I did a polar alignment using the built in routine. I then checked that by doing a quick drift alignment. Sad to say it wasn't very close after all. After fine tuning the drift alignment quite a bit, spending 30 minutes creating a pointing model using SkyX T-point and fighting with my OTA's collimation, focus etc, it was too late for me as I had to get up early. So hopefully tonight I can repeat this whole process a lot faster and have time to take some photos using my dslr with and without guiding. But I also have to get up early tomorrow so I have to do it fast and correct.


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Mkofski
Pooh-Bah
*****

Reged: 07/19/11

Loc: Greenfield, Indiana, USA
Re: Celestron VX mount [Re: Whichwayisnorth]
      #5633278 - 01/20/13 01:51 PM

Good luck tonight! Looking forward to your results. By the way, I enjoyed your videos. You had a good helper...

Although I'm a happy LX80 user at this point, I'm interested to see how the VX mount works out. It looks like everything that Meade did wrong on their introduction, Celestron did right. Delivery as soon a the announcement was made, a product that seems to work out of the box, etc. It may have not been a coincidence that the mount is currently only available from one dealer and that dealer is close to Celestron. In the event of a problem coping up, returning the mount wouldn't be a major issue. So far, you have to give credit to Celestron.

On the other side, the VX is more of an evolutionary product than the LX80 and I'd expect less problems initially.


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SkipW
sage


Reged: 02/03/11

Loc: Oklahoma, USA
Re: Celestron VX mount [Re: Mkofski]
      #5633380 - 01/20/13 02:56 PM

My CG5 would typically be fairly far off the pair of alignment stars (several degrees - maybe 10 or so), even with reasonably good initial polar alignment, accurate time (and TZ/DST setting) and location, but by the second cal star, it was usually very close. I discovered that if the second cal star wasn't near the center of the FOV, it was better to just cycle power and start over. Probably one of the earlier stars wasn't centered correctly; at any rate, if I kept going, GoTos were significantly less accurate than with a "good" 2+4 alignment and calibration.

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jwheel
professor emeritus


Reged: 01/23/08

Loc: Fort Davis TX
Re: Celestron VX mount [Re: SkipW]
      #5633421 - 01/20/13 03:27 PM

Looks like a nice mount.

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cherokawa
super member
*****

Reged: 10/19/08

Loc: Torrance, CA
Re: Celestron VX mount [Re: jwheel]
      #5633485 - 01/20/13 04:10 PM

Hi Michael,
I think a number of CGEM owners (amongst others) would be very interested in knowing how the "integer gear ratios" end up affecting PEC. Maybe you already have plans of doing this, but if you can use something like PEMPro to measure out-of-the-box PE and the improvement after PEC propramming, you'd be helping answer many of these questions. Thanks!!

PEMPro has a 60 day free trial - I used it last night to program my CGEM.


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cn register 5
scholastic sledgehammer


Reged: 12/26/12

Re: Celestron VX mount [Re: cherokawa]
      #5633811 - 01/20/13 07:26 PM

I used PECTool to program the PEC. It's a free download from the Celeston site.

PECTool may need updating to handle the AVX mount, at present it returns a message "Warning: Unknown Model type: 20". It's possible this will affect using PEMPro.

Chris


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orlyandico
Post Laureate
*****

Reged: 08/10/09

Loc: Singapore
Re: Celestron VX mount [Re: cn register 5]
      #5633877 - 01/20/13 08:19 PM

I think the first star being mis-aligned is due to inaccuracy of the index marks for home position.

I have the same issue with my CGEM - even with a very good polar alignment, when starting up from power off, the first star is usually quite a ways off, but the second one is pretty close to the center of the finder FOV and the succeeding ones are very close to the center of the main scope FOV.


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Orionis91
sage
*****

Reged: 03/01/10

Loc: Maryland USA
Re: Celestron VX mount [Re: orlyandico]
      #5633999 - 01/20/13 09:58 PM

My CG-5 is dead on my targets with a 2+4 alignment.

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David PavlichAdministrator
Transmographied
*****

Reged: 05/18/05

Loc: Mandeville, LA USA
Re: Celestron VX mount [Re: Orionis91]
      #5634029 - 01/20/13 10:14 PM

Quote:

My CG-5 is dead on my targets with a 2+4 alignment.




Ayup! The CG5-GT is one of the best deals in the hobby. I use a 10" Meade R and there's three 11lb counterweights on it and it tracks well and the gotos are just fine.

David


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orlyandico
Post Laureate
*****

Reged: 08/10/09

Loc: Singapore
Re: Celestron VX mount [Re: David Pavlich]
      #5634088 - 01/20/13 10:45 PM

I had a funny thought.... I was wondering if a replacement motor board could be made (by the NexSXD folks) so that we could drive the AP motors with a Nexstar..

Thing is, the AP motors are totally separate from the motor controller (the GTO CP3) so if we knew the pinout of the AP motors it should be possible to do this.

So we'd get the ASPA and the really good GoTo alignment on an AP mount, in a totally non-destructive way (the worm phase for PEM would be lost though). The Nexstar is that good!


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dr.who
professor emeritus
*****

Reged: 01/05/12

Re: Celestron VX mount [Re: drksky]
      #5634173 - 01/20/13 11:47 PM

Quote:

Dang..Woodland Hills must have a direct line to Celestron. Every place else still shows them as Pre-Order.




Farah, the owner, is well known in the community and seems to be very wired in with the major manufacturers. I think it's because she has compromising photos of everyone! Just kidding.

I think it's because she is the kind of person that people just like. She is charming and friendly and really wants to do well by the customer which is what keeps me coming back there and she has a good reputation in the community.

As an example Scott Roberts the CEO of Explore Scientific took the time out of his schedule to fight Los Angeles West Side traffic to drive up to her shop from LAX during his layover on the way to China just to stop by and socialize. Anyone who knows West Side Los Angeles traffic knows what a big deal this is!

Because of that I think she gets first crack at quite a bit of the new kit coming out...


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AlienRatDog
Carpal Tunnel
*****

Reged: 07/15/05

Loc: Ann Arbor
Re: Celestron VX mount [Re: dr.who]
      #5634605 - 01/21/13 09:55 AM

Is the new VX mount any quieter??

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dr.who
professor emeritus
*****

Reged: 01/05/12

Re: Celestron VX mount [Re: AlienRatDog]
      #5634918 - 01/21/13 12:57 PM

Much quieter! I had my CG5 and the VX out last night for a comparison I was doing between an 8" Edge HD and my 127mm APO. My CG5 sounds like two cat's having adult relations with each other. My CGEM sounded like it was loudly purring. The VX sounds like it's a smaller version of the purr that the CGEM makes. From what I have found with this mount it is what I would call a CGEM Lite.

Brass tacks it's a lot smoother motion sound and about 1/2 the level of the CG5.

Edited by dr.who (01/21/13 12:58 PM)


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cn register 5
scholastic sledgehammer


Reged: 12/26/12

Re: Celestron VX mount [Re: dr.who]
      #5635180 - 01/21/13 03:13 PM

Just so you know, the AVX has a 144 tooth gear so the worm period is 598.362 seconds.

PECTool handles this with no problem, PEMPro may need a bit of juggling to set the right period. I've let Ray know so.

Chris


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Whichwayisnorth
Pooh-Bah
*****

Reged: 07/04/11

Loc: Southern California
Re: Celestron VX mount [Re: cn register 5]
      #5635273 - 01/21/13 04:10 PM

Have you had any luck with Nexremote?

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cn register 5
scholastic sledgehammer


Reged: 12/26/12

Re: Celestron VX mount [Re: Whichwayisnorth]
      #5635340 - 01/21/13 04:54 PM

NexRemote works but thinks the mount is a CG5. I didn't spend a lot of time but it did align.

Chris


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davenport
newbie


Reged: 01/14/13

Re: Celestron VX mount [Re: dr.who]
      #5635704 - 01/21/13 08:59 PM

Greetings everyone,
Normally I prefer to lurk. But on the bearings issue I just had to set up an account to say something - mostly because I want to refocus the discussion.

Some of you guys are looking at it all backwards. You don't ask yourself "are there bearings" and then from that decided whether or not the mount will perform as you need. Instead you ask whether or not the mount will perform and from that decide whether the price meets that performance spec. Only if the mount fails that performance spec do you then go in and say "would the problem be fixed by adding bearings".

On top of that, a few of the things mentioned in this thread with regards to why you might want (or even require) bearings are completely unrelated. Since I went to the trouble to abandon lurker-dom, I might as well correct those while I am at it.


I saw someone early in this thread saying that they wanted improved PEC.
PEC doesn't work on Dec (at least not on Celestron mounts). Adding bearings to the Dec axis (if indeed they are missing) won't help your PEC (in RA).

Someone talked about "non-smooth" movement in Dec (I can't remember the words he used for "non-smooth".) And they were concerned that this non-smoothness would affect imaging.
Assuming you are polar aligned, DEC doesn't even turn when you are tracking the star - so a lack of perfect "smoothness" is irrelevant for tracking/imaging. (see however, the next item)

The lack of bearings could cause sticking which could lead to problems guiding in Dec.
The Dec axes of the CGEpro and CGEM have bearings and they also have issues guiding in Dec. Clearly, bearings alone are not sufficient to provide good Dec guiding. For that, you need a change to the motor controller firmware/electronics. There is a firmware fix in the works for CGEpro and CGEM. The Advanced VX is said to already have that firmware update! Until someone shows me that the Dec guiding problem present in other Celestron EQ mounts has "jumped the gap" to the AVX (which has new motors, new electronics, and presumably new firmware) I am inclined to give the Celestron engineers efforts the benefit of the doubt. I can understand why buyers will want to wait until others can independently verify this. Hopefully we will see some "guide" results soon.

The unit might wear out if dust got between the sliding surfaces (if there is no bearing).
As a rule I avoid pouring dirt in my mount. No really, I almost never do that. If that isn't possible for you, a good cleaning might be in order once a while. If such wear got really bad, then it might increase the noise from the mount, and it might affect pointing. But it wouldn't affect tracking/imaging unless it got so ridiculously bad that the whole thing was loose. I have never heard of such a thing actually happening. On the other hand I _have_ heard of cases where bearings in telescopes were too soft and so got warped/worn over time (which did screw up tracking in RA). And I have personally used seen bearings (they didn't happen to be in a telescope but a similar appliance) that caused the need for maintenance because the bearings were too hard.


Bearings can be replaced if they wear out, but a worn out slip surface spells the end of the entire mount.
Okay that is pretty much true. I think the motors or the gears would wear out before the slip surface, but suppose the slip surface really was the part that wears out first. How long would it take for that to occur? Should Celestron really design an $800 mount to last forever? I just bought a new cellular phone that cost me almost as much; and it will probably be hopelessly obsolete in less than 3 years. Unless you are tinkering with your mount, I can pretty much guarantee you that your mount will last a lot longer than 3 years.

None of this is to "justify" the failure to include bearings in the Dec axis, if indeed there are none. I am not an ME so I am in position to judge the whether or not this was a mistake. Instead, if this rant had a point at all, it would be that

"The lack of bearings on the DEC axis does not appear to present large problems for the design of a telescope of this caliber. There are much more important things people should be asking about this mount."

What things you ask? Off the top of my head I can think of several?

1. Has the Dec guiding issue really been resolved on this mount?
2. What is the typical hub error?
3. How stiff is this mount?
4. Does it have any vibration resonances?
5. If it binds when it is cold, can I easily adjust this in the field?
6. Will the all new firmware/electronics be compatible with my other hardware/software?
7. What is the raw pointing accuracy?
8. Will a "precise goto" ensure my object in the FoV of my camera?
9. What is the best guiding accuracy that I can expect to achieve?
10. What type of wind gust will the AVX tolerate before imaging is affected?
11. Will my polar alignment degrade if I brush the tripod leg with my sleeve?

Want to see something amazing? NONE of those questions can be answered by the knowledge of whether or not there bearings in the DEC axis. Only if it fails one of those criteria will I ask myself, someone pointlessly, whether or not Celestron could have done it better (at slightly higher cost of cousre) if they had included bearings in the DEC axis.

Until these other questions are answered, I might indeed be reluctant to buy this mount for my own imaging apparatus. And until these other questions are answered, the implementation details of the Dec Axis are of secondary concern (to me).

Dave


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rockethead26
Carpal Tunnel
*****

Reged: 10/21/09

Loc: Arizona, USA
Re: Celestron VX mount [Re: davenport]
      #5635719 - 01/21/13 09:07 PM

Dave,

Thanks for the clarification, it was really well stated. Oh yeah, welcome to CN, too.


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FoxTrot
sage


Reged: 06/01/06

Loc: Melbourne, Australia
Re: Celestron VX mount [Re: rockethead26]
      #5636187 - 01/22/13 03:27 AM

Mike, DrWho, see my previous post, but may I ask - do you think the VX's stiffness and load carrying capacity is cut above the old CG5 ? Also, whilst I wouldn't expect you to have pulled the motors apart (... yet), would you say the motor housing and their attachment is better than the LXD75? Thanks, Fox!

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Adam Taylor
insignificant bystander
*****

Reged: 11/11/10

Loc: Arizona
Re: Celestron VX mount [Re: cn register 5]
      #5636647 - 01/22/13 11:02 AM

Can the VX take a 3" Losmandy type dovetail? If not, can the saddle be changed for one that can?

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