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iOptron CEM60 - how to set the Zero point

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#1 WConde

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Posted 25 March 2018 - 03:16 PM

Hello everyone! After many months researching and pondering several options, I am about to press the “buy” button to purchase an iOptron CEM60. The only concern that I have with this mount is how to setup the Zero Point correctly. I’ve noticed this is a crucial step for the mount to accurately center objects in the camera view, but reading threads in several forums (Cloudy Nights included) it is also the thing that most first time users struggle with. I’ve noticed that there’s even people who never were able to nail this down successfully!! I’ve read the CEM 60 owners manual but I think the instructions on how to set the Zero point are quite vague. I’ve also read several threads about this issue but honestly the exchanges have confused me even more. Some people seem to use Polaris to setup the Zero point while others simply put the mount roughly pointing to the North, others seem to use levels... I’ve also watched Paul Chase’s tutorial, which is more clear but based on an EQ25. If any of you who own a CEM60 and have successfully setup your Zero point could share the steps you followed with me I will be more than grateful!!


Edited by WConde, 25 March 2018 - 03:18 PM.


#2 Salacious B Crumb

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Posted 25 March 2018 - 04:10 PM

I don't know crucial this is really. I used a level to mark mine. If you use a program like SG Pro, you Polar align and make sure your mount's memory is cleared when it comes to any alignment settings. 

 

- Mikko



#3 leveye

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Posted 25 March 2018 - 04:27 PM

While I have never owned the CEM60 I have owned ZEQ25GT and did a very accurate manual drift alignment of the mount first using PHD and then just turned the mount off in this position and marked it making it the "home/parked" position ala Paul Chasse method. Granted I never moved my tripod afterwards so this worked really well for me from session to session.


Edited by leveye, 25 March 2018 - 04:28 PM.


#4 rgsalinger

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Posted 25 March 2018 - 11:18 PM

If you are using MaximDL then you will center things by using PinPoint rather than worrying about accurate goto's. Just fire up the mount, polar align it, focus on anything and then issue a go to your target. You then use the analyze tab to get the correct center of the image, sync and slew. MDL latest versions have automated slew refinement to accomplish this. This technique works if the object is withing the FOV of the camera 100 percent of the time. In the event that the scope is pointing so far off that the object is not in the FOV, then (if you have an internet connection) send a binned image via MDL to astrometry.net and get a solve from there. I use my phone tethered to my PC when I don't have wifi to accomplish this.

 

Now this is not the same as polar alignment. This is about pointing after polar alignment. So, I'm not seeing how being compulsive about the zero point matters much if you have an up to date copy of MaximDL.

 

Rgrds-Ross


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#5 ThomasLight

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Posted 26 March 2018 - 06:57 AM

I am only a few months into this hobby, so excuse my ignorance. I have a Ioptron CEM25P. My understanding is that the Zero position is for accurate reference fo the GoTo electronics. The manual instructions suggest how the scope should be orientated, as "starting" position only. I just might be very wrong and if so sorry to muddy the sharing here. This weekend I was with a fellow "expert" and his treatment of Zero position was also nominal, he did not worry too much. Thank you all, Tom



#6 Real14

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Posted 26 March 2018 - 10:15 AM

 

I’ve noticed this is a crucial step for the mount to accurately center objects in the camera view,

Hi WConde,

This is not exclusive for iOptron mounts. Not all ? but many mounts need that position to know where they are when they start = Local Meridian Time

Zero Position is counterweight shaft vertical and DEC axis horizontal. That is it. On my G11 I glued a level on the DEC axis in order to know when it is horizontal ...

 

zero_level.jpg



#7 rgsalinger

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Posted 26 March 2018 - 10:32 AM

I'm not sure where you could put a level on the CEM60 to accomplish that, but it's sure a good idea. However, the OP's issue is to "accurately center objects in the camera view". So, I continue to say that centering objects is best handled by the imaging software's plate solving function. Before plate solving came into being, it was really crucial to get everything just right. Cameras back then had small chips. The combination made imaging much harder than it is today. The zero point becomes critical once you want to do visual observing with a long focal length scope.


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#8 Real14

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Posted 26 March 2018 - 10:42 AM

I'm not sure where you could put a level on the CEM60 to accomplish that, but it's sure a good idea. However, the OP's issue is to "accurately center objects in the camera view". So, I continue to say that centering objects is best handled by the imaging software's plate solving function. Before plate solving came into being, it was really crucial to get everything just right. Cameras back then had small chips. The combination made imaging much harder than it is today. The zero point becomes critical once you want to do visual observing with a long focal length scope.

Right. I have never ever used  Plate solving in my life because honestly I never understood it and the way I have been imaging was never automated in that way.

 

You can also put the level on the dovetail plate or any surface which is horizontal to the ground at the DEC assembly.

 

A good alignment model also puts the objects in center.

 

I think I will have to take a look into plate solving.

 

May I ask what programs do you need for that ?

 

Thanks waytogo.gif


Edited by Real14, 26 March 2018 - 10:43 AM.


#9 bmhjr

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Posted 26 March 2018 - 11:00 AM

On the CEM60, the zero position is counterweight down with DEC as shown in the picture. You can set it two ways.

 

1) There is a permanent factory zero position.  You can roatate the RA horizontal and then from the handcontroller or Commander interface do a "search for zero".  It will go to the factory zero and stop.  You can then enter "set zero to current position"

 

2) Level the tripod, point counterweights down and DEC veritcal using a level if you wish.  The enter ""set zero to current position".  This will now be the new zero position.

 

As mentioned, this is only needed for accurate goto and alignment.  I dont ever worry about it. I just set up and then use platesolving to find the target without ever doing an alignment.

 

 

cem60.jpg

 


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#10 Real14

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Posted 26 March 2018 - 11:18 AM

Hi,

 

One of my G11 are at my home right now and Tomorrow the buyer will visit me so I can give him an introduction.

 

Just took this images. Look at the different positions you can put a level. With a little bit of imagination you can make yourself an adapter of cardboard and place it on similar edges. 

 

IMG_2961_C1_CN.jpg IMG_2959_C1_CN.jpg IMG_2960_C1_CN.jpg


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#11 rgsalinger

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Posted 26 March 2018 - 11:22 AM

Right now I would recommend using Sequence Generator Pro. That program which costs less than 200 dollars uses Platesolve2 which is a platesolving program written by Dave Rowe. I use the same software on a 25" RC at almost 5 meters. Objects are dead center every time. The OP has MaximDL. Most of the latest versions of that software come with Pinpoint LE written by Bob Denny. It works almost as well but has trouble with "blind" platesolves and/or images that are way far away from where the mount thinks that it is. Plate solving will make life much easier.

 

I'm just now transitioning from my Atlas AZ/EQ6 mount. I could almost never get objects in the camera FOV as there was really no easy way to get to an accurate zero position. Instead, I just set it to be approximately correct, slew and platesolve. That refines the pointing and I find with just that one point I'm good for the night.


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#12 WConde

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Posted 26 March 2018 - 04:04 PM

On the CEM60, the zero position is counterweight down with DEC as shown in the picture. You can set it two ways.

 

1) There is a permanent factory zero position.  You can roatate the RA horizontal and then from the handcontroller or Commander interface do a "search for zero".  It will go to the factory zero and stop.  You can then enter "set zero to current position"

 

2) Level the tripod, point counterweights down and DEC veritcal using a level if you wish.  The enter ""set zero to current position".  This will now be the new zero position.

 

As mentioned, this is only needed for accurate goto and alignment.  I dont ever worry about it. I just set up and then use platesolving to find the target without ever doing an alignment.

 

 

attachicon.gif cem60.jpg

That is exactly what I want. Right now the only thing that I like about my AVX is that objects fall right in the center of my FOV without having to do any plate solve of any kind. I guess now that I want to “grow” I will have to learn how to do that. Can you point me to a good tutorial or webpage where I could learn how to do that? Right now I use an old Maxim DL license which I don’t even know if it is capable of plate solving. Most likely I will switch to SGP once I get my new mount.


Edited by WConde, 26 March 2018 - 04:17 PM.


#13 WConde

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Posted 26 March 2018 - 04:15 PM

While I have never owned the CEM60 I have owned ZEQ25GT and did a very accurate manual drift alignment of the mount first using PHD and then just turned the mount off in this position and marked it making it the "home/parked" position ala Paul Chasse method. Granted I never moved my tripod afterwards so this worked really well for me from session to session.

I have to confess that I’d never done a drift alignment.  This is in part because it is time consuming and my imaging time is quite limited.  Do you think I can do a Polar alignment with my Pole Master and then mark the Zero Point using Paul Chase method?



#14 WConde

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Posted 26 March 2018 - 04:26 PM

If you are using MaximDL then you will center things by using PinPoint rather than worrying about accurate goto's. Just fire up the mount, polar align it, focus on anything and then issue a go to your target. You then use the analyze tab to get the correct center of the image, sync and slew. MDL latest versions have automated slew refinement to accomplish this. This technique works if the object is withing the FOV of the camera 100 percent of the time. In the event that the scope is pointing so far off that the object is not in the FOV, then (if you have an internet connection) send a binned image via MDL to astrometry.net and get a solve from there. I use my phone tethered to my PC when I don't have wifi to accomplish this.

 

Now this is not the same as polar alignment. This is about pointing after polar alignment. So, I'm not seeing how being compulsive about the zero point matters much if you have an up to date copy of MaximDL.

 

Rgrds-Ross

As I  told to  bmhjr,  the only thing that I like about my AVX is that objects fall right in the center of my FOV without having to do any plate solve of any kind. I guess now that I want to “grow” I will have to learn how to do that. Can you point me to a good tutorial or webpage where I could learn how to do that? Right now I use an old Maxim DL license which I don’t even know if it is capable of plate solving. Most likely I will switch to SG once I get the CEM60.



#15 WConde

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Posted 26 March 2018 - 04:44 PM

I don't know crucial this is really. I used a level to mark mine. If you use a program like SG Pro, you Polar align and make sure your mount's memory is cleared when it comes to any alignment settings. 

 

- Mikko

Well...based on what I’be read in other threads related to iOptron mounts’ performance, the thing that many people complain about is that iOptron’s GoTo do not bring the desired object to the FOV center and  the reason for that is not having set the Zero Point correctly.  My imaging time is very limited and honestly I want to make sure that the new mount’s GoTo function works properly since I don’t want to waste time  trying to center objects in my FOV.



#16 Salacious B Crumb

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Posted 26 March 2018 - 05:02 PM

WConde I think these are people who do visual not imaging. If you don't use any other programs, your zero position and star alignment after are important for your GoTo. That was one of the things which confused me also at the beginning and my problems disappeared when I understood to clear all my mount alignments. But like others have said here, if you image you'll probably end up using a plate solving program and it does the centering and the whole 9 yards for you.

 

BTW I have never done a drift alignment either, I just use PoleMaster and I'm imaging in a couple of minutes. I have marks on the concrete and typically my PoleMaster adjustment is just a minor nudge to one of the tri-pier legs to "fine-tune" the alignment.

 

 

Hope this helps,

 

Mikko


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#17 rgsalinger

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Posted 26 March 2018 - 05:55 PM

There is no mount made that will bring objects to the center based on just setting the zero point accurately. Having the time off by 4 seconds will put the first go to 1 arc minute off. I own a Paramount MX+ and have essentially perfect polar alignment. It possesses homing sensors so it knows EXACTLY where it is when it's ready to image. Yet go to's can be off by as much as three arc minutes before calibration. If I were using a very short refractor, it would look like things were centered. When people report that things are perfectly centered without doing a considerable amount of calibration (multi stars) or using plate solving, I just don't believe them.

 

If you have a MaximDL release that less than 8 years old then you have plate solving. Read the manual, it's not hard at all to do. The two things you have to are to download the guide star catalog and make sure that your optics are correctly described in the settings panel. The rest is automatic.

 

Rgrds-Ross



#18 WConde

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Posted 26 March 2018 - 07:20 PM

There is no mount made that will bring objects to the center based on just setting the zero point accurately. Having the time off by 4 seconds will put the first go to 1 arc minute off. I own a Paramount MX+ and have essentially perfect polar alignment. It possesses homing sensors so it knows EXACTLY where it is when it's ready to image. Yet go to's can be off by as much as three arc minutes before calibration. If I were using a very short refractor, it would look like things were centered. When people report that things are perfectly centered without doing a considerable amount of calibration (multi stars) or using plate solving, I just don't believe them.

 

If you have a MaximDL release that less than 8 years old then you have plate solving. Read the manual, it's not hard at all to do. The two things you have to are to download the guide star catalog and make sure that your optics are correctly described in the settings panel. The rest is automatic.

 

Rgrds-Ross

Maybe I was not clear when I said that with my AVX the objects come right to the center since that is after I do Polar alignment with the Pole Master and calibrate with 6 stars.  The reality is that once I am done with the polar alignment and the calibration  and I slew to the object I want to image, it comes very, very close to the center of my FOV....to the point that I can image the same object for a few nights in a row and I barely need to crop the stacked image because of stacking artifacts.  That is the ONLY thing that I like about my AVX and I would like to replicate with the new mount.  With the AVX I don’t need to care about setting the Zero point because the mount comes with those marks.  Setting a Zero point will be new for me and I want to make sure that I do it correctly.

 

The Maxim versión that I use is about 4-5 years old.  I will look for the instructions for plate solving in the manual.  

 

Many thanks!



#19 ImNewHere

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Posted 26 March 2018 - 07:43 PM

I simply used a marker to mark mine on the SmartEQ Pro, ZEQ25, and IEQ45, and after leveling the mount, doing a PA according to what the hand controller says, and a 1 star alignment I'm pretty good.



#20 bobzeq25

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Posted 27 March 2018 - 12:03 AM

Hello everyone! After many months researching and pondering several options, I am about to press the “buy” button to purchase an iOptron CEM60. The only concern that I have with this mount is how to setup the Zero Point correctly. I’ve noticed this is a crucial step for the mount to accurately center objects in the camera view, but reading threads in several forums (Cloudy Nights included) it is also the thing that most first time users struggle with. I’ve noticed that there’s even people who never were able to nail this down successfully!! I’ve read the CEM 60 owners manual but I think the instructions on how to set the Zero point are quite vague. I’ve also read several threads about this issue but honestly the exchanges have confused me even more. Some people seem to use Polaris to setup the Zero point while others simply put the mount roughly pointing to the North, others seem to use levels... I’ve also watched Paul Chase’s tutorial, which is more clear but based on an EQ25. If any of you who own a CEM60 and have successfully setup your Zero point could share the steps you followed with me I will be more than grateful!!

I do the following.

Set the zero point by eye. For RA, you can go parallel with an obvious straight line. For DEC, you can align two screws.

Polar align very carefully with a PoleMaster. This is what's crucial, to get DEC tracking close (so autoguiding doesn't have to work very hard), and avoid field rotation during a subexposure. It's the one thing I can't do remotely.

"Sync to" a star near my target. Don't really care if the star is even in the field. Sometimes it is, sometimes not.

Take an image, platesolve (I use PlateSolve 2, computerized pattern recognition of the stars to say where you're pointed) to get exactly where I'm pointed at, correct the RA and DEC to the star. Take another image.

There it is. Center if necessary, hit enter to confirm the sync.

The mount is now clued in, further GOTOs work fine.

When I get to my target, I usually make some adjustments to frame the image. I wouldn't have wanted to center either object here.

https://www.astrobin...8597/B/?nc=user

I do all this remotely from my desk in the house, shortly I'll be using Sequence Generator Pro, which automates the process of getting on target via platesolving. You feed SGP the coordinates, it images, platesolves, corrects.

Basically platesolving has pretty much made GOTO accuracy almost moot. Level is also almost moot, you just don't want the scope to tip over. <smile>

For people who have not yet platesolved, it's nearly trivial. Doesn't require the night to learn. Download and install PlateSolve2, and either of the 2 associated catalogs. Free. Fire up PS2, load any image (it eats jpg and fit), enter the approximate RA and DEC, and the approximate field of view. Hit solve. The speed with which it works depends on how good your approximations were, it has to know where to start looking.

Edited by bobzeq25, 27 March 2018 - 12:22 AM.


#21 WConde

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Posted 27 March 2018 - 08:42 AM

“Sync to" a star near my target. Don't really care if the star is even in the field. Sometimes it is, sometimes not.

Take an image, platesolve (I use PlateSolve 2, computerized pattern recognition of the stars to say where you're pointed) to get exactly where I'm pointed at, correct the RA and DEC to the star. Take another image.

There it is. Center if necessary, hit enter to confirm the sync.

Thanks Bob for sharing your routine.  I will download Platesolve 2 to give it a try.  The part I don’t understand is when you say:  “correct the RA and DEC to the Star”.  Do you mean that I should enter the correct RA and DEC in the hand controller?  Which RA and DEC coordinates?  How do I make the mount slew to the right coordinates before I plate solve for the second time? My apologies if my questions sound dumb it is just that this is all new for me...



#22 bobzeq25

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Posted 27 March 2018 - 04:30 PM

Thanks Bob for sharing your routine.  I will download Platesolve 2 to give it a try.  The part I don’t understand is when you say:  “correct the RA and DEC to the Star”.  Do you mean that I should enter the correct RA and DEC in the hand controller?  Which RA and DEC coordinates?  How do I make the mount slew to the right coordinates before I plate solve for the second time? My apologies if my questions sound dumb it is just that this is all new for me...

You take the coordinates PS2 says you're pointed at, and the coordinates you want to be pointed at (if you've used the hand controller to GOTO a target, those will be specified as TRA and TDEC), and use either the hand controller or a computer (doesn't matter) to move the mount the difference. ie if you're 0 degrees 48 minutes too low, you move the mount that amount up.

The trickiest part in the whole deal is not moving the mount in the wrong direction. <smile> Watch the RA and DEC move, don't rely on the arrows.

There's never a need to apologize for any question at all.

Edited by bobzeq25, 27 March 2018 - 04:34 PM.


#23 HxPI

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Posted 29 March 2018 - 01:31 PM

I have a CEM60EC. Here is what I do to get the mount up and running:

 

- Level the Tri-pier before installing the mount

- Use Search for Zero to set zero position

- Use PoleMaster to polar align, which produces a very good polar alignment

- Verify GPS lat/long is good and sync date and time with the computer

- Never perform a sync or star alignment from the handset. Instead, I use SGP and have it do a plate solve before imaging. Takes only a minute to complete and works very well

 

Ciao,

Mel


Edited by HxPI, 29 March 2018 - 01:40 PM.

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#24 wsg89

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Posted 01 April 2018 - 03:41 PM

Hello all!  Total newbie here but having lots of fun and pretty good luck with my CEM60 and AT102 f/7.  I have no clue about plate solving or even auto guiding at this point but I'm getting 200sec subs and reasonably centered goto targets with the folowing routine:

 

- level the tripod with the mount installed

- level the mount as per Paul Chasse video

    This step seemed to correct my zero point as apposed to the factory zero point.  It seemed factory ZP was one gear space off to the east in the polar scope

- balance the payload

- turn on the mount and SET the zero point, do not goto or find

- Verify GPS settings, be aware of the dayllight savings time quirk

- Set the polar alignment using an separate app, the on board one is ok but not great

- do a 2 or 3 star alignment slewing to the center of FOV each time

- goto target

 

I don't move my mount much but I check me levels, and PA and then set my zero point every time.  I agree the iOptron instructions are very weak on the importance of setting the zero point.  Admittedly my FOV is very wide with my DSLR live view and I have know other reference point for scopes and mounts, but I am very pleased with the accuracy of my CEM60 goto.

 

SG


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#25 HxPI

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Posted 15 May 2018 - 12:41 AM

I have a CEM60EC. Here is what I do to get the mount up and running:

 

- Level the Tri-pier before installing the mount

- Use Search for Zero to set zero position

- Use PoleMaster to polar align, which produces a very good polar alignment

- Verify GPS lat/long is good and sync date and time with the computer

- Never perform a sync or star alignment from the handset. Instead, I use SGP and have it do a plate solve before imaging. Takes only a minute to complete and works very well

 

Ciao,

Mel

 

I was able to setup my equipment and perform some tests. Using my previous steps, there were some issues with tracking. After some research, I performed a solar system alignment on the handset. So after polar alignment, it appears an initial star or solar system alignment on the handset is REQUIRED for the mount to track properly. I’m not quite sure how subsequent sync commands after plate solving affects the mount!


Edited by HxPI, 15 May 2018 - 01:02 AM.



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