#21  
Old 15-07-2019, 09:03 PM
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lazjen (Chris)
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Originally Posted by benklerk View Post
I just ordered the CEM120EC with the RA encoder. Ordered it though Sidereal Trading so I have full Australian warranty on the mount. I should have it in about 3 weeks. I also got 4 counterweights and the permanent pier.

This is going along with all new gear, including a 14" RC with a G4-16000 camera with filters.

Cant wait to set everything up.
Nice.

I'll be ordering more counterweights later on when I load up my mount with a side by side setup and put at least 2 scopes on there (RC10 + Sharpstar 107PH and maybe the Coronado as well).

I got mine through Telescopes and Astronomy, so I also have Australian warranty/consumer protection.
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  #22  
Old 28-07-2019, 02:30 PM
ghealey56 (Geoff)
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Originally Posted by benklerk View Post
I just ordered the CEM120EC with the RA encoder. Ordered it though Sidereal Trading so I have full Australian warranty on the mount. I should have it in about 3 weeks. I also got 4 counterweights and the permanent pier.

This is going along with all new gear, including a 14" RC with a G4-16000 camera with filters.

Cant wait to set everything up.

Ben
I have ordered a CEM60EC also through Paul Litchen at Sidereal Trading. Terrific services and I gather there are a few of us filled with iOptron anticipation!
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  #23  
Old 14-08-2019, 09:09 AM
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Time for an update. I've had other things on my plate for a bit besides this hobby, so time has been an issue.

However, shortly after my last update, I got the mount on to the pier in the dome and loaded up the counterweights. Then to my shock, I discovered I could not get the RC10 or my other dovetail (for the refractor) on to the mount's saddle plate. I was very annoyed that I had not checked this beforehand while it was in the house, but it just did not occur to me that it would be an issue.

To cut a very long story short, I now have a replacement mount saddle plate that I received yesterday. My RC10 now fits it quite snugly. The other plate slides in/out much easier.

I held off on an update until this was resolved to ensure the full picture can be presented - overall support with iOptron has been good/ok given it's via email and massive time zone differences (they're in US east coast). It took nearly a month to sort out as I had to post the saddle plate to them first before they would send a replacement. I can understand this process, but it's still frustrating.

So, what was the issue you might be thinking? There's specs for what a losmandy dovertail should be, and theoretically there's also specs for the mount saddle plate too (as provided by iOptron). I hit the "perfect" combo of my dovetail plates being slightly over spec and the mount saddle plate slightly under spec. There's 2 significant measurements here - the narrow and large widths. For my problem it was the narrow width that caused the grief.

So while I was not "blameless" for this problem given the out of spec dovetails, iOptron really had the greater fault in not ensuring the mount saddle plate was correct spec. If they were at perfect spec, my dovetails would have worked, albeit with tight margins. Also, I personally believe their mount saddle plate is inferior to what I've used on the G11.

However, it should be noted that iOptron has come through and sorted out the problem for me.

I'm hoping I can do more with it tonight, weather permitting - and if we can get my dome rotation going again.
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  #24  
Old 15-08-2019, 12:09 PM
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I did manage to do some more work on the setup yesterday/last night.

With all the time passing, I've become a little impatient, so I decided to put the RC10 on for the largest FL I've got to really test things out (so no FR, just the "vanilla" 2000mm F8 setup). I may need to collimate the scope, so this setup may change to my refractor depending on how that goes.

The first thing I discovered was that balancing the CEM seemed to be a little bit more tricky than the GEM. Part of this was related to only having 2 counterweights and the back heaviness of the RC10. Getting the RA balance close was not too difficult, but I had to adjust it if I made changes to get the DEC balance sorted (when shifting weight as well as the obvious add/remove weight).

The DEC balance was more difficult because of the saddle plate locking knobs. I wanted to ensure all 3 were used to grabbed the dovetail, so the RC10 was sitting back further than what I used to have on the G11. To sort out the lack of weight on the front, I found that using my solar scope mounted on the top rail did the trick - which is handy because I was planning to mount it there anyway.

Wiring up the mount is great now. I connect to the mount via ethernet, so that's one less cable to the computer. I also connect to the USB3 on the mount, and have wired up the camera, fw and guide cam to that. I'll be adding the focuser to that as well, but it means I have just one direct connection from mount to PC - USB3.

Not content with just changing one thing, I messed with a few other things, including the OAG I was using, a tilt adjuster, the spacing between the camera and the filter wheel, etc. This meant that it took me a while to sort out the correct backfocus. It didn't help when the guide camera got chosen instead of the main camera when I was trying to check things. It confused me until I realised what was happening and sorted it out.

Eventually I got a very rough focus in place and noticed the PA was quite whacked (well having done no PA so far, probably not a surprise. ). My dome still can't rotate, so I had a fixed opening to try to sort it out. I spent a bit of time trying to get it better, but I was still getting drift in one direction. I ran out of time to do any more (and I was getting tired), so I hope to continue tonight. I'll go back to basics and work it out from scratch.

I am starting to get used to the idiosyncrasies of the mount hand controller and the Commander software. There's a few things in each I would do differently (just like for the G11), but nothing that's completely broken. Probably the most annoying thing is having to power cycle the mount if you park using the hand controller. The Commander software allows you to unpark. Just the usual type of weirdness one gets with astro gear/software.
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  #25  
Old 19-08-2019, 09:49 PM
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lazjen (Chris)
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I've had a few hours over the last few nights to proceed further. I at least now have manual dome rotation so I can get to anywhere I want.

After much stuffing around, I came to the conclusion that I couldn't get the PA sorted using PHD drift align with the out of collimation RC10. I also discounted using the methods in the hand controller to do PA once I realised that I had no idea how to work out what dots on the screen were what stars it was asking for, even if they didn't all look like comets.

So, I've switched to the Sharpstar 107PH until I sort out the RC10, so testing at 700mm instead of 2000mm. Although I still managed to stuff around getting it done, it was of a lesser quantity.

I got the PA to 1.6' for the night using PHD Drift Align - I'll refine it more another time. Also, I need to experiment more with the PHD settings to find the most ideal setup.

I took a 10 min Ha exposure of M16 for a test. I then discovered I had some terrible tilt in the system:

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I took 2 more images with similar results. For the first 2 I used 6 sec guiding (because that was the max I had in the dark library at the time). For the 3rd image, I used 10 sec guiding after creating the missing darks. I forgot to keep the PHD logs, but the guiding seemed "mostly fine", as in if I improved PA and tweaked the settings I could probably do much better.

I think I know what's causing the tilt (OAG is biggest suspect) and the next night I'm out I'll be trying to sort that out. If it wasn't for the tilt and some dodgy focus because of it, the 3 images I took would have been ok-ish.

I'd like to do a longer exposure for a test, but even at 0 gain, the ASI1600 was saturating parts of M16. I'll have to do a fainter/darker area to see how that goes sometime.
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  #26  
Old 20-08-2019, 11:00 PM
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Ok, tilt was related to the OAG - a bit, but the major culprit was user error - I forgot to put the field flattener on. That made a bit of a difference.

Unfortunately, still not there yet as I have to adjust the back focus. The Celestron OAG I am trying out is using up too much of the back focus. I suspect I will need to go back to the TS OAG to make it all fit correctly.

I'm taking a few shots of M16 now, mostly to see how the tracking goes over a longer time.
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  #27  
Old 21-08-2019, 03:51 PM
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Here's some guiding graphs from last night while I was taking 10min exposures of M16. I was using 5 sec guiding. I lost the star some time after the 2nd pic below - I haven't checked the results of all the exposures yet.

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Beforehand I tried to improve the PA further. Adjusting the altitude was a lot more finicky than the azimuth and I think I will need to do a bit more there. Also, I'm not sure what the best DEC guiding algorithm to use - for this I used the resist switch.

However, overall I was fairly happy with the guiding results.
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  #28  
Old 21-08-2019, 05:24 PM
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Thank you for sharing your guiding graphs Chris. RA looks really nice, I think DEC could be improved by lowering aggressiveness, because it goes up and down and corrections should be in one direction only? I would lower DEC aggressiveness to say 0.50-0.70 for a start, maybe even relax min movement to 0.25 in DEC? But it looks like the PA was a bit off?



Overall pretty nice consistent guiding graphs
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  #29  
Old 21-08-2019, 06:08 PM
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Originally Posted by Slawomir View Post
Thank you for sharing your guiding graphs Chris. RA looks really nice, I think DEC could be improved by lowering aggressiveness, because it goes up and down and corrections should be in one direction only? I would lower DEC aggressiveness to say 0.50-0.70 for a start, maybe even relax min movement to 0.25 in DEC? But it looks like the PA was a bit off?



Overall pretty nice consistent guiding graphs
Yes, I need to work out what the best setting is for PHD for this mount - it's very different to the G11.

I agree the PA is a bit off - that ALT was not easy to adjust. It's unlock 2 hex bolts, then adjust the knob which has a lot of play in it, then tighten up and test again. I think it's only the ALT that I really need to adjust now.

I'll sort the PA out before I mess around with PHD guiding again. And I'll consult some other CEM120EC2 owners about their thoughts on the DEC algorithm/settings to use. I do agree that the DEC seemed to react too aggressively.
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  #30  
Old 21-08-2019, 06:43 PM
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M16 Ha, 9 x 10 min, ASI1600MM-C at Gain 0, Offset 10, dark calibrated, cosmetic correction, dizzle integration (@ x2). Only resized back down to "normal" frame size, no cropping, just jpeg compression at 70% to fit forum size. So, you can pixel peep to see the main problem with it...

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..which is shown nicely in these images:

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The stars seem to point in to the centre, so I believe this means I need more space between the field flattener and the CCD. If so, that's a pleasant surprise since I had thought the reverse and was starting to puzzle as to what I could remove.
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  #31  
Old 24-08-2019, 11:45 PM
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I've done some more refinement on the PA and adjusted the image train to reduce some of the eccentricity issues. Both are not perfect, but I thought I'd see how some guiding would go:

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Note the display scale has changed to +- 2". I also changed the DEC algorithm to LowPass2 and took the settings as suggested by the guiding assistant.
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  #32  
Old 25-08-2019, 06:51 AM
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Hi Chris,

Since dithering is included in the calculation of total rms error, I reckon the mount guides very nicely

With my new laptop I was getting a bit of random noise in some of guide frames and this random subtle noise was enough to move the starís centroid - selecting an option in PHD2 for using subframes only has lowered traffic through that USB cable and fixed random noise issue and guiding graph got much smoother.
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  #33  
Old 25-08-2019, 08:44 AM
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Originally Posted by Slawomir View Post
Since dithering is included in the calculation of total rms error, I reckon the mount guides very nicely
I didn't know that, so that's good to hear. I was dithering after every image, since they were 10 min exposures. As I was cycling through LRGB last night, I could have done once every 4 images, but I did bother - it's fairly quick and painless.

Also, I think I could go much longer on my image exposures without issue - the camera is the main limitation now. So, that's good for any future camera changes.

Quote:
Originally Posted by Slawomir View Post
With my new laptop I was getting a bit of random noise in some of guide frames and this random subtle noise was enough to move the starís centroid - selecting an option in PHD2 for using subframes only has lowered traffic through that USB cable and fixed random noise issue and guiding graph got much smoother.
I thought I had that option set, but the screenshot shows it's definitely not there. Weird.
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  #34  
Old 25-08-2019, 08:45 AM
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Here's a snapshot of the graph after nearly 2.5hrs of continuous guiding:

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  #35  
Old 26-08-2019, 05:30 PM
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I got my new CEM120EC today. Looks nice, can't wait to install it and try out my RC 14 on it.

As I'm still building my Obs, it will be a few more weeks until I test it.

Ben
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  #36  
Old 26-08-2019, 05:36 PM
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Originally Posted by benklerk View Post
I got my new CEM120EC today. Looks nice, can't wait to install it and try out my RC 14 on it.

As I'm still building my Obs, it will be a few more weeks until I test it.
Take the opportunity to get to know the mount before it goes into the dome. Read the manual and understand how the various knobs are supposed to work and the combinations for the lock/gear engage, etc.

Also, check out what you can - for example, check the saddle mount plate is in spec and your dovetail(s) fit (assuming they are spec as well).

There's a site dedicated to the CEM users you might like to look at as well - includes a lot of discussion on the various firmware releases, etc. https://www.cem-mount-user.tech/index.php
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  #37  
Old 31-08-2019, 11:16 PM
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Finally the weather has cleared after a week of clouds and rain.

Tonight I'm trying 15 sec guiding exposures and switching to the King rate. For the target I'm on I really don't need 15 sec, but I might need it in the future when I'm using the RC10.

So far, it's going well. I've got PHD2 Log Viewer now, so I hope to post some details from that.
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  #38  
Old 01-09-2019, 07:31 PM
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Quote:
Originally Posted by Slawomir View Post
With my new laptop I was getting a bit of random noise in some of guide frames and this random subtle noise was enough to move the starís centroid - selecting an option in PHD2 for using subframes only has lowered traffic through that USB cable and fixed random noise issue and guiding graph got much smoother.
On this point, I'm getting something weird happening in PHD2. I haven't tracked down the cause, but it sometimes loses the plot completely when choosing the subframe - it comes in all white and loses the star. So PHD2 then flips back to full field, find the star again, goes back into subframes and the cycle continues. If I leave it full frame, it's happy.
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  #39  
Old 01-09-2019, 07:38 PM
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Some guiding graphs from last night. I switched to 15 sec guiding exposures, and part way through the first graph, I changed to King tracking rate.

This one west pier side (so scope pointing east):

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And this is east pier side. The extra long dither in the middle was me finally remembering to check the focus. I have temp compensation on and the focusing didn't seem to adjust much at all, so that was good.

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Unless I discover anything more, I'll probably wait until I can get my RC10 on for further reports. So far this is a very nice mount and I'm quite happy how it's performing so far.
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  #40  
Old 03-09-2019, 08:36 AM
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Bit of a update on my mount.

The saddle plate is fine. Telescope saddle plate easily slides in.

There is a bit of movement in the DEC, might need to tighten it up. Don't know if its because no weight is on it. But I would expect very little movement when its in the locked position.
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