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Jerky Movement in Mount -- Send it Back?

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#1 js10

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Posted 14 April 2021 - 06:03 PM

I'm having an issue with my 8" Celestron Evolution that I guess is turning out to be a lot harder to deal with than I thought. Basically, the situation is that I will slew to a target and get close, and then essentially need to slew at a slow speed in order to properly center it. However, quite often when I do so, rather than a smooth movement, the scope, and therefore what I'm seeing on my laptop screen (this is usually when I'm trying to do astrophotgraphy) will suddenly "jerk" -- it will basically fly off in one direction off my screen thereby forcing me to try to find it again and then make another attempt at centering it. I called the company I purchased it from and one of their support reps informed me that other people have reported this type of behavior with the Evolution specifically before, and said that it could be a problem in the gears themselves. 

 

He then passed my question on to Celestron itself, and the guy who responded also said it sounded like it could be a problem in the gears. He then (a few weeks later, actually) did issue me an RMA for it, which probably sounds like good news, but the problem is that due to issues involving the pandemic and closures in California, they are badly backlogged and could not provide an ETA oforwhen I would get it back! 

 

Quite frankly, I'm in NY and for a long time it was simply too cold to go out, so I was really looking forward to this time in which it is warming up and I can finally "step on the gas" a bit start making some progress (I'm still within my first year of this hobby!), so it would be devastating for me to have to give up the scope for an extended period of time now.  

 

Has anyone else here with the Evolution (or possibly a similar telescope) had this jerky movement problem? If so, did you send it back to them, and did that resolve the issue (I would REALLY hate to send it back to them, wait to have them send it back to me, and then STILL experience this problem!)? This one more a matter of opinion, but do you think it would be crazy of me to basically live with the problem for a while so that I can at least keep using it? The warranty, by the way, doesn't expire until just over a year from now, so that's not really an issue. Thank you. 



#2 MikiSJ

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Posted 14 April 2021 - 06:54 PM

Does the mount always 'jerk' in the same direction? Does the mount 'jerk' regardless of RA/DEC position?

 

Can you check the gears for any contamination?

 

Small movements during a centering of an object might be a backlash issue.

 

Celestron is fairly good at customer service (my belief). I would try to communicate with the individual who issued the RMA and see if it would be possible to have a mount set aside for a reasonable amount of time for you to sent your mount back to Torrance.



#3 Bean614

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Posted 14 April 2021 - 07:00 PM

What happened when you tried adjusting the backlash compensation? 


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#4 js10

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Posted 14 April 2021 - 08:37 PM

Small movements during a centering of an object might be a backlash issue.

Well, again, I'm a newbie at this, and have a vague idea of what backlash is, but that's about it. Unless this IS, in fact, backlash, in which case I guess I know by experiencing it! I do know that the Evolution is SUPPOSED to be backlash-resistant, which doesn't mean it always is. But I guess my question is how, if at all, that changes anything? I mean, if damage to the gears is causing excessive backlash, that's still damage to the gears, right? Unless, there is, in fact, a way to reasonably easily fix such an issue. Please see my next post for that.

 

To quickly answer your other questions, good question about the direction. I would have to try it again to answer definitively, but I MAY remember more instances in which it the object jumps up off my screen, which I guess would mean that the OTA jerks down. As for checking the gears for contamination, no, but is that really something a novice could possibly do? I'm still learning how to use the thing! And, lastly, what do you mean by a mount set aside? 

 

Thank you!

 

PS. One more quick thought. I thought (again, not knowing much about it) that backlash was more like a delay in the movement than uneven movement. No?


Edited by js10, 14 April 2021 - 08:42 PM.


#5 js10

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Posted 14 April 2021 - 08:44 PM

What happened when you tried adjusting the backlash compensation? 

Well, as I said in my last post, I don't even fully understand what backlash is, so I would never have tried to do that because I didn't know such a thing existed! To truly state the obvious, if there's some setting I could adjust with the hand controller to prevent this from happening, that would be a lot better than having to send it back and miss out on this nicer astronomy weather indefinitely! So, if you could elaborate on that, that would be great. I will say, though, that as I said above, this telescope is already supposed to be backlash-resistant, so I would think that its default settings would already be correct in terms of backlash (and, one more time, not knowing anything about backlash compensation, I certainly didn't change any of the defaults myself because I didn't even know I could).  



#6 mlord

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Posted 14 April 2021 - 08:57 PM

It sounds like maybe someone has already set backlash compensation values.  Which will then produce/explain some types of "jerky movements".

 

Just go into the menus on the hand-controller, or in SkyPortal or CPWI, and see if the backlash compensation settings are zero (defaults) or not.


Edited by mlord, 14 April 2021 - 09:03 PM.


#7 js10

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Posted 14 April 2021 - 09:35 PM

It sounds like maybe someone has already set backlash compensation values.  Which will then produce/explain some types of "jerky movements".

 

Just go into the menus on the hand-controller, or in SkyPortal or CPWI, and see if the backlash compensation settings are zero (defaults) or not.

Okay, interesting. I just went into SkyPortal, and I'm guessing that this setting is under "Setup and Control." If so, I get the "You must be connected to your scope to view or change its settings," which I can't do tonight, but will try tomorrow. Still, no one else has had access to it, so the only person it could have been was me, and, again, there is no reason I would have changed the default setting, as I never do so unless I know for sure what I'm doing (as in someone with expertise tells me to). Thank you. 



#8 Bean614

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Posted 14 April 2021 - 10:29 PM

Your Owner's Manual will show you how to adjust the settings.  The Manual SHOULD be read completely before ever using your scope.

And, always use the Hand Controller to adjust settings!!



#9 Maritime

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Posted 14 April 2021 - 10:31 PM

Good points. Op, keep in that changes made with the hand control are saved there, and the same is true of SkyPortal. Never do they meet, so make meaningful changes in the hand control.



#10 mlord

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Posted 14 April 2021 - 11:13 PM

The backlash settings can be adjusted either with SkyPortal or with the hand-controller.  They are stored at the mount, and both (SkyPortal, HC) fetch/store them in the same place.



#11 jasonjeremiah

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Posted 15 April 2021 - 12:26 AM

This might be a basic response, but I didn't read anywhere as to if you have the latest MC firmware installed.  I do remember there being a "jerky" or more of what I would call a hopping issue, when approaching a target at slow speeds, often after button is released.  Not sure which Nexstar's this effected, but it did effect a previous Nexstar I owned.  A firmware update fixed it.  May not be your issue at all, but never hurts to put it out there.



#12 Bean614

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Posted 15 April 2021 - 04:28 AM

This is an Excellent 'Teaching' thread!  It shows what can Really happen when the Owner's Manual is NOT read!  In many instances, by the time the Equipment Owner/Operator comes to CN, the damage is already done!

  Now, I'm not trying to make the OP feel bad here, but this thread has many classic lines.

The OP said:    "I do know that the Evolution is SUPPOSED to be backlash-resistant,"

 

                          Really????  Where does the manual say that?

                       -----------------------------------------------------------------------------

"I don't even fully understand what backlash is,"

 

Well, the Manual would have told you!

                        -----------------------------------------------------------------

"if there's some setting I could adjust with the hand controller to prevent this from happening, that would be a lot better than having to send it back and miss out on this nicer astronomy weather indefinitely"

 

Again, the Manual WOULD have told you what to do, and how to do it!

 

                                -------------------------------------------------------

"I would REALLY hate to send it back to them, wait to have them send it back to me, and then STILL experience this problem!"

 

    Well, unfortunately, this IS often the end result when an owner dives head-first into using an electronic/geared product (Audio/Video Gear, Cars, etc., are the SAME!) without first reading the Manual/Instructions!  The damage gets done.  Then the remorse sets in.


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#13 jasonjeremiah

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Posted 15 April 2021 - 07:28 AM

This is an Excellent 'Teaching' thread!  It shows what can Really happen when the Owner's Manual is NOT read!  In many instances, by the time the Equipment Owner/Operator comes to CN, the damage is already done!

  Now, I'm not trying to make the OP feel bad here, but this thread has many classic lines.

The OP said:    "I do know that the Evolution is SUPPOSED to be backlash-resistant,"

 

                          Really????  Where does the manual say that?

                       -----------------------------------------------------------------------------

"I don't even fully understand what backlash is,"

 

Well, the Manual would have told you!

                        -----------------------------------------------------------------

"if there's some setting I could adjust with the hand controller to prevent this from happening, that would be a lot better than having to send it back and miss out on this nicer astronomy weather indefinitely"

 

Again, the Manual WOULD have told you what to do, and how to do it!

 

                                -------------------------------------------------------

"I would REALLY hate to send it back to them, wait to have them send it back to me, and then STILL experience this problem!"

 

    Well, unfortunately, this IS often the end result when an owner dives head-first into using an electronic/geared product (Audio/Video Gear, Cars, etc., are the SAME!) without first reading the Manual/Instructions!  The damage gets done.  Then the remorse sets in.

Maybe the Celestron tech support guy should read the manual, too, as he issued an RMA to return the mount to them for repair.  You should get in some really good 'teaching' moments and contact the corporate office at Celestron and suggest their TSRs "read the manual" as they're obviously having people send in fully functioning and operating equipment for issues addressed in the manual.  


Edited by jasonjeremiah, 15 April 2021 - 07:35 AM.

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#14 Bean614

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Posted 15 April 2021 - 09:35 AM

Maybe the Celestron tech support guy should read the manual, too, as he issued an RMA to return the mount to them for repair.  You should get in some really good 'teaching' moments and contact the corporate office at Celestron and suggest their TSRs "read the manual" as they're obviously having people send in fully functioning and operating equipment for issues addressed in the manual.  

I have contacted them, (Been a customer for many years) and have gotten excellent help when I've had an issue.  However, they DO admit that they 'assume' some things about the scope owner (and Celestron knows this is an easy way to NOT help folks), one being that they've read the manual.  They should NOT simply 'assume' this, and ask the owner LOTS of questions to ascertain what the owner has done as far as making adjustments, changing settings, etc.



#15 mmcintosh1

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Posted 15 April 2021 - 12:36 PM

I sent my evolution mount in for repair last summer and got it back in about 5 weeks, including shipping time. I think if you send it in now, before everyone breaks out the gear for the season, it should be faster. 



#16 js10

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Posted 15 April 2021 - 01:28 PM

This is an Excellent 'Teaching' thread!  It shows what can Really happen when the Owner's Manual is NOT read!  In many instances, by the time the Equipment Owner/Operator comes to CN, the damage is already done!

  Now, I'm not trying to make the OP feel bad here, but this thread has many classic lines.

The OP said:    "I do know that the Evolution is SUPPOSED to be backlash-resistant,"

 

                          Really????  Where does the manual say that?

                       -----------------------------------------------------------------------------

From the High Point Scientific page marketing this telescope: "The computerized Evolution GoTo mount includes high-performance worm gears and motors for improved tracking accuracy, along with reduced gear backlash." Granted, it says "reduced" and not "eliminated," but that's why I wrote "resistant" and not "proof." Also the guy I spoke to at High Point mentioned this issue as one of the "pro's" of this telescope. The point is, I'm not trying to make you feel bad, either, but I have to say I do not appreciate you insinuating that I did not do my research on this purchase, because I most certainly did. 

 

Really, what I regret far more than anything involving the instruction manual is not hearing about and then purchasing the Mike Swanson book on Celestron telescopes, which I just happened to stumble upon in another thread here within the past few days. Quite frankly, if the instruction manual were that great, there would be no need for such a book. In fact, at least on Amazon, one common theme in the reviews is that Celestron's instruction manual leaves a lot to be desired, and that an independently-written book such as this makes things far clearer. 

 

Regarding backlash, specifically, if the telescope I purchased is supposed to have "reduced gear backlash," and I read about it in the instruction manual, I don't really feel any compunction for thinking that the settings should be correct right out of the box. When you're new to this hobby, having to adjust settings for backlash is something that just isn't going to resonate, and nothing in their instruction manual changes that (which is, again, why I wish I had known about that other book much earlier, as maybe then it would have). To me, this is a great example of the old adage "hindsight is 20/20." 

 

All right, I'm done now. Back to trying to FIX the problem, hopefully! 



#17 Bean614

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Posted 15 April 2021 - 02:18 PM

Sorry you felt insulted, as that certainly wasn't my intention!  I take info I read from a dealer with a 'grain of salt', same as the 'fluff' used by dealers to sell cars.  Additionally, having to adjust backlash in no way constitutes not 'working right out of the box'.  Every Scope/Mount is different, and things like focusers, gears, finders, WiFi connections, etc. usually need, as per the Manual, adjustment by the user to get them 'just right'.  Mike Swanson's book IS excellent, and I have both of them.  But the Manual, though ambiguous in spots, comes straight from the manufacturer (True with Any type of product, from Any manufacturer).  And if a particular feature isn't mentioned by the manufacturer, I don't pay attention to those who are trying to tell me what it SHOULD do.    

   Many folks on CN have, and are enjoying their Evo's, and after reading the Manual (even before the scope gets delivered) and everything else they can get their hands on before setting it up, they then come onto this forum for explanations of things they don't understand.  And they get Lots of help, as you're getting now!

   So, this is no reason to leave the hobby.  Double check the manual for 'best practices' in setting up for Alignment & Tracking, eliminating backlash (yes, as you point out, there's a difference---a big one--- between 'eliminates' and 'reduces', since 'reduces' indicates there Will be backlash), pointing accuracy, etc.  I'm sure you'll do fine in the end! Good Luck!



#18 js10

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Posted 15 April 2021 - 03:50 PM

Okay, well, I appreciate that. Not that I want to go too far into the weeds with this, but copying and pasting the exact part of the manual pertaining to backlash:

 

All mechanical gears have a certain amount of backlash or
play between the gears

 

. This is seen as a delay in the time
it takes for the telescope to move after a direction arrow is
pressed, especially when changing directions

 

. Anti-back lash compensates for backlash by inputting a value which
quickly rewinds the motors just enough to eliminate the play
between gears
.
• Altitude - Sets the backlash compensation value for alti
tude (up/down motion of the telescope), 0-99
.
• Azimuth - Sets the backlash compensation value for azi
muth (left/right motion of the telescope), 0-99
 

Again, maybe from your perspective as a more experienced astronomer, this is a clear warning. But to me this is a far cry from "don't use telescope without first adjusting these settings or you will risk damaging the gears!" If that's the case, they should say so explicitly, and maybe that's where the Swanson book comes in -- I don't know. I do know that one of its topic is supposed to be proper cleaning and maintenance. The point is, I probably DID read that and thought little if not nothing of it. Plus, reading that explanation makes me wonder if backlash truly is even the problem, as a delay in movement is not, to me, the same as uneven movement. 

 

At any rate, I have no intention of leaving the hobby! At all! That's the point. I want to make progress, and you can read all you want, but the only way to really progress is by doing, and that can't happen if I'm without it for an extended amount of time right after being forced to take a break for winter. 


Edited by js10, 15 April 2021 - 04:20 PM.

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#19 js10

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Posted 17 April 2021 - 03:25 PM

Just go into the menus on the hand-controller, or in SkyPortal or CPWI, and see if the backlash compensation settings are zero (defaults) or not.

Okay, so I finally got this done this afternoon. The result is pretty much as I expected. In the "Anti-Backlash" setting, both Az and Alt are set to zero, with circle placed at the very left-hand side of the slider. Which sounds like it's the default. So does this imply that backlash compensation is NOT the problem and that there is just a problem with the gears that can only be fixed by them going in? 


Edited by js10, 17 April 2021 - 03:25 PM.


#20 mlord

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Posted 17 April 2021 - 03:39 PM

In the "Anti-Backlash" setting, both Az and Alt are set to zero ... does this imply that backlash compensation is NOT the problem and that there is just a problem with the gears that can only be fixed by them going in? 

Sounds like it, yes.



#21 js10

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Posted 17 April 2021 - 09:02 PM

Okay, interesting. I'll say one thing, then. For all the talk about reading the instruction manual so that my settings are such that I don't damage the gears, it sounds like that wasn't the issue, and that I therefore didn't do anything wrong! 



#22 mlord

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Posted 17 April 2021 - 09:06 PM

Pardon the question, but I like to operate with very few assumptions.  Is this a question of simply switching to a lower motor speed before the final centering of an object?



#23 js10

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Posted 17 April 2021 - 10:27 PM

Well, for sure, it only happens when slewing at low speeds (not when the telescope traverses much of the sky in order to find an object). But if what you are asking is, am I trying to make very fine movements while the slew speed is set to a high speed, no. Again, at that point, I chose the lower speed. So, the movement is slow, but it's uneven, which is the problem. One time when I start the movement, it will move as intended. The next, it will jump. 

 

Quick story: obviously outreach events are very restricted now (hopefully not for long), but last fall a family did come down to my astronomy club's viewing area and watched me as I tried get an image of Jupiter. It was on my laptop screen, and they were very impressed (especially the kids), and was trying to center it. And then it happened. I tried to make a joke out it, saying something like "oh no, I destroyed Jupiter!" (as that's almost what it looked like as it vanished from my screen), but I felt bad. Here I am trying to put on a little show an then I have to deal with that. The point is, yeah, this is real, whatever the cause. 



#24 Noah4x4

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Posted 18 April 2021 - 01:08 AM

The key statement for me is "usually when doing Astrophotography". Are you attempting this at f/10 with a small sensor, small FOV camera?

I recall exactly the same experience when I first got my Evolution. The solution is improve all your skills and learn how to manage your scope.

1. Update all of your firmware.
2. Accurately calibrate Starsense.
3. Add additional alignment points.
4 Adjust backlash (you can do this in daytime, aim at a distant chimney).
5. Use a much slower speed when slewing.

It took me a while to master everything. I recall Jupiter frustratingly flying past my view and struggling to find where it had gone. Today, when imaging at f/6.3, my GoTos are generally spot on. But at f/10 (for planetary) it remains challenging.

#25 mlord

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Posted 18 April 2021 - 08:24 AM

From reading earlier posts, he has already done all of the relevant stuff from that list.  Dunno about #1, but it has no effect on slow manual slewing.




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