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CEM120EC2 - Looking for Help and Information

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#1 rgsalinger

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Posted 23 July 2019 - 03:05 PM

I've had a CEM120EC2 for about 15 months. Until Saturday I used it with my refractors - WO71, TV127is, and AP155. Guiding has always been excellent and stars have always looked fine in the raw images. I've had a second system out in New Mexico for almost a year with a Planewave CDK12.5 on it accompanied by a QHY16200A camera. In the interim, I've been renovating an old observatory about 90 miles from my house. That observatory is finally finished enough that I could bring back the NM system and have both of my imaging platforms in one place. 

 

The CEM!20EC2 has been in the renovated observatory for about 3 months now with my TV127is on it. I use a PierTech pier with it. The pad it sits on a 48" concrete cube (with rebar) with j-bolts connecting to a short rat cage arrangement using 3/4" in bolts and nuts. It's rock solid and is isolated from the rest of the observatory by a 1" border of packed earth.  I spent the late afternoon on Saturday setting it up the PW system on the pier. Since I was switching computers at the same time there was quite a bit of wiring and software that needed to be upgraded/changed. By about 9PM I was ready to go. Between 9 PM and 11PM I found a few more user errors (loose screw in my OAG) and cleared those up.

 

At that point I was confident that I was finished with the teething issues. I proved this by guiding for 15 minutes each with two different guiding programs. I calibrated each one at the meridian and slewed to an object. Results were perfect - .2 and .3 arc seconds of RMS using the SKYX. and  with MaximDL again got well under .5 seconds RMS in both axes. So, then I ran a 5 minute guided exposure. Every single star was elongated across the QHY16200A frame. I ran CCD Inspector and it reported that the collimation is essentially perfect and there is very little tilt. I then ran a short unguided exposure and I got the same egg shaped stars. The short exposure results meant that I could rule out an unstable pier. The CCDI results meant that I could rule out the camera or the optics. I was left with (a complete surprise) a mount problem. I then rotated the camera 90 and the elongation rotated with it  At both angles the elongation was precisely parallel to the RA axis. I then ran a bunch of guided/unguided exposure. They all showed exactly the same defect with the stars and it didn't increase with exposure time. 

 

I've fruitlessly exchanged emails and phone calls with iOptron over the past two days. They are unwilling to stipulate whether this is a problem with every one of these mounts or just for some of them (mine is one of the first). They have offered no useful advice to allow me to fix it myself. They are unwilling to take it back and fix it themselves or to give me a refund. So, I'm hoping that someone had this issue and somehow solved it. 

 

I'd like to hear from anyone who owns any CEM120 mount with or without encoders about whether they have the same problem or not. I'd like to ascertain if this is inherent in the design or (sigh) user error.

 

 



#2 OldManSky

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Posted 23 July 2019 - 03:28 PM

This may be a stupid question, but I'll ask it anyway:

Since you're getting the exact same results guided/unguided, are you sure guide pulses are getting to the mount?

You did change/rewire all sorts of stuff, so perhaps there's an issue with either the guide pulses not getting there, or a guide rate somehow got changed?

(I always try the easy solution first! :)



#3 dhaval

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Posted 23 July 2019 - 03:31 PM

Hey Ross, nothing to offer in the form of a solution from me, but I am a bit surprised that you are having this issue now. I know you have loved the mount excepting the first few times when you had to work with iOptron to fix driver/software related issues - could it just be the fact that you probably have some software glitch underneath? It would be bad if something physically broke in the mount when you moved it. I am also surprised that you have not had a decent response from iOptron, not sure if that can be put down to bad CS - I have heard that as sales have picked up, they have slacked a bit on the CS side. 

 

In any case, I hope you can turn this around quickly. 

 

CS! 



#4 rgsalinger

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Posted 23 July 2019 - 04:08 PM

Excellent questions both.

 

OMS---- While I did not put a voltmeter on the mount, I could see corrections being sent and made in the guide graphs using both software packages. MDL and the SKYX just connect to the iOptron Commander Driver - ascom guiding. Also, I did not change any of the wiring or install any new software (initially) for the mount. The same cable goes from the computer to the mount. The only relevant software/cabling change was to put in a different cable and driver to support the Lodestar X2 guide camera. (The previous system had a ZWO 290 mini guide camera which uses a USB C cable.) That's really all that I did.

 

DB --- I can't get a clear reading from iOptron. Some of this is due to a clear (sigh) language barrier. They seem to say that they know about the problem (so it must have been lurking for at least 15 months) but don't yet have a fix for it. It seems odd to me that a problem with guiding under "load" (their term) would take a competent developer 15 months to fix so I don't really know what to make of it. I asked a bunch of questions - can I turn off the encoders? what if I just guide infrequently? have others had the same problem? No answers from them that I can understand. I've had such good luck with them in the past that I am baffled.

 

I'm really hoping that someone else has the mount and has cured the issue. I configured my entire observatory to make this mount the centerpiece of my imaging. If it doesn't work properly it will be a huge job move the Paramount over.

 

Rgrds-Ross



#5 dr.who

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Posted 23 July 2019 - 04:37 PM

Another stupid question... Any chance of them telling you how to turn off the encoders? Or can you safely physically disconnect/disable them yourself and fool the mount into thinking it isn't the EC version? That will tell you if it is an encoder problem or a different part of the mount that could be the problem...

 

In short I am asking if you can do a major subsystem by major subsystem test. That way you can isolate the problem...

 

Edit: You had a voltage meter on the outside wiring so you saw the guide pulses, any way you can find out from iOptrion if there is a way to see what the mount is getting in terms of the commands being sent and interpreting them? The term for this escapes me at the moment but I want to say sniff the i/o bus to see what is going in and out...



#6 Chuckwagon

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Posted 23 July 2019 - 06:10 PM

Ok, let me make sure I have things straight in my mind.

 

- You have two CEM120EC2 mounts, one (formerly remote) with a Planewave CDK 12.5" on it, and one (local) with a Televue NP127Is, in addition to other scopes previously used on it.

- Previously, both setups worked fine without egg shaped stars.

- You are using the QHY16200A camera with the setup causing the issue.

- Whether you guide or not, the stars end up with the same egg shape.

- The egg shape is the same size regardless of exposure duration.

 

So, if that's all true, then we can surmise that;

 

- You are not having an RA drift issue, as that would make the shape larger with longer duration exposures.

- You are not having a PA error issue, as once again longer exposures would make larger stars.

- The problem is not time dependent, since the stars are the same size and shape regardless of exposure length.

- The problem is not seeing or refraction related, as once again time would affect those.

 

Therefore, my questions would be;

 

- What is your image scale?  I am unclear which telescope you were using, so I'm not sure of your image scale.  If it was the Televue NP127Is scope, then it has an image scale of ~1.87" per pixel.  If it was the Planewave CDK 12.5" then it has an image scale of ~.49" per pixel. 

- What was your guiding image scale when you tested and things looked excellent?

- Have you tried other scopes on the problem mount?

- Is your other mount showing the same issue now?

- How much elongation is there?  How many pixels out of round is each star?  (This will establish the magnitude of the deviation, and of course relies on the image scale.)

- What tracking rate are you using?  Have you tried changing it?

- You double checked that the firmware setting was correct for "Allow RA Guiding," right?  (At least that's how the manual lists it, I don't know if it's changed with some of the firmware updates.)  I know you didn't change it, but maybe it got reset somehow during the move.  Also, these are EC2 mounts, right?  So originally the firmware had a setting to filter guide commands for RA, but not for DEC.  Is that still true, or have they addressed that with a firmware update?  If so, I assume you turn off guiding for DEC so as to not waste CPU time calculating something that won't matter.  :)

 

I find it interesting that your guiding tests were excellent, but your actual images have an issue.  Maybe try doing your guiding test again but with your main scope.  Perhaps the issue didn't show up in your previous guide test because the guide image scale wasn't fine enough.

 

This seems an odd sort of issue, to go from functional to wacky just from being moved.  I hope you can track it down without too much hassle.



#7 dhaval

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Posted 23 July 2019 - 06:46 PM

Ok, let me make sure I have things straight in my mind.

 

- You have two CEM120EC2 mounts, one (formerly remote) with a Planewave CDK 12.5" on it, and one (local) with a Televue NP127Is, in addition to other scopes previously used on it.

 

Charles,

I believe Ross has only one CEM120EC2 mount, not two. He had it set up remote in NM and has now moved it back to CA.

 

What I am not clear about though is, how did Ross run his 15 minute guiding routine? 

 

CS! 



#8 rgsalinger

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Posted 23 July 2019 - 07:40 PM

1. I have asked iOptron how to turn off the encoders. This was met with silence, so I don't think that you can. They did recommend trying a "beta" firmware release but were unable (unwilling?) to document any success. To me this implied that they have known about the problem for a long time. That's speculation on my part.  I did call the head of sales at iOptron twice, left a detailed message about the problem, but didn't get a return call. 

 

2. Right now I have two mounts in my observatory. One is the CEM120 plus my PW 12.5. The other has a Paramount MX+ and a TV127is on it. The Paramount and the PW 12.5 were in New Mexico and I brought them back to my new observatory last Wednesday. Hope that clears that up. For all my tests the image scale was around .5 arc seconds. 

 

3. I wondered about RA drift as a culprit and so I set the RA to track fast and slow (and I also used the king rate) while taking 30 second shots. All that happened was that the stars drifted. This was easy to see in Maxim DL as I zoomed in on a single star and watched it move as each frame come in. The elongation value did not (appear to) change - measured around .3 in MaximDL where the standard for round stars is .1 (or maybe .12). This is not a subtle problem.

 

4. All of the stars showed exactly the same thing. The eccentricity gets a tiny bit worse at 5 minutes but not much - maybe to .35 or so from .3. For the images taken when guiding, the guiding was uniformly excellent and there was no wind. (I have my own weather station and I checked in real time.) 

 

5.  Not only did I check the RA Guiding Filter box but I turned it on and off with no change at short exposures. The mount is powered by the same exact power supply that was on it before I installed the Planewave. The camera and the Planewave focuser, fans and heaters are on a different power supply from the mount. So, I'm ruling out power as a cause. 

 

I think that what's happening is that there is a fixed amount of jitter in the mount's software coming from a battle between the motors and the encoders. This is essentially invisible at small image scales because it is only a fraction of an arc second - a tiny fraction of a pixel. When you get good seeing and more pixels per star it becomes bigger and bigger.

 

It's  hard to believe that a vendor would put something like this on the market for people to stumble over. That's why I am hoping to find someone else who had the problem and fixed it. I've also sent email to the store where I bought it but they have not replied either. It's all very odd to me. I'll be going out tomorrow and will run more tests. Suggestions are more than welcome but I think that the big telescope uncovered a problem that's been lurking in my mount since I got it. 

 

Rgrds-Ross



#9 Chuckwagon

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Posted 23 July 2019 - 08:39 PM

Ok, that clears things up.

 

You are using an OAG, so I don't understand how the guide software can't see the jitter.  What camera are you using for guiding?  Is it's scale much different from the main camera?  Maybe just use your main camera, no OAG, and see how it guides.  Try much longer or much shorter guide exposures to see if the jitter shows.  Also, if you have a sample of what the stars look like it'd be interesting to see.

 

P.S. - What guide software are you using?


Edited by Chuckwagon, 23 July 2019 - 08:39 PM.


#10 rgsalinger

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Posted 23 July 2019 - 08:43 PM

The guide camera is a Lodestar X2 which has 8.4 micron pixels. The stars are bigger in the guide camera as it's binned 2x2 which takes it to around 1.5 arc seconds per pixel. That's the same scale, more or less that I had with the Tv127is and the ASI1600 camera on that system. Here's a link to some of the images. You can check the FITS headers to see what the exposures were. These are just some that I saved and sent to iOptron hoping they would look at them. They didn't. 

 

https://drive.google...Nan?usp=sharing

 

Rgrds-Ross



#11 DuncanM

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Posted 23 July 2019 - 08:46 PM

I've had a CEM120EC2 for about 15 months. Until Saturday I used it with my refractors - WO71, TV127is, and AP155. Guiding has always been excellent and stars have always looked fine in the raw images. I've had a second system out in New Mexico for almost a year with a Planewave CDK12.5 on it accompanied by a QHY16200A camera. In the interim, I've been renovating an old observatory about 90 miles from my house. That observatory is finally finished enough that I could bring back the NM system and have both of my imaging platforms in one place. 

 

The CEM!20EC2 has been in the renovated observatory for about 3 months now with my TV127is on it. I use a PierTech pier with it. The pad it sits on a 48" concrete cube (with rebar) with j-bolts connecting to a short rat cage arrangement using 3/4" in bolts and nuts. It's rock solid and is isolated from the rest of the observatory by a 1" border of packed earth.  I spent the late afternoon on Saturday setting it up the PW system on the pier. Since I was switching computers at the same time there was quite a bit of wiring and software that needed to be upgraded/changed. By about 9PM I was ready to go. Between 9 PM and 11PM I found a few more user errors (loose screw in my OAG) and cleared those up.

 

At that point I was confident that I was finished with the teething issues. I proved this by guiding for 15 minutes each with two different guiding programs. I calibrated each one at the meridian and slewed to an object. Results were perfect - .2 and .3 arc seconds of RMS using the SKYX. and  with MaximDL again got well under .5 seconds RMS in both axes. So, then I ran a 5 minute guided exposure. Every single star was elongated across the QHY16200A frame. I ran CCD Inspector and it reported that the collimation is essentially perfect and there is very little tilt. I then ran a short unguided exposure and I got the same egg shaped stars. The short exposure results meant that I could rule out an unstable pier. The CCDI results meant that I could rule out the camera or the optics. I was left with (a complete surprise) a mount problem. I then rotated the camera 90 and the elongation rotated with it  At both angles the elongation was precisely parallel to the RA axis. I then ran a bunch of guided/unguided exposure. They all showed exactly the same defect with the stars and it didn't increase with exposure time. 

 

I've fruitlessly exchanged emails and phone calls with iOptron over the past two days. They are unwilling to stipulate whether this is a problem with every one of these mounts or just for some of them (mine is one of the first). They have offered no useful advice to allow me to fix it myself. They are unwilling to take it back and fix it themselves or to give me a refund. So, I'm hoping that someone had this issue and somehow solved it. 

 

I'd like to hear from anyone who owns any CEM120 mount with or without encoders about whether they have the same problem or not. I'd like to ascertain if this is inherent in the design or (sigh) user error.

My CEM120 seems to guide well and produce round stars at ~1750mm EFL (10in SCT @F6.9) using 5min subs. Longer subs are marred by primary mirror movement.

 

It might be worthwhile to deliberately misalign the mount in Azimuth by ~5 degrees, and then do some long unguided exposures which should produce star trails that will show if there's any recurring pattern in RA. Perfect RA tracking would show straightline star trails.

 

Edit: I used Astroart7 for guiding and it reported accurate guiding. My stars sizes grow with increasing  exposure per sub frame due to mirror movement.


Edited by DuncanM, 24 July 2019 - 05:48 PM.


#12 Chuckwagon

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Posted 23 July 2019 - 09:28 PM

From the image I looked at, the couple of stars I examined were smeared side to side from about 12-22 pixels total.  That'd be about 6-11" of motion.  That's enough I'm a bit surprised the guider doesn't see it, even at the lower 1.33" resolution of the X2 camera.  Maybe the jitter is either too fast or too slow for the guide exposure to "see."  I would definitely try to test auto-guiding again using the main camera, and adjust exposure times to see if you can bring out the jitter. 

 

And, just to hit all the bases and eliminate the optics as an issue, try your next longest focal length scope with whatever camera will give it the finest image scale.  See if the wacky stars remain.  As bad as those stars look, I'd bet a scale of 1" would still show it.

 

P.S. - The FITS header for the image I looked at said it was a 3 second image.  That's a lot of motion in a short time.  If that is correct, I'm shocked the guider doesn't see this issue.


Edited by Chuckwagon, 23 July 2019 - 09:34 PM.


#13 rgsalinger

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Posted 23 July 2019 - 10:03 PM

Duncan - can you tell me what firmware you are using and what the weight is of your system?

 

Chuck - please look at some of the other subs. I think you picked one that was prior to my running an auto focus session. 

 

Rgrds-Ross



#14 DuncanM

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Posted 23 July 2019 - 10:53 PM

Duncan - can you tell me what firmware you are using and what the weight is of your system?

 

Chuck - please look at some of the other subs. I think you picked one that was prior to my running an auto focus session. 

 

Rgrds-Ross

Total OTA and equipment weight is about 40lb. I'm using:

V20180206 Firmware for HC
V20180620 Mount firmware 



#15 rgsalinger

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Posted 23 July 2019 - 10:58 PM

Yes, sounds like weight is the issue. I was at around 40 pounds when I was using my AP155 and had no trouble. I'm thinking that I might pull the heavy camera off the system and go with my one shot color camera and see if 8 pounds less weight makes a difference. This is consistent with what iOptron appeared to be saying - that it was weight and not focal length. Makes on sense to me but they used the term "load". 

Rgrds-Ross



#16 DuncanM

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Posted 24 July 2019 - 12:08 AM

Yes, sounds like weight is the issue. I was at around 40 pounds when I was using my AP155 and had no trouble. I'm thinking that I might pull the heavy camera off the system and go with my one shot color camera and see if 8 pounds less weight makes a difference. This is consistent with what iOptron appeared to be saying - that it was weight and not focal length. Makes on sense to me but they used the term "load". 

Rgrds-Ross

I kinda doubt that 8 lbs will make a difference unless it created some kind of imbalance, or long lever arm that setup an oscillation.



#17 rgsalinger

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Posted 24 July 2019 - 12:20 AM

I have nothing to go on as the vendor basically just hand waves. I've now found some other folks who may have the same problem but that needs confirmation. If I get rid of the heavy camera I may also then not need to extra weight on the front of the OTA that I needed to balance the DEC axis. And that would save another 3 pounds. We'll just have to see. It would be great if iOptron would just give me some ideas to try out beyond a dubious beta firmware release.

Rgrds-Ross 



#18 Chuckwagon

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Posted 24 July 2019 - 02:18 AM

Chuck - please look at some of the other subs. I think you picked one that was prior to my running an auto focus session. 

 

Rgrds-Ross

Must have.  I download all of the files, and the issue is not nearly as severe with the other pics.  It's still pretty surprising though that 6, 10, and 20 second exposures show so much movement.  I'd estimate 6-8 pixels worth.  Almost like it's vibrating side to side.  The 300 second exposure (CCD Image 39) had better shaped stars than the 10 second shot.  Was that 300s one guided?  Maybe the focus wasn't as well done on the shorter shots.  I see that the star field is different for the 300 second shots, so maybe it had better focus.

 

I think your plan to try a different camera and see if the weight makes a difference is a good idea.  I'd also suggest a PHD2 Guiding Assistant run with just the main scope and camera to try to see if it can detect any issues.

 

Just as an aside, the 300 second image isn't horrible, bad, but not horrible.  :)  Siril indicates that the roundness of the 925 stars it detected is .851.  (1 is round in Siril.)  Over 60 of the stars were .94 or better.  By comparison, it only detects 47 stars in the 20 second image, and gives a roundness of .758.  None of the detected stars had a roundness over .81.  If I look at single stars of similar brightness, near the center of the field, the star from the 20s image has a roundness of .779 and the one from the 300s image is .844.  It's odd that the much longer image would have better roundness.  This is an odd issue indeed.



#19 Der_Pit

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Posted 24 July 2019 - 07:19 AM

I don't have a 120, but a 60EC, that also has encoder issues for some (most?) of its users.  So I wonder if it's related in some way.

 

But first another question:  Are you sure there's no (vibrating) fan around?  In the camera, or somewhere else?  That you get the eggs no matter what is disturbing.  And I remember one other thread about eggs that was cause by a fan with some imbalance....  IIRC they had used the acceleration sensors of a smartphone (and some app) to measure those vibrations.

 

That (as I understand) the mount had worked flawlessly before, and now gives issues makes me wonder if it is related to encoder calibration and/or zero position (not knowing the 120 I assume it's similar to the 60 in that respect).  Maybe it's worth re-doing those calibrations and make sure everything goes well and zero positions during encoder calibration and normal operation are the same.

 

Apart from that I'd run the guide software at fast rate (<<1s, without guiding), both with the guide cam and the main cam, and check what you get there.



#20 rgsalinger

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Posted 24 July 2019 - 08:03 AM

The Planewave fans were not running as the mirror had already cooled down. I can't turn off the QHY cooling fan as far as I know, but I doubt it's the problem. The ASI071 has a fan that I can turn off by just disconnecting it. That's what I'll do today and if I get clear skies tonight we'll see. I don't know what Siril is but MaximDL tells me that they are all unacceptable for further processing. I agree that the longer images are better. I think that's because the FWHM is worse which masks the problem. It's basically the same effect that the large image scale showed.

 

I plan to try the beta firmware tonight and see what that does. Then I will swap out the camera and see what that does. I changed the firme ware last time I was out and recalibrated the encoders at that time So, I've already taken care of the possibility that the calibration is off but I'll need to do it again with the new firmware. Then I'll use PHD for guiding and see what happens when I up the cadence. I did that a while back with one of my refractors on the mount and it was fine at a one second guiding cadence.  

 

After that I have no idea what to do next given that the mount doesn't work and the vendor won't even pick up the phone. Are they on vacation?

 

Rgrds-Ross



#21 denny-o

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Posted 24 July 2019 - 01:24 PM

While I suspect that you have done everything possible to pinpoint the cause of the image degradation, let me make a suggestion that might (long long shot) be an issue. Is it possible there is ground vibration at your new location? Perhaps a vibration sensor placed on the mount and look at the signal with the mount still and with it tracking in RA would be illuminating. My suspicion is that you will find it to be the mount - but hey, lightning strikes once in a while.

 

And let me say you have my sympathy. These sudden problems make one tear ones hair out. I hit a minor one (vastly minor compared to yours) 2 nights ago. First decent nite in weeks. I dragged the gear out and set up in the afternoon. Come dark, I clicked on PhD2 to start tracking a guide star and it insolently replies it can't find Com 6 (Win 10 of course) It hasn't mentioned this on prior nites (few and far between). There was no change to the cabling or anything else (to my knowledge) It was late, I was beat and I gave up (mutter mumble  &*%#@!  as I lugged things back inside)



#22 EFT

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Posted 24 July 2019 - 03:18 PM

I agree that is unlikely, but there are apps out there that do well enough for a quick vibration test so you may as well give it a try since they're free if you have an Android device.  They are also good for measuring damping times.



#23 WadeH237

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Posted 24 July 2019 - 03:38 PM

I then ran a short unguided exposure and I got the same egg shaped stars.

If the stars are the same shape, regardless of the length of the exposures, then it's not likely the mount at all.  To be completely sure, I would suggest pointing into an area rich with stars and then taking a very short exposure so that you can check the shapes.

 

One person able suggested a vibration, and this seems like a possibility to me.  There was a thread a year or so back where someone had your exact symptoms, except that it was intermittent.  Sometimes the stars were round and sometimes they were eggs.  It was independent of exposure length, and the optics were fine.  It turned out that he was imaging from his patio, and when the pump on his swimming pool cycled on, the vibration was causing the problem.  The thread went on for a long time, while he tried lots of things without success.

 

One thing that you can do to look for this kind of vibration is to slowly slew the mount in one axis while the camera is exposing.  If the star trails have tiny zig-zags, then the problem is almost certainly a vibration from somewhere.



#24 Chuckwagon

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Posted 24 July 2019 - 04:03 PM

One thing that you can do to look for this kind of vibration is to slowly slew the mount in one axis while the camera is exposing.  If the star trails have tiny zig-zags, then the problem is almost certainly a vibration from somewhere.

If it's an environmental vibration, could you just stop the motors, with the mount pointing near the celestial equator and meridian for best effect, and let the stars trail across the frame?  Then anything other than a straight line is not the mount's fault.

 

Also, for anyone wondering what the stars look like, here are two crops from the centers of a 60 second and 300 second exposure that Ross posted as fits files on his Google drive.  (In the thread above if you want full versions)  You can see how similar the shapes are.  The star fields are different, and I believe Ross rotated the camera for the longer shot so that's why the direction of elongation is different.  But the shapes sure are similar, in spite of the time difference.

Attached Thumbnails

  • 60 Sec Crop.png
  • 300 Sec Crop.png


#25 OzAndrewJ

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Posted 24 July 2019 - 04:14 PM

Gday Ross

 

Did the CDK normally run on the Paramount in NM ???

ie has the imaging scale on the 120EC reduced by swapping scopes??

If there was quite a difference in FL and you now have a small "egg shaped" error that doesnt get bigger with exposure length, it sounds like one of the things reported by early users of guided 60ECs,

We deduced back then that when the resolution of the main cam got smaller than the SDE, it started to show in images, and for people with bigger arcsec/pix "widefield" shots, it didnt show in the images.

Sooo, i agree with Der Pit here

Try and grab say 10-20 mins of unguided data using the longest focal length you can and the highest framerate you can get.

You really need to grab data at say 800ms or less to get best resolution.

If you see a ripple at about 3.33seconds period, then your encoder SDE might be peeking through.

If it is ground vibrations ( and they are steady ), it may show a different vibration freq.

 

Andrew Johansen Melbourne Australia


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