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Upgrading mount... iOptron CEM120

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#76 gotak

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Posted 05 February 2019 - 08:59 AM

For sure they aren't bringing out the mounts and setting up for an evening's test each production run, especially considering how fiddly PEMPro can be with iOptron mounts. They claim to use an encoder solution. I suspect they have a rig to measure the PE at some point in the assembly process.



#77 rgsalinger

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Posted 05 February 2019 - 09:43 AM

With the encoder versions, PE is very low because the encoders are running many times a second to correct any delta between where the motor thinks that the mount is and where the encoders say that it actually is.

I also think that the encoders should work to remove any backlash automatically and quickly. At least I have never detected even the slightest backlash with my EC2. Normally in a GEM  backlash happens in the DEC axis which is why that second encoder comes in handy. 

 

Rgrds-Ross


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#78 DuncanM

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Posted 06 February 2019 - 01:56 PM

So iOptron PE curve matches field test result, maybe they also use PEMPro. When you reduced the PE from 6" to 4.82" did the curve keep the same shape or change?

Congrats your much better than spec copy. 

The curve did change and I'll post them here but the upper  image needs to have the reported error scaled by .85x:

 

PEtestCem120

 

Do note that some folks have found that PHD's backlash measurement is a bit dodgy.

 

The real way to get proper backlash is to see how much BL comp it actually has to dial in during real guiding. It might be you find that it is actually a very slight amount that makes it unnecessary to use compensation.

Yes, I tested backlash with Astroart's autoguider and it seems very minimal. It was extremely windy last night and precise testing was near impossible, even with the mount in my RoR observatory.


Edited by DuncanM, 06 February 2019 - 02:11 PM.


#79 amoncayo

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Posted 06 February 2019 - 06:28 PM

I used my EC2 on Sunday night. The seeing was terrible. Guiding in both axes was around .2 arc seconds which is what I've been getting since I bought the mount. It worked this well out of the box.The original software demons have been sent back to where they belong and the operation is smooth as butter. It's just a better mount than my MX+ which cost so much more in terms of performance. I've had loads ranging from 15 pounds (now) to over 60 pounds on it - same performance. It's hard to believe but, service and unproven longevity aside, this is the new "premium" mount. (A little heavy though and I've never used the Tri-pier - mine is mounted on a PierTech2 pier.)

Rgrds-Ross

Hi Ross,

 

When I grow up and have a bit more saved money, I'm gonna have to buy a second CEM120. This time I'll make sure to scrape the barrel and get the extra few $ to purchase the EC2.

 

For now, I can only envy all of you EC and EC2 users.. I'd love to see 0.2-0.3" night after night! Maybe I need to move? Lol.

 

In all seriousness, and as you know, I'm actually contemplating upgrading my non-EC to an EC or EC2.

 

Al


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#80 Corwinmageoin

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Posted 07 February 2019 - 08:08 PM

Sent off my order yesterday.  Dang Chinese New Year making me wait.

.



#81 Beechnut

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Posted 20 September 2019 - 12:34 AM

Hi all,

 

Would someone mind sending me the link or invite to the cem120 group.  Thinking about getting one shortly and would like to learn as much as possible first.

 

thanks,

 

Larry



#82 SgtErnestBilko

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Posted 23 September 2019 - 03:03 PM

Hi all,

 

Would someone mind sending me the link or invite to the cem120 group.  Thinking about getting one shortly and would like to learn as much as possible first.

 

thanks,

 

Larry

Me too.... my finger is ready to press the "go" button but I am waiting on feedback from iOptron via my dealer on firmware, oscillation and interatction with guiding software..... given the problems outlined by others on this forum.



#83 rgsalinger

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Posted 23 September 2019 - 04:55 PM

I'm not having any trouble with my mount at this point with a light load on it. I would not yet recommend that mount with encoders until I have been able to reload my PW 12.5 onto it and see that the mount performs properly. Having said that, if you bought one, you should load it down heavily and see how it works that way. If it's good then it's good.



#84 gotak

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Posted 24 September 2019 - 06:27 AM

When Ross says that it means you need to take fast video and guide traces using 0.5s exposures or faster to see if your mount has any of the oscillation or SDE issues.

If it does and it's above the spec you should return the mount right away. Don't get stuck in EV purgatory like some of us with mounts we can't return and no fixes in sight.
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#85 SgtErnestBilko

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Posted 29 September 2019 - 01:14 PM

Me too.... my finger is ready to press the "go" button but I am waiting on feedback from iOptron via my dealer on firmware, oscillation and interatction with guiding software..... given the problems outlined by others on this forum.

Not looking good for a 120EC2 purchase, my dealer has had no respoense from iOptron.



#86 rgsalinger

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Posted 29 September 2019 - 01:59 PM

I've been tracking this carefully and I have to say that iOptron seems to be unable to duplicate the poor guiding/tracking results that some people have had with their own testing. They have not released any new firmware for over two months for the mount. I'm running the next to latest version without any issues at all, but with a light (30 pounds ) load. It's a big deal for me to move my equipment again or I'd do some heavy load testing myself.

 

People reporting problems with these mounts seem to resort to looking at logs and running analytical software way too fast for my taste. That method assumes that everything else is OK in the first place. I'm not seeing people take a more organized approach to seeing what's what. The way to debug problems like this is to substitute components and/or strip down systems to their basics. I could go on and on but I keep wondering how good people are at debugging their issues these days. My own experience in debugging things tells me that you can't just assume that everything is fine because your rig worked until you bought your CEM120EC2. Boy did I have to eat my hat when I realized that the camera fan in my heavy rig was causing the oblong stars. 

 

One other person I've been working with - again with a modest load (maybe 45 pounds) has no trouble at all. However,  he, like me, uses MaximDL to guide and not PHD. His problem was that he needed a guiding tutorial. My own system turned out to have a camera fan problem - mount oscillation is not proven at all with my rig.

 

I bought my mount because I was curious about what it would do versus the high priced systems. (I own a Paramount and have used AP systems quite a bit.) Until I put the heavy load on the system, it worked at least as well as my Paramount which cost 3000 dollars more. It also had more capacity (in theory). Given the costs of labor in China versus the USA it made a lot of sense to me that iOptron could deliver equal quality for a lot less money. It will probably next week when I have helpers available to me to run a test.

 

Rgrds-Ross



#87 gotak

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Posted 29 September 2019 - 08:59 PM

I've been tracking this carefully and I have to say that iOptron seems to be unable to duplicate the poor guiding/tracking results that some people have had with their own testing. They have not released any new firmware for over two months for the mount. I'm running the next to latest version without any issues at all, but with a light (30 pounds ) load. It's a big deal for me to move my equipment again or I'd do some heavy load testing myself.

 

People reporting problems with these mounts seem to resort to looking at logs and running analytical software way too fast for my taste. That method assumes that everything else is OK in the first place. I'm not seeing people take a more organized approach to seeing what's what. The way to debug problems like this is to substitute components and/or strip down systems to their basics. I could go on and on but I keep wondering how good people are at debugging their issues these days. My own experience in debugging things tells me that you can't just assume that everything is fine because your rig worked until you bought your CEM120EC2. Boy did I have to eat my hat when I realized that the camera fan in my heavy rig was causing the oblong stars. 

 

One other person I've been working with - again with a modest load (maybe 45 pounds) has no trouble at all. However,  he, like me, uses MaximDL to guide and not PHD. His problem was that he needed a guiding tutorial. My own system turned out to have a camera fan problem - mount oscillation is not proven at all with my rig.

 

I bought my mount because I was curious about what it would do versus the high priced systems. (I own a Paramount and have used AP systems quite a bit.) Until I put the heavy load on the system, it worked at least as well as my Paramount which cost 3000 dollars more. It also had more capacity (in theory). Given the costs of labor in China versus the USA it made a lot of sense to me that iOptron could deliver equal quality for a lot less money. It will probably next week when I have helpers available to me to run a test.

 

Rgrds-Ross

 

Ok logs and such maybe some folks don't trust. How about a video at 30 fps? Same result with or without fans and over two separate optical trains with the same result. With the video and PHD2 both in agreement there's a 5 seconds period in the movement.

 

https://1drv.ms/v/s!...lY1dxJ?e=OfT7k7

 

Watch it, place a cursor or a corner of another window by the star and watch the entire clip. Tell me what you think that star looks like on a long exposure. 

 

The SDE oscillation is not a myth. Under some circumstance you can avoid seeing it.

 

Here's what stars looks like with it:

 

stars_cem60ec.jpg


Edited by gotak, 29 September 2019 - 09:11 PM.

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#88 cytan299

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Posted 29 September 2019 - 09:23 PM

Hi guys,

  As a follow up to Ross’ criticism of end users who may not know what they are doing, I have a question: has iOptron ever published any demo of any of their EC mounts tracking with guiding simultaneously using long focal length heavy telescopes+camera? Perhaps if they haven’t, they should so that they can show that their mount actually works as advertised. 

 

  Astro-physics is well known for doing this. See their yahoo group on their upcoming Mach2. If iOptron can do what AP does, it will allay some doubts about whether their mount works as described. People can then use what they set up as starting points to see whether it is pilot error or hardware problems.

 

Just a thought.

 

cytan


Edited by cytan299, 29 September 2019 - 09:25 PM.

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#89 gotak

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Posted 29 September 2019 - 09:38 PM

Not looking good for a 120EC2 purchase, my dealer has had no respoense from iOptron.

Your dealer sounds like an up standing guy. Mine tells me he can do nothing for me and claims to have never heard of any SDE issues, and now completely ignores me. I'll be thinking long and hard before doing any more business with him.



#90 rgsalinger

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Posted 29 September 2019 - 10:01 PM

Well, what I see is that the video shows a star that's moving in all directions. How that proves that it's SDE and nothing  else is beyond me, given the dearth of information about the video. It seems to show both up/down and left right movements. That would make it inconsistent with the screen shot show above which looks like elongation (movement) in only one axis. Again, with no information how can anyone draw a conclusion about what's actually going on. Maybe the seeing was bad the night the video was taken. Was there even a seeing monitor present in the observatory? Maybe the pier is unstable. What is the FWHM of the image shown? 

 

To me this is, respectfully, just more of the same. Without step by step changes and analysis, I don't see that a convincing case is being made to the vendor. I also don't think that the vendor is behaving the way that they should. iOptron has been very opaque about the nature of their testing. We have not seen a single long exposure long focal length image taken with (say) 80 pounds on the system. Leaving aside whether or not some would believe the vendor, they have never presented a shred of evidence that the complainers are wrong. 

 

I know that in my particular case, I was wrong about the mount. I had the same problem when I moved the imaging system to a different mount. I don't think that's been tried. I used 3 different guiding systems and they all showed the same exact thing. I checked the collimation on my scope. It was almost perfect. Yet I blamed the mount. My suggestion to them is to try to change things out in an organized step by step way and put the vendor into a box. 

 

Rgrds-Ross



#91 cytan299

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Posted 30 September 2019 - 02:38 AM

Well, what I see is that the video shows a star that's moving in all directions. How that proves that it's SDE and nothing  else is beyond me, given the dearth of information about the video. It seems to show both up/down and left right movements. That would make it inconsistent with the screen shot show above which looks like elongation (movement) in only one axis. Again, with no information how can anyone draw a conclusion about what's actually going on. Maybe the seeing was bad the night the video was taken. Was there even a seeing monitor present in the observatory? Maybe the pier is unstable. What is the FWHM of the image shown? 

 

To me this is, respectfully, just more of the same. Without step by step changes and analysis, I don't see that a convincing case is being made to the vendor. I also don't think that the vendor is behaving the way that they should. iOptron has been very opaque about the nature of their testing. We have not seen a single long exposure long focal length image taken with (say) 80 pounds on the system. Leaving aside whether or not some would believe the vendor, they have never presented a shred of evidence that the complainers are wrong. 

 

I know that in my particular case, I was wrong about the mount. I had the same problem when I moved the imaging system to a different mount. I don't think that's been tried. I used 3 different guiding systems and they all showed the same exact thing. I checked the collimation on my scope. It was almost perfect. Yet I blamed the mount. My suggestion to them is to try to change things out in an organized step by step way and put the vendor into a box. 

 

Rgrds-Ross

Well, for those who have skin in the game (I don’t, but I’m known to be a rabble rouser :) ), I’d suggest that owners of the affected EC mounts ask iOptron to do a video demo together with PhD logs for their EC mounts fully loaded with a long fl telescope+camera. Of course there will be some skepticism of their results, but it will go a long way to assure owners of questionable mounts that it is pilot error and not hw problems.

 

But IMO, I really believe that the mechanical tolerances of iOptron mounts, at the medium entry price point, precludes a simple feedback algorithm that works for all the EC mounts. Ross, you may have lucked out, while gotak seems to be out of luck. This is exactly what happened to me: my non EC cem60 and zeq25 were both POS while posters here swear that they both work great. And that’s why, I’ve always said that buying iOptron is a cr*p shoot.

 

cytan


Edited by cytan299, 30 September 2019 - 04:29 AM.


#92 gotak

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Posted 30 September 2019 - 05:49 AM

Ross stick a window next to that star in the video. It takes a few seconds for it to move left to right but it does. Left to right is RA.

I'll show the PHD screen later today if you must to be convinced. It's a sine wave in RA.

And to counter your argument about other things impacting this oscillation. There was one fw version 20190624 which completely removed it and it shows up as such in the video and PHD2. This is all with the exact same OTA in the exact same session where switching the FW between 20190624 vs other versions can produce or remove the SDE. If it's caused by other factors that should never be the case.

Edited by gotak, 30 September 2019 - 05:49 AM.


#93 rgsalinger

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Posted 30 September 2019 - 10:20 AM

Well, this confuses ME even more. Let me take your comments in turn. First, are we discussing a slow drift in tracking rate or SDE? My limited understanding of SDE (Calc taken in 1962/3/4) is that it is a high frequency oscillation which shows up as an elongated star. You now seem to describe the issue as one of slow drift, is that correct?. Slow drift would not show up in long guided exposures, it would guide out. Second, I actually used on my mount the firmware (190624) that you say "fixed" your problem. It made my mount perform poorly. It certainly did "something". What I saw (from memory) was a seesaw movement that could not be controlled by guiding and I reverted to what I had been running  (190316). I got another release 190716 but that was after I switched my system over to the Paramount and that's where I'm at today.

 

Frankly, I would like to see a guiding graph from something other that PHD. I'll tell you why. I think that PHD has been a wonderful contribution by the authors to astro-photography. However, there is no reason to assume that if PHD shows a problem it's not a problem in PHD. PHD has a myriad of little switches and settings. It's unlike the guiding software that I use - MaximDL or the SKYX which have just a few, very obvious, settings. So, that would be my first port of call when there is a guiding problem, switch guiding software. In fact, that's precisely what I did when I first saw my mount produce oval stars - went over to the SKYX and then to PHD. They all gave the same results. 

 

At the same time you did not explain why seeing, a bad calibration, or fan vibrations, pier issues, etc are not  possible issues if the problem is SDE. Seeing would be perfectly consistent with inconsistent results. I had this happen just last night using my Paramount.

 

Is this from your own mount or are you getting this information about the CEM120EC2 from someone else and reporting what they SAY that they did? 

 

Again, I think that iOptron is being an **** here. They will not provide a means of turning on/off the encoders - acid test. They will not respond with details about their testing practices and do not provide a guide, as SB does, to debugging their mounts. If you read the release notes for the firmware releases, they are gibberish. (Not that I could produce a Mandarin document, but I'm not selling stuff into China.) All of this is a mistake on their part if you want to sell observatory class mounts. I made the argument a long time ago that the reason I would buy an AP or SB mount is support, period. My CEM guides just like my Paramount, but if there are problems with a Paramount there's a support forum, people you can call on the phone and a huge sophisticated user community to help if you have a problem or are just confused.

 

When I was having my problem with my mount, I kept sending my test process and results to iOptron. My mount was under warranty. I found phone numbers at iOptron and called people. I complained to the Massachusetts consumer protection folks. Eventually iOptron agreed to and sent me an RMA and to inspect the mount. After I found what I believe to be the problem (bad camera fan still to be "proven") I never sent the mount in for repair. I'm pretty sure that they did that because they could see that I had done a careful sequential troubleshooting exercise. I'm seeing no evidence of this being done here. That's my real point, you might get a better result from doing a carefully thought out test plan. I mean this is a 7000 dollar purchase and it should just work.

 

If you want to fly out here this week or drive out to the observatory with a big OTA, we can run some tests on my mount. I won't have a helper available to me until the weekend. In the meantime I'll try to get iOptron to tell me what the "best" release is these days of the firmware.  

 

Rgrds-Ross



#94 Michaeljhogan

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Posted 30 September 2019 - 10:29 AM

Well, this confuses ME even more. Let me take your comments in turn. First, are we discussing a slow drift in tracking rate or SDE? My limited understanding of SDE (Calc taken in 1962/3/4) is that it is a high frequency oscillation which shows up as an elongated star. You now seem to describe the issue as one of slow drift, is that correct?. Slow drift would not show up in long guided exposures, it would guide out. Second, I actually used on my mount the firmware (190624) that you say "fixed" your problem. It made my mount perform poorly. It certainly did "something". What I saw (from memory) was a seesaw movement that could not be controlled by guiding and I reverted to what I had been running  (190316). I got another release 190716 but that was after I switched my system over to the Paramount and that's where I'm at today.

 

Frankly, I would like to see a guiding graph from something other that PHD. I'll tell you why. I think that PHD has been a wonderful contribution by the authors to astro-photography. However, there is no reason to assume that if PHD shows a problem it's not a problem in PHD. PHD has a myriad of little switches and settings. It's unlike the guiding software that I use - MaximDL or the SKYX which have just a few, very obvious, settings. So, that would be my first port of call when there is a guiding problem, switch guiding software. In fact, that's precisely what I did when I first saw my mount produce oval stars - went over to the SKYX and then to PHD. They all gave the same results. 

 

At the same time you did not explain why seeing, a bad calibration, or fan vibrations, pier issues, etc are not  possible issues if the problem is SDE. Seeing would be perfectly consistent with inconsistent results. I had this happen just last night using my Paramount.

 

Is this from your own mount or are you getting this information about the CEM120EC2 from someone else and reporting what they SAY that they did? 

 

Again, I think that iOptron is being an **** here. They will not provide a means of turning on/off the encoders - acid test. They will not respond with details about their testing practices and do not provide a guide, as SB does, to debugging their mounts. If you read the release notes for the firmware releases, they are gibberish. (Not that I could produce a Mandarin document, but I'm not selling stuff into China.) All of this is a mistake on their part if you want to sell observatory class mounts. I made the argument a long time ago that the reason I would buy an AP or SB mount is support, period. My CEM guides just like my Paramount, but if there are problems there's a support forum, people you can call on the phone and a huge sophisticated user community to help if you have a problem or are just confused.

 

When I was having my problem with my mount, I kept sending my test process and results to iOptron. My mount was under warranty. I found phone numbers at iOptron and called people. I complained to the Massachusetts consumer protection folks. Eventually iOptron agreed to and sent me an RMA and to inspect the mount. After I found what I believe to be the problem (bad camera fan still to be "proven") I never sent the mount in for repair. I'm pretty sure that they did that because they could see that I had done a careful sequential troubleshooting exercise. I'm seeing no evidence of this being done here. That's my real point, you might get a better result from doing a carefully thought out test plan. I mean this is a 7000 dollar purchase and it should just work.

 

If you want to fly out here this week or drive out to the observatory with a big OTA, we can run some tests on my mount. I won't have a helper available to me until the weekend. In the meantime I'll try to get iOptron to tell me what the "best" release is these days of the firmware.  

 

Rgrds-Ross

What am i doing wrong my mount will go to pleiades but wont go to anything else iv done everything correct i think its a dud can you give me

good stars to choose the stars i choose are way out on the very edge of FOV im sorry i got this mount i should of got the CGX-L


Edited by Michaeljhogan, 30 September 2019 - 12:01 PM.


#95 gotak

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Posted 30 September 2019 - 12:07 PM

Well, this confuses ME even more. Let me take your comments in turn. First, are we discussing a slow drift in tracking rate or SDE? My limited understanding of SDE (Calc taken in 1962/3/4) is that it is a high frequency oscillation which shows up as an elongated star. You now seem to describe the issue as one of slow drift, is that correct?. Slow drift would not show up in long guided exposures, it would guide out. Second, I actually used on my mount the firmware (190624) that you say "fixed" your problem. It made my mount perform poorly. It certainly did "something". What I saw (from memory) was a seesaw movement that could not be controlled by guiding and I reverted to what I had been running  (190316). I got another release 190716 but that was after I switched my system over to the Paramount and that's where I'm at today.

 

Frankly, I would like to see a guiding graph from something other that PHD. I'll tell you why. I think that PHD has been a wonderful contribution by the authors to astro-photography. However, there is no reason to assume that if PHD shows a problem it's not a problem in PHD. PHD has a myriad of little switches and settings. It's unlike the guiding software that I use - MaximDL or the SKYX which have just a few, very obvious, settings. So, that would be my first port of call when there is a guiding problem, switch guiding software. In fact, that's precisely what I did when I first saw my mount produce oval stars - went over to the SKYX and then to PHD. They all gave the same results. 

 

At the same time you did not explain why seeing, a bad calibration, or fan vibrations, pier issues, etc are not  possible issues if the problem is SDE. Seeing would be perfectly consistent with inconsistent results. I had this happen just last night using my Paramount.

 

Is this from your own mount or are you getting this information about the CEM120EC2 from someone else and reporting what they SAY that they did? 

 

Again, I think that iOptron is being an **** here. They will not provide a means of turning on/off the encoders - acid test. They will not respond with details about their testing practices and do not provide a guide, as SB does, to debugging their mounts. If you read the release notes for the firmware releases, they are gibberish. (Not that I could produce a Mandarin document, but I'm not selling stuff into China.) All of this is a mistake on their part if you want to sell observatory class mounts. I made the argument a long time ago that the reason I would buy an AP or SB mount is support, period. My CEM guides just like my Paramount, but if there are problems with a Paramount there's a support forum, people you can call on the phone and a huge sophisticated user community to help if you have a problem or are just confused.

 

When I was having my problem with my mount, I kept sending my test process and results to iOptron. My mount was under warranty. I found phone numbers at iOptron and called people. I complained to the Massachusetts consumer protection folks. Eventually iOptron agreed to and sent me an RMA and to inspect the mount. After I found what I believe to be the problem (bad camera fan still to be "proven") I never sent the mount in for repair. I'm pretty sure that they did that because they could see that I had done a careful sequential troubleshooting exercise. I'm seeing no evidence of this being done here. That's my real point, you might get a better result from doing a carefully thought out test plan. I mean this is a 7000 dollar purchase and it should just work.

 

If you want to fly out here this week or drive out to the observatory with a big OTA, we can run some tests on my mount. I won't have a helper available to me until the weekend. In the meantime I'll try to get iOptron to tell me what the "best" release is these days of the firmware.  

 

Rgrds-Ross

It's my CEM60EC but there is I believe at least one CEM120EC that's showing the same problems with SDE.

 

Anyhow Ross I think I'll put all the info into another thread. There are actually multiple issues with EC tracking which appears to be in various state of fixed or not depending on which copy of the mount.

 

I don't think other than you anyone else has a optical train related elongation issue. However, you seem convinced that it is setup for your own reasons.

 

For me it is simple:

 

  • Two separate optical train both shows SDE with magnitude of 2" p-p
  • Fans or not you see SDE
  • Video and PHD2 agrees there is consistent movement back and forth in RA direction. 
  • When running PHD2 GA with no guide inputs SDE is clearly apparent and I see the RA magnitude of 2" p-p constantly over many minutes in many different DEC and RA orientations. While DEC trace under 1" p-p during these runs. This is with 0.5second exposures. 
  • Fixes for CEM60EC as per iOptron are the same as the ones under CEM120EC and we do know of that one person who's 120 SDE like my 60 was not resolved (the other Ross). 

 

If it is anything other than an inherent problems with the mount or software, you'd think some of us would have solved it. We haven't so the problem remains and it is something people should be fully aware of before they buy any EC mount in my opinion. 


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#96 rgsalinger

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Posted 30 September 2019 - 12:41 PM

Actually, I would think that some have unsolved user or environment problems, but that there may also be mounts out there that actually have mount/firmware problems. I think that both cases are being lumped together because of poor trouble shooting techniques. That,  in turn, gives iOptron the ability to ignore the real issues in favor of suggesting simple changes in aggression. 

 

These mounts are bound to have quality variations and the firmware may also be faulty under some circumstances that are hard to define. I am not at all ruling out that you have a real problem at all. Rather I'm not able to see that you've really controlled all of the variables that you could have. You keep using the same guiding software. You are using the same pier (AFACT). You are using identical imaging trains (per your earlier email). I don't know what power supply you have in the observatory or what you seeing conditions are out there.

 

I looked at the video and I saw movements in all directions consistent with poor seeing. That would give you and PHD and the graph exactly the same symptoms that you are attributing to the mount. I'll wait for that other thread. I see this all the time on mediocre nights with a 5 meter focal length scope that I use. I suggest that if you can do some additional substitutions you make a much stronger case with iOptron. 

 

At least we agree that the vendor has been remiss in supporting these mounts. Until they improve their act, I can't recommend the EC mounts unless someone (like me) is a gambler. That's why I bought my mount - out of curiosity to see if they could make something as good as my Paramount for 3K less and with more USB ports. 

 

Rgrds-Ross



#97 alphatripleplus

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Posted 30 September 2019 - 12:45 PM

Everyone please keep the discussion here on topic to just the CEM120 mount. There are  several ongoing CEM60 threads where similar issues have been raised and discussed. It may make sense to just start a thread on common issues affecting all /some of the EC mounts if there is interest. Thanks for your co-operation.



#98 RossW

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Posted 01 October 2019 - 01:01 AM

I'm unfortunately limited in what I can say because I am, even after 7 months, still in a David and Goliath battle with iOptron regarding my 120EC2. I'll update my EC2 thread with all the gory details when the outcome is finalised.

 

Ross S, in general I agree that many of the problems faced by new users of astro equipment are often self-inflicted "own goals", and I agree one needs to take a methodological approach to problem-solving these issues by stripping down the equipment to its most basic functional configuration. However in the case of iOptron encoder mounts I believe there is now ample evidence posted by experienced users that points to very real problems with these mounts, irrespective of whether the problems are caused by faulty hardware, electronics, or firmware, namely:

  1. high-frequency resonance, variable in frequency but usually around 3 to 5 Hz;
  2. low-frequency oscillation; 0.3Hz for the 120EC/EC2 at the SDE period of 3.3 seconds
  3. guiding instability in both RA and Dec.

It took literally an avalanche of complaints to encourage iOptron to take a serious look at problems (1) and (3) above, and to their credit they appear to be approaching the point where these two problems are resolved for the majority of users. Fortunately these two problems were solvable via firmware updates alone.

 

Unfortunately (2) above remains unresolved, and because so few users are experiencing this fault mode it would appear iOptron are not interested in spending sufficient time and resources solving the problem, whether that be via mount service/upgrade, mount replacement, or refund.

 

In case readers aren't familiar with how debilitating this SDE oscillation is to imagers using long focal length scopes, please take a look at this video:

 

https://www.youtube....R9GXaAI&index=7

 

You're witnessing here a 3 to 5 arc-sec peak-to-peak SDE oscillation, constant in frequency and always around this magnitude. It exists despite using two completely separate scopes (Meade 16" ACF and Edge HD 1100) and imaging trains (no equipment moved between scopes). No, PhD settings are not the cause of this oscillation; there is no guiding occurring here; PhD is simply measuring star movement. I see the same movement when using SharpCap (thus no PhD involvement). Four versions of firmware dating over the last year show no improvement, so I'm not confident the problem can be solved via firmware updates, although Gotak's recent post gives me some hope.

 

Did I mention my light subs look *@#! terrible? Eccentricities usually range from 0.5 to 0.9. My $1,400 SkyWatcher AZ-EQ5 provides me with better subs.

 

It has been more than frustrating working with iOptron over the last 6 months (frustrating for iOptron too I'm sure). What is more frustrating is the reality that this mount is but one step away from being, by far, the best bang-for-your-buck encoder mount on the market. Unfortunately that one last step is a binary option with very different outcomes, one being imaging heaven, while the other is imaging hell with unusable subs and a mount that the maker appears unwilling to acknowledge is out of spec.

 

So at this stage I'm burdened with a $7,000 mount that performs worse than the standard CEM120 and my other cheaper, non-encoder mounts. To the OP of this thread, are you feeling lucky? And can you trust a company that appears (based on my experience to date) reluctant to honour their warranty?


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#99 rgsalinger

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Posted 01 October 2019 - 10:09 AM

Other Ross ----

 

I'm not saying that there may not be a problem with some of these mounts at all. I'm also not giving iOptron kudos for their support practices. They certainly never offered to log on to my system to check it out when it failed to perform satisfactorily. More than anything, though, I'm baffled as to your customer support experience!!! If it's just your mount, have you just asked them to take it back and give you a new one? What did they say? If you could PM me I'd love to compare notes. 

 

Let me be a bit stubborn here and ask a few questions about what testing has been done to date. My intent is more than anything to see if one of them might give you some better information or point to a solution. 

 

First, when you measured the oscillation in the video what was the reported seeing on that night? I say this because I have seen similar oscillations on a large scope equipped with Renishaw encoders on nights with poor (but not obviously bad) seeing. I have the advantage of using an observatory that has a seeing monitor in place, so I can check the weather. I suspect that your answer will be that the problems simply persist night after night. Hence, it cannot be related to anything other than the mount.

 

Second, have you put the system on a KNOWN stable pier? I say this because I went through a year of poor performance with my MX+ due to a faulty pier recently that experts were unable to diagnose. I can also tell you that the guiding on the MX+ at long focal lengths is a function of the quality of the pier's stability and I think that the same will be true of the CEM120EC2. Mine is sitting on a 48x48x36 deep concrete pad isolated from the rest of the observatory, for example. 

 

Third, have you put the same imaging system on a different mount known to be working well and compared the results? I ask this because my recent experience showed this to be the acid test to separate out the mount from the imaging system. I note that both of your scopes are SCT's and have moving mirrors, so maybe it's a problem with that mount and the SCT design. I say that because I saw none of this with my mount and my CF tubed CDK or with my Refractors (TV127 and AP155).

 

Fourth, with respect to the long subs, have you used any other guiding software to control the mount? I ask this for two reasons. First, my math is bad now and I keep wondering if it's the case that the issues that show up under your test conditions necessarily mean that the end results will be poor. Second, because I do not trust PHD results because there are just too many parameters and just one bad setting can give you a bad guiding result. 

 

Finally, when the graph was produced, what camera and imaging technique was being used? I assume that the camera was not a guide camera off axis but rather the main camera in a completely stripped down system but you don't mention the setup. 

 

You mention three reported problems. I can honestly say that I have never seen even one of them manifested in the results I've gotten from my mount with long exposures. So, I'm convinced now that I have to put my system back together and test it one more time with my now known working imaging train. That won't help anyone else though if the issue is really about things like resonant frequency of the system.

 

Rgrds-Ross



#100 rgsalinger

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Posted 02 October 2019 - 01:39 PM

iOptron Testing.PNG

 

Five minute guided subs at 2.5 meters of focal length with 55 pounds on the mount. Not the improvement in eccentricity as the nigth work on. I attribute this to cool down of the mirror and stabilization of the atmosphere. I'm now 90 percent convinced that my copy of this mount works for that much weight and focal length. 

 

Rgrds-Ross


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