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New iOptron CEM70G Questions

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#1 phileefan

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Posted 25 July 2021 - 08:10 PM

Hello all,

 

Just recently bought a iOptron CEM70G mount and haven't had any opportunities to use it due to the weather. 

 

This is the 1st iOptron mount I've owned and I'm curious what current owners alignment procedure is. 

I don't any DSO just planetary. 

 

Any help is appreciated. Thanks.................... 



#2 Woody218

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Posted 26 July 2021 - 09:52 AM

I use Sharpcap to polar align, then go to whatever I'm going to image. Sharpcap will connect to the ipolar camera with no issues.



#3 phileefan

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Posted 26 July 2021 - 03:13 PM

I use Sharpcap to polar align, then go to whatever I'm going to image. Sharpcap will connect to the ipolar camera with no issues.

So that's all you do? No 3 star alignment????


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#4 Blackhawk163

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Posted 26 July 2021 - 05:06 PM

So that's all you do? No 3 star alignment????


that's all you do. As long as your ipolar camera works that is 😒

#5 phileefan

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Posted 26 July 2021 - 05:14 PM

that's all you do. As long as your ipolar camera works that is

Well, I've yet to get outside under the stars with it yet, but on the bench I tried it out and it seemed to be fine. Well see........ Thanks!



#6 MikeCrapo

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Posted 26 July 2021 - 06:12 PM

I only do a polar alignment as well. Seems to me the 3 star alignment is if you can’t do a polar alignment and need a different way to setup alignment.



#7 phileefan

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Posted 26 July 2021 - 06:53 PM

I only do a polar alignment as well. Seems to me the 3 star alignment is if you can’t do a polar alignment and need a different way to setup alignment.

MikeCrapo,

 

Thanks for your response. I guess I always assumed that star alignment also needed to be done in addition to polar alignment! Thanks...



#8 rgsalinger

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Posted 26 July 2021 - 07:01 PM

The three star calibration is not really a substitute for polar alignment. The three star is to get rid of things like cone error and/or mirror flop is using an SCT. It makes slews more accurate. Polar alignment eliminates field rotation problems and makes guiding easier becauser the DEC axis has to move only infrequently. First get the PA done and then do the three star is what is generally done.

 

However, if you are taking really short exposures, you will never see field rotation but the tracking will be poor (may or may not matter). You may find that just a rough polar alignment will suffice. That will not suffice for long guided exposures. 

 

Rgrds-Ross



#9 phileefan

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Posted 26 July 2021 - 07:43 PM

The three star calibration is not really a substitute for polar alignment. The three star is to get rid of things like cone error and/or mirror flop is using an SCT. It makes slews more accurate. Polar alignment eliminates field rotation problems and makes guiding easier becauser the DEC axis has to move only infrequently. First get the PA done and then do the three star is what is generally done.

 

However, if you are taking really short exposures, you will never see field rotation but the tracking will be poor (may or may not matter). You may find that just a rough polar alignment will suffice. That will not suffice for long guided exposures. 

 

Rgrds-Ross

Ross,

 

Thanks for the response. I'm not doing any DSO, just planetary. Like I commented above, I was under the assumption I needed to do some sort of star alignment so that when I would slew to say Jupiter, it would get it on the sensor of my camera chip. confused1.gif



#10 rgsalinger

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Posted 26 July 2021 - 09:39 PM

If that were my mount I would polar align and do a three star calibration. I don't know what software you are using but the key to happy imaging is learning about plate solving rather than worrying too much about doing multip star calibrations. 

Rgrds-Ross


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#11 phileefan

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Posted 26 July 2021 - 11:52 PM

If that were my mount I would polar align and do a three star calibration. I don't know what software you are using but the key to happy imaging is learning about plate solving rather than worrying too much about doing multip star calibrations.
Rgrds-Ross

In your opinion, what is a good plate solving software??

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#12 Orion64

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Posted 26 July 2021 - 11:55 PM

At this stage I'm doing the ipolar thing, which is really sweet, and then check with PhD drift align, for at least 8min. Normally very close to perfect.
Then just a one star align, you'll be surprised how close the mount gets. But I would suggest 3star alignment, it'll get you basically spot on, I'm coming from a cgem and the difference in improvement is day and night

#13 Orion64

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Posted 26 July 2021 - 11:57 PM

My only concern at this stage is that I cannot get below 1arcsec per pixel guiding, but I'm assuming this may be seeing, hopefully I'll see improvements in the coming weeks.
But this is probably beyond the scope of your opening question

#14 OldManSky

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Posted 27 July 2021 - 08:15 AM

Like many others, no star alignment here.  Not with my current CEM60 and previous CEM25P.

The CEM60 is on a pier, so permanently polar aligned...but the procedure was the same when I polar aligned every night just minus the non-iPolar alignment routine:

 

Slew to a star, plate solve, recenter, and sync.  Done.  No star alignment.

 

Other than the first couple of months with my CEM25P, I don't think I've done a star alignment in 3 years.  I honestly haven't ever done one with the CEM60 mount :)

 

I use NINA for control and ASTAP for plate solving. 1-2 seconds tops to solve.



#15 phileefan

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Posted 27 July 2021 - 08:16 AM

At this stage I'm doing the ipolar thing, which is really sweet, and then check with PhD drift align, for at least 8min. Normally very close to perfect.
Then just a one star align, you'll be surprised how close the mount gets. But I would suggest 3star alignment, it'll get you basically spot on, I'm coming from a cgem and the difference in improvement is day and night

Thanks for your reply! I will try what you suggested. I'm moving up from a CGEM so I'm excited to see the difference.....

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#16 phileefan

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Posted 27 July 2021 - 08:20 AM

Like many others, no star alignment here. Not with my current CEM60 and previous CEM25P.
The CEM60 is on a pier, so permanently polar aligned...but the procedure was the same when I polar aligned every night just minus the non-iPolar alignment routine:

Slew to a star, plate solve, recenter, and sync. Done. No star alignment.

Other than the first couple of months with my CEM25P, I don't think I've done a star alignment in 3 years. I honestly haven't ever done one with the CEM60 mount :)

I use NINA for control and ASTAP for plate solving. 1-2 seconds tops to solve.

Thanks OldManSky! Your response answered all my questions. I was wondering what folks were using for their plate solving. I will check it out.

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#17 limeyx

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Posted 27 July 2021 - 10:25 AM

I only do a polar alignment as well. Seems to me the 3 star alignment is if you can’t do a polar alignment and need a different way to setup alignment.

3-star alignment is for GOTO accuracy, not tracking, right ?

 

- Do PA

- Plate solve & Sync the mount (most sequencing / capture software will do this)

 

-> No need for any star alignment


Edited by limeyx, 27 July 2021 - 10:25 AM.


#18 phileefan

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Posted 27 July 2021 - 11:51 AM

3-star alignment is for GOTO accuracy, not tracking, right ?

- Do PA
- Plate solve & Sync the mount (most sequencing / capture software will do this)

-> No need for any star alignment

Yes I'm looking for GOTO accuracy.... Thank you!

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#19 rgsalinger

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Posted 27 July 2021 - 12:29 PM

"1arcsec per pixel guiding" is an odd turn of phrase. What I think you mean is that your guiding RMS error (both axes) runs just a bit over 1 arc second. Whether that's good enough depends on your image scale and focal length mostly. Of course with poor seeing, that value will be quite high and your raw data will have larger stars.

 

Rgrds-Ross



#20 DuncanM

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Posted 27 July 2021 - 01:47 PM

In your opinion, what is a good plate solving software??

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I have a CEM120 and CEM60 that are on permanent piers. I have never done any star alignments.  I PAed with Sharpcap.  I start the mount at the zero position, slew to my first target's expected location, plate solve and then slew to the actual target location with repeated ~15 arc sec accuracy.

 

I use the built-in (stand alone) plate solve engine in Astroart 7 (AA7), which incorporates plate solve assisted gotos into it's telescope and camera control interface.

 

AA7 also incorporates a star chart (with a solar system database) into the program and you can use that to locate your target, check RA/DEC, Alt/AZ rise/set, etc and then use it to initiate a goto or add the target to your target list.



#21 rgsalinger

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Posted 27 July 2021 - 02:57 PM

The better question is to ask what image acquisition software is best to use. Platesolving followed by precision slewing to the target is supported by a wide range of products. You should do some research and select one that makes sense for you. Personally, I use the SKYX since it came with my mounts and pretty much did what I needed. I augmented it with CCD Autopilot to be able to hit multiple targets each night and to have reliable automated merdian flips. That's an expensive solution but it was what was around 6 or so years ago. 

 

Rgrds-Ross


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