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iOptron CEM60, First Impressions

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#851 tazer

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Posted 05 July 2014 - 05:51 PM

As I said, it's not bad, but there's some definite elongation there. What bothers me is the fact that RA almost completely refuses to respond for 45s at 100% aggression and max pulse of 1500ms. It's not what you'd expect for a $2500 mount as even the CG5 ASGT doesn't do that.
 

#852 Astronewb

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Posted 05 July 2014 - 05:54 PM

Is there something I'm missing?

With the mount guide rate set to .80 and the calibration setting at 2500, the mount should calibrate in 5-6 iterations? Letting it run longer is just cutting down on your imaging time.

You have your Min Motion settings at .50 pixels, at that setting your image is already ruined by the time a guide correction is issued. Try .15 or .20.

Your Mx RA and Mx DEC are very high at 1500 each. Try the default 1000/150 and adjust RA Agg down from 100% to smooth out the graph. If you have to lower it to 75% or lower, then reduce the Mx RA and/or Mx DEC and return to 100% RA Aggression and start over.

I don't know what might be causing those runaway spikes, but I would start by reloading the guide camera drivers. I had various issues with a SSAG/drivers, and some nights had to disconnect the cables and reconnect several times to reload the drivers to guide correctly. Since moving to a Lodestar and QHY5L-II those issues have completely gone away.

Good luck your next clear night out.

Regards...Paul
 

#853 Raginar

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Posted 05 July 2014 - 06:10 PM

I use min motion of .05. Seems to work pretty good on my stars.
 

#854 tazer

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Posted 05 July 2014 - 07:39 PM

You have your Min Motion settings at .50 pixels, at that setting your image is already ruined by the time a guide correction is issued. Try .15 or .20.


.50 was experimental but I haven't lowered it down to .15 yet. I assumed that the lower you go the more susceptible guiding is to seeing. Here in central NC the seeing is usually poor.


Your Mx RA and Mx DEC are very high at 1500 each.


I generally leave RA aggressiveness at 75% but when I get frustrated with lack of response from the mount I boost it up to see if it has any effect. You can see in the graph that even with aggressiveness at 100% and 1500ms max duration that RA corrections are ineffective at times. I'm not sure why.


Since moving to a Lodestar and QHY5L-II those issues have completely gone away.


I'm looking at picking up a QHY5L-II for increased sensitivity. Also, with a 1.25" eyepiece adapter, it makes focusing much easier for me than with the SSAG.

It's supposed to be nice here tonight so I'm going to do some more experimenting. I think I'll give the new ASCOM drivers another shot and see if they continue to crash PHD2.

As always, thanks for the feedback.
 

#855 Astronewb

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Posted 05 July 2014 - 08:29 PM

I'm looking at picking up a QHY5L-II for increased sensitivity.


Great choice, I prefer it over my Lodestar. Smaller fov, but much sharper guide stars. The drivers are excellent also.

Regards...Paul
 

#856 Dan Finnerty

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Posted 05 July 2014 - 08:40 PM

I don't know what might be causing those runaway spikes, but I would start by reloading the guide camera drivers. I had various issues with a SSAG/drivers, and some nights had to disconnect the cables and reconnect several times to reload the drivers to guide correctly. Since moving to a Lodestar and QHY5L-II those issues have completely gone away.
Regards...Paul


Last week, with his ZEQ25, my brother was going crazy with similar behavior with PHD2. (can't remember which guide camera he was using). A new PC with newly loaded drivers. Several other people came by and scratched their heads and none of us could figure out what was going on. Eventually we swapped mounts, and my ZEQ exhibited similar behavior. Multiple Dec corrections that the mount would not respond to, then radical over correction and then the same behavior in the opposite direction.

When he got home, he purged all drivers for guide scope and PHD2 and carefully downloaded and reloaded everything. Now everything is working as it should. As soon as I ready your post I started thinking "drivers". Listen to Paul, he is giving good advice. If that does not work, at least you will have eliminated one more possibility.
 

#857 tazer

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Posted 06 July 2014 - 09:27 AM

Thanks for the suggestion but unfortunately I've already reloaded everything (ssag drivers, phd2, phd, ascom) but get the same results. I'll attempt to contact iOptron again and see if they respond but I'm at a loss of what to try next.

It occurred to me that my previous guide graph was around 57 degrees so I should try imaging something lower. After incorporating some of Paul's parameter suggestions I had a go a the Lagoon Nebula and this was the guide graph I got (I was balanced east heavy and my polar alignment was about 5'):

Attached Files


 

#858 orlyandico

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Posted 06 July 2014 - 11:15 AM

is that error in pixels or in arc-seconds?
 

#859 Raginar

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Posted 06 July 2014 - 11:18 AM

Pixels.
 

#860 austin.grant

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Posted 06 July 2014 - 11:37 AM

That's pretty poor guiding, and if he's using the SSAG with the OAG and Mak-Newt, it's even worse than it looks. That combination would put the guiding at 1.47-arcseconds/pixel, or over 3-arcseconds of RMS error.
 

#861 tazer

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Posted 06 July 2014 - 01:35 PM

Yep, that's pixels.

Austin, you're correct regarding my setup. 731mm Mak-Newt guided with SSAG via TOAG. That's about 1.45" ppx by my calculations.

I don't expect a flat guide graph but I'm getting wild swings in RA that PHD/PHD2 can't counteract effectively. Even at 100% RA aggressiveness there are periods where RA just seems unresponsive.

Polar alignment was done via the handset, PHD Lab estimates PAE was about 5', the tripod was well leveled, there was 0mph of wind, seeing was above average for once, RA was balanced east heavy, DEC was near perfect balanced, and the total imaging weight was 19.4lbs.

The only thing I can think of is that RA is 'soft' when tracking at sidereal. When the mount is off I can lightly press the scope in RA and it gives just a bit. If I thump it, the whole scope vibrates for a sec. This doesn't happen in DEC. I'd expect a mount of this weight class loaded at 1/3 capacity to be rock solid.
 

#862 daran0815

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Posted 06 July 2014 - 06:04 PM

I don't expect a flat guide graph but I'm getting wild swings in RA that PHD/PHD2 can't counteract effectively. Even at 100% RA aggressiveness there are periods where RA just seems unresponsive.


That does sound bad. Can't remember where I read it, but someone had guiding problems that went away when he directly connected to his equipment, instead of using the input panel. Probably not your problem, but easy enough to check?
 

#863 RandyC

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Posted 06 July 2014 - 07:27 PM

I've always had an unresponsive RA in my ZEQ25 ever since I got it. The mount sometimes ignores the first 3-4 pushes from the HC. But tracking and guiding have always been okay. This issue hasn't seemed to affect the mount in action.
 

#864 x6gas

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Posted 07 July 2014 - 01:40 AM

Thanks for the suggestion but unfortunately I've already reloaded everything (ssag drivers, phd2, phd, ascom) but get the same results. I'll attempt to contact iOptron again and see if they respond but I'm at a loss of what to try next.

It occurred to me that my previous guide graph was around 57 degrees so I should try imaging something lower. After incorporating some of Paul's parameter suggestions I had a go a the Lagoon Nebula and this was the guide graph I got (I was balanced east heavy and my polar alignment was about 5'):


Hi Taser,

Just wondering but have you tried guiding with PHD rather than PHD2 and are you seeing the same results?

Here's why I ask: Last night I set up and had a polar align offset of 0.5' in DEC so there shouldn't be too much work for the guiding program to do on that axis. What I saw, though, was a whole bunch of spikes on DEC. Oddly not as a result of guide commands. It wasn't windy so I was curious and switched over to PHD... and then no spikes on DEC.

I am wondering if there is some kind of software issue with PHD2 that the CEM60 doesn't like?

Course this was just one night so this observation may be spurious, but something weird was going on!
 

#865 tazer

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Posted 07 July 2014 - 07:56 AM

Yep, I did try PHD as well but got a similar graph. What's seems odd to me was that although RA has always been like the graphs I posted, DEC has previously been nearly flat. I'd blame the recent firmware update but I don't know that anyone else is having the issues I'm facing.

I did loosen the RA belt (at iOptron supports direction) to alleviate the RA motor stalls I was dealing with. Then again, the RA guiding issues predate that change so I'm at a loss as to what's going on.
 

#866 Tony Finnerty

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Posted 07 July 2014 - 04:50 PM

Hi Taser,

Just wondering but have you tried guiding with PHD rather than PHD2 and are you seeing the same results?

Here's why I ask: Last night I set up and had a polar align offset of 0.5' in DEC so there shouldn't be too much work for the guiding program to do on that axis. What I saw, though, was a whole bunch of spikes on DEC. Oddly not as a result of guide commands. It wasn't windy so I was curious and switched over to PHD... and then no spikes on DEC.

I am wondering if there is some kind of software issue with PHD2 that the CEM60 doesn't like?

Course this was just one night so this observation may be spurious, but something weird was going on!


This sounds so much like my experience with PHD2 under Windows 8.1, using a QHY5L-II to guide a ZEQ25. Dec spikes that nothing could fix, including cleaning and tuning both mount axes, down to the tiny gears in the planetary gearbox, and swapping drive motors with their planetary gearboxes, over several nights of testing.

As mentioned here by my brother Dan, I had a good night after reloading all drivers and software and thought I had solved the problem. The next night, the Dec spikes were back. It turns out that fortuitously I had a near-perfect polar alignment on the good night with very little Dec drift, so PHD2 issued few Dec commands and there were no software-caused spikes.

The last thing I expected was a problem with PHD2 because Paul Chasse gets excellent guiding from this combination. Finally, last night before the clouds shut me down, I tried MetaGuide, just to see what would happen without PHD2. I still must learn a lot about how to tune MetaGuide and to interpret its graphs but ... no Dec spikes!

Evidently the current version of PHD2 has a problem.
 

#867 x6gas

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Posted 08 July 2014 - 01:16 AM

Hi Taser,

Just wondering but have you tried guiding with PHD rather than PHD2 and are you seeing the same results?

Here's why I ask: Last night I set up and had a polar align offset of 0.5' in DEC so there shouldn't be too much work for the guiding program to do on that axis. What I saw, though, was a whole bunch of spikes on DEC. Oddly not as a result of guide commands. It wasn't windy so I was curious and switched over to PHD... and then no spikes on DEC.

I am wondering if there is some kind of software issue with PHD2 that the CEM60 doesn't like?

Course this was just one night so this observation may be spurious, but something weird was going on!


This sounds so much like my experience with PHD2 under Windows 8.1, using a QHY5L-II to guide a ZEQ25. Dec spikes that nothing could fix, including cleaning and tuning both mount axes, down to the tiny gears in the planetary gearbox, and swapping drive motors with their planetary gearboxes, over several nights of testing.

As mentioned here by my brother Dan, I had a good night after reloading all drivers and software and thought I had solved the problem. The next night, the Dec spikes were back. It turns out that fortuitously I had a near-perfect polar alignment on the good night with very little Dec drift, so PHD2 issued few Dec commands and there were no software-caused spikes.

The last thing I expected was a problem with PHD2 because Paul Chasse gets excellent guiding from this combination. Finally, last night before the clouds shut me down, I tried MetaGuide, just to see what would happen without PHD2. I still must learn a lot about how to tune MetaGuide and to interpret its graphs but ... no Dec spikes!

Evidently the current version of PHD2 has a problem.


Interesting! I am running a Windows 8.1 machine, PHD2 with a QHY IMG0H as a guidecam. Perhaps there is something in that combo.

I can't get MetaGuide to run on my Windows 8.1 machine though. Perhaps I need to reinstall it...
 

#868 Tony Finnerty

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Posted 08 July 2014 - 11:26 AM

I can't get MetaGuide to run on my Windows 8.1 machine though. Perhaps I need to reinstall it...


I had to install MetaGuide in Windows 8.1 using Windows 7 compatibility mode. MG seems to run fine that way.
 

#869 bseltzer

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Posted 11 July 2014 - 12:33 PM

Have you tried the latest version (5.1.7) of MetaGuide? At least on my Windows 8.1 laptop, it installed cleanly without any tweaks to the compatibility mode or needing to be run as 'administrator'.
 

#870 x6gas

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Posted 11 July 2014 - 01:55 PM

Yes, clean install of 5.1.7. Odd that it installed fine on my other Win 8.1 laptop, but wouldn't install on a new HP Win 8.1 machine. Installing in Win 7 compatibility mode solved it.

Returning to the CEM60 topic - I'm definitely getting odd spikes when guiding with PHD2. Not seen that on my other mounts...

But then I upped the exposure and got the attached. This guided with and OAG at 1960mm. Excited? I was until I realized I was guiding on a hot pixel! :o

Might be clear here tonight so intend to try guiding using AstroArt and possibly MetaGuide to see if I can improve my guided results.

Attached Files


 

#871 Astronewb

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Posted 12 July 2014 - 11:38 PM

Excited? I was until I realized I was guiding on a hot pixel!


Lol, thanks for that. Actually you can trash PHD2 v2.3, as it doesn't have any provision for taking darks..:( I have reverted to PHD2 v2.2a for that reason and also because of DEC guiding issues (it won't).

I was out last night in the full moon testing some spacers on my field flattener and took advantage of the time to also check guiding settings for the CEM60EC.

The CEM60EC definitely likes very low RA Aggression settings and a low Mx RA to perform up to its potential.

Testing was done with a mount guide rate of .80 (wish it were 1.0) and just a polar align and a One Star align. Screenshot of the PHD2 screen:

Posted Imagecem60ec_071214_1370mm by Astronewb2011, on Flickr

I use the pixel scale set at 8 pixels since that's the only scale that lets me make meaningful adjustments to the graph.
Anything smaller drives me nuts, and using the arc-second scale means nothing to me when imaging.

With the QHY5L-II in the Borg 50mm, the image scale is about 3.094 arc-seconds per pixel if you want to do the math.

Here's a single sub of Alfirk, 900 seconds @ 1370mm/F9 using the settings described above:

Posted ImageAlfirk_cem60ec_900secs by Astronewb2011, on Flickr

Oh, the wife and I got out tonight to view the 'super moon' with the ES152. Used a plethora of ES EPs, ranging from 4.7 to 30mm and a Baader 17 and 8-24 zoom. Focusing with the 44"/24 pound ota on the CEM60EC was a dream, no vibrations, just smooth as silk, rock solid. After about an hour I was about 'moon blind' so we packed it in...:)

Cheers and have a great weekend,

Paul
 

#872 tazer

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Posted 13 July 2014 - 07:12 AM

Actually you can trash PHD2 v2.3, as it doesn't have any provision for taking darks..


Paul, the dark creation process is actually greatly improved in v2.3.0. If you go to the Darks menu and select Dark Library it'll bring up a Dark Library Creation dialog. On that dialog box you can select a range of exposure durations and exposure times. When you click Start PHD2 will iterate over each exposure step (which you'd normally see in the exposure drop down) and take as many darks at each step as you've requested. So, for example, you can select 0.5s to 10s with 30 darks for each step and PHD2 will completly automate the building of the dark library for every exposure in-between. There's also a bad pixel map library as well.
 

#873 bseltzer

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Posted 13 July 2014 - 11:08 AM

What tazer said... No trouble producing and using a darks library in PHD2 v2.3

Paul, what is the focal length of your guiding optics?
 

#874 Astronewb

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Posted 13 July 2014 - 11:43 AM

Paul, the dark creation process is actually greatly improved in v2.3.0. If you go to the Darks menu and select Dark Library it'll bring up a Dark Library Creation dialog.


Doh,I did not know that..:( It still does not explain the issues I experienced in DEC guiding though. That was corrected immediately when switching back to PHD2 v2.2a.

I will try it again on a clear night, maybe it was just a fluke, but others have reported similar issues with DEC guiding.

Thanks for that info,

Paul
 

#875 Astronewb

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Posted 13 July 2014 - 11:45 AM

What tazer said... No trouble producing and using a darks library in PHD2 v2.3

Paul, what is the focal length of your guiding optics?


I use a QHY5L-II with a Borg 50mm achro, the focal length is 250mm.

Cheers...Paul
 






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