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Dealing with RA Tracking Problems

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#1 StarWars

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Posted 04 October 2004 - 11:42 AM



Dealing with RA Tracking Problems.

http://home.att.net/...essin/etxra.htm

#2 seeker372011

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Posted 10 October 2004 - 10:08 PM

The link to the Microstar drive corrector page doesnt seem to be working?

#3 StarWars

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Posted 11 October 2004 - 11:00 AM

The link to the Microstar drive corrector page doesnt seem to be working?



Here is another link to the Microstar drive corrector page ..


http://www.weasner.c...microstar1.html

#4 Guest_**DONOTDELETE**_*

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Posted 12 October 2004 - 12:19 PM

I think the existence of this thread might answer my question, but...

I've been struggling over the course of several nights to get my ETX-125EC to track correctly for long-exposure photography. The tracking error seems to be in only one axis, namely, RA. Unfortunately, adjusting the tracking speed with the controller still doesn't create very satisfying results.

Now, I've been spoilt by using professional astro facilities for photography before I got my personal scope, and wanted to see if anyone else had problems with the ETX models having less-than-precise clock drives, or if I was just being picky.

#5 StarWars

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Posted 13 October 2004 - 02:09 AM



Supercharge the ETX-125 ..


http://www.arksky.org/supercharge.htm

#6 Rainbow

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Posted 23 April 2005 - 12:53 PM

The etx series is not designed for long exposure photography - instead you need to take lots of short shots and use image stacking software.

#7 rogerandgarf

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Posted 12 August 2005 - 12:43 AM

Remember that the autostar has a high-precision setting for tracking,etc.

#8 JAT Observatory

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Posted 12 August 2005 - 10:03 PM

The high-precision in the Autostar is not for tracking. It is used to make goto's more accurate by forcing you to align and sync on a bright star near the object you are slewing to.

#9 tom r.

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Posted 24 August 2006 - 02:03 PM

just returned my etx-125 to meade throught their Sky Assurance program. i have had this scope for over a year and a half when tracking and slewing problems started. it has not been a real pleasure dealing with meade. having to wait on hold for an average of about 45 minutes, once as long as an hour and 10 minutes, to get to a service support technician is poor service, IMHO.
tracking was jerky as the object would drift out from the center of view and then snap back to the center with a clicking noise eminating from the drive base. time will only tell how long their turn-around will be in returning the etx. after i receive the etx i plan on sending it our for supercharging and really start enjoying the precision tracking that this scope is capable of.
knowing what i know about meade's after sales support, i will be going elsewhere for that next upgrade (subliminal message ORION).
i think meade should heed my read and others should follow up with either their satisfaction, or dissatisfaction, with meade support.

#10 StarWars

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Posted 18 November 2007 - 07:44 PM




I think the supercharging involves replace factory gear Lubricant with a quality Lithium Lubricant plus optical adjustments.. :cool:

#11 NoiseJammer

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Posted 27 February 2008 - 08:12 PM

I've stripped my ETX105 several times in an attempt to improve the pointing and tracking. The components are identical. The short version is that unless you plan to confine yourself to shallow space, you probably need to mount the optics on a new mount, and even then it will be hard work.

The drive problem arises from two places... the basic drive mechanism and the time it takes the scope to respond to guiding corrections.

The first problem is (I think) dominated by the worm wheel which is about 38mm diameter - this is way too small to achieve ~2 arcsec tracking which you need for open loop imaging. It's also possible that the gearbox introduces a lot of periodic error - but there is no mechanism for correcting this.

The second problem relates to the control bandwidth. This might be specific to my scope (or how it's set up) but I can't get the delay down to less than several seconds. This is generally not going to help correcting your drive.

A final observation might be useful - you can gain a lot against drive problems by using a focal length reducer. Depending on your chip size, reducing to f/5 _may_ be possible, and f/10 probably is. This will reduce the exposure (9x at f/5, 2x at f/10.)

Clearest
Bruce, Toronto

Modified LX200/12, FLT110, ETX105

#12 Donnie D

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Posted 28 November 2009 - 04:30 PM

I hope you all don't mind me putting in my 2 cents. But, I have a DS2114. The Altitude adjustment has a small 3 prong cheap soft metal device that assist in making sure the OTA is secure. I have had this scope only for about a month and already, this piece is nearly stripped out due to the cheap metal. I guess plastic is fine for some things, but in reality, for telescopes, please put the plastic somewhere else. I would be willing to pay for the extra workmanship and parts, rather than dealing with a worn out scope in a few months.
Ok, next. The way they MEADE, that is, has the bottom RA motors and such is really like a TOY in the DS2114. It is so very imprecise, it is amazing that it works like it does.
I was very shocked as I opened up the AZ motor section.
I am having the same problem with once the star or object is in the eyepiece, all of a sudden the thing takes off. YES, it DOES have to do with the center bolt on mine. I am SURE that there is a TORQUE setting for this bolt. Too tight and you will have problems with the tracking-jerking-taking off by itself. But, it is what it is. This was bought at SAM's Club for under $300. So for a scope just to start out with learning the sky, I guess it is not too bad. THE OTA is fine. It is the drive mechanism that is like a TOY.

Donnie

#13 Joe Lalumia

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Posted 28 November 2009 - 04:52 PM

You CANNOT do long term sky tracking with a stock ETX. This is a fool's errand. Not trying to be harsh but it's just not made to do this. It's fine for visual or for SHORT say 8-20 second exposures stacked using various software.

If you search around for "Nytecam" he has taken some exceptional ETX astro-photos. I believe he now has it mounted on his LX200 telescope.

Clear Skies!

#14 Donnie D

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Posted 28 November 2009 - 11:07 PM

I am very sorry - I feel like I have taken away from what this post was all about. The one thing I want to do is make friends here and not run people off with my misunderstanding of things. I was able to repair my DS2114. It seems well now.
thanks goodness.
Donnie

#15 Ion01

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Posted 10 March 2010 - 11:40 AM

You CANNOT do long term sky tracking with a stock ETX. This is a fool's errand. Not trying to be harsh but it's just not made to do this. It's fine for visual or for SHORT say 8-20 second exposures stacked using various software.

If you search around for "Nytecam" he has taken some exceptional ETX astro-photos. I believe he now has it mounted on his LX200 telescope.

Clear Skies!


I have gotten consistent 30second images using the ETX and imaging with a 300mm camera piggybacked. I have also gotten enough 27 second images with the DSI pro II and the meade focal reducer with extention tube to get a great image of orion See Thread Here
I have also gotten some 30 second images without the extention tube attached. I noticed that in about 1 of 4 or 5 images there is some tracking error causing blurring of stars so far. I have taken a couple of exposures at 45 seconds and both had no trailing so you really have to be patient as the gears have to be in the right spot for them to turn out good. Also, having the camera track and make corrections is something I haven't gotten to work well yet as the scope is really slow to react to corrections. Does anyone have any "predictions" on how long an exposure can be taken and if proper guiding can be done with a supercharged scope?

#16 mikeslater

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Posted 21 November 2010 - 10:54 PM

I know this thread is kinda old but my etx is doing the same thing, is this a design flaw. It tracks for about 5 seconds and the snaps back into center. Only seems to be on the ra axis.

#17 lx200sct/IN

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Posted 29 March 2012 - 01:02 PM

I replaced the teflon bushing with a thrust needle roller bearing part numer (kit 8675)from VXB.com the size for my etx125 required a 35x52x4 mm bearing. The cost whith shipping was less than $10. I also relpaced all the grease with lithium grease and adjusted the worm gears to remove the backlash. You would not believe the difference in the scope for less than $20. It looks like Meade would have made the same in building. But, no repair work! No need for techinal department! Anyone needing help let me know and I can help you. I cut the wires that run between the two motors on the bottom side to make it easier and soldered them after assembly. Much easier for assembly.
hope it helps. I can lock the RA with two fingers. When assembled, the scope spins from side to side with no slop and no vertical movement. Like I said, you will not belive the difference for just $20. "VXB.com"

#18 jgraham

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Posted 29 March 2012 - 02:41 PM

Hmmm, I couldn't find VBX.com. Sounds interesting!

#19 Stew57

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Posted 29 March 2012 - 03:03 PM

Did something similar to an etx80
http://www.weasner.c...earing_mod.html

Going to try and run pec and see what happens.

#20 lx200sct/IN

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Posted 29 March 2012 - 03:58 PM

Sorry, VXB.com

#21 lx200sct/IN

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Posted 30 March 2012 - 09:56 AM

I looked at that before, nothing is changed but the nylon bushing. Just change it to a metal needle roller thrust bearing and lithum grease. No play or slop in the RA or vertical action. Just smooth movemement. With the scope sitting upright, without the RA gears installed, just a small push with a finger and the scope would travel from side to side.

#22 tomatohead

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Posted 30 March 2012 - 01:41 PM

I'm interested in the RA mod with the VXB bearings. Please post some pictures. How old is your 125, does it have the aluminum inner forks?

#23 lx200sct/IN

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Posted 31 March 2012 - 10:33 AM

I don't know how to post pictures yet but my 125 is a 2005 model with aluminum forks. If you do the mod, I can give you some info and save you lots of time. If I can find info for posting pictures I will post. Also, can exchange email and pass info faster.

#24 lx200sct/IN

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Posted 31 March 2012 - 01:04 PM

I have the pictures posted of my parts on mikes mighty ext site. I replaced the white nylon bushing with the thrust needle bearing from vxb. You can see the purple nylon stop piece that fits around the new bearing. This will correct RA slop in the scope.






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