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Switching to iOptron: What I learned from my new GEM45

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#1 Michael Covington

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Posted 01 May 2021 - 05:39 AM

These are short notes on things I learned about using my new iOptron GEM45 equatorial mount, moving from Celestron mounts (AVX and CGEM). The CEM40 is very similar to the GEM45, and other iOptron mounts are also rather similar. I assume you have the instruction manual for your (actual or planned) iOptron mount; manuals are available on line.

Click here to view the article
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#2 zeddie

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Posted 01 May 2021 - 07:49 AM

Where in the menu is the "Search Zero Position" option? It's not with "Set Zero Position" or "Goto Zero Position" (at least not on my iEQ45 Pro). Does the iEQ45 Pro not have the internal index marks, or is it possible I need a firmware update? Also, I know you can add your own index marks, but how do you set it at the time you are going to add the index marks? Or, If you don't add the index marks, do you have a good way to set the zero position? I use an inclinometer, but I think that holding it against the counterweight bar is prone to error, and not the best solution. I use the inclinometer to set the counterweight bar parallel to the ground and then use the inclinometer to set the declination axis to my latitude. Then use the inclinometer to set the counterweight bar perpendicular to the ground. I feel like there must be a better way.

 

-Thanks


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#3 Billx

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Posted 01 May 2021 - 10:45 AM

Great article describing how iOptron mounts work.  I have the iEQ30 pro and can remember when the camera accidentally hit the tripod when slewing.  It made that awful noise and I thought I damaged it.  But it seemed to work fine afterward.  I am glad you verified how the gears work.  As in  the reply above, how do you search for zero, and does it matter where I set it as long as I set it when I set up, aiming close to Polaris.  I am using a Asiair to polar align and image.



#4 daveco2

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Posted 01 May 2021 - 07:28 PM

Excellent.  I went from an AVX to CEM40 and sure could have used this information at the time.  Nonetheless, thanks for clearing up some nagging questions.



#5 Michael Covington

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Posted 02 May 2021 - 10:58 PM

Where in the menu is the "Search Zero Position" option? It's not with "Set Zero Position" or "Goto Zero Position" (at least not on my iEQ45 Pro). Does the iEQ45 Pro not have the internal index marks, or is it possible I need a firmware update? Also, I know you can add your own index marks, but how do you set it at the time you are going to add the index marks? Or, If you don't add the index marks, do you have a good way to set the zero position? I use an inclinometer, but I think that holding it against the counterweight bar is prone to error, and not the best solution. I use the inclinometer to set the counterweight bar parallel to the ground and then use the inclinometer to set the declination axis to my latitude. Then use the inclinometer to set the counterweight bar perpendicular to the ground. I feel like there must be a better way.

 

-Thanks

2 things.

(1) I am getting reports that some mounts either do not have "Search Zero Position" in the menu, or report something like "Feature not available on this mount" if you choose it.  Apparently not all of them have the internal mechanical-photoelectric index.

(2) You can use bubble levels to find zero position.  Do it carefully and think through what you're doing -- make sure your level isn't free to move in some direction that throws it off.  Or set up the mount, star align, and then set the R.A. to 6 hours ahead of the current sidereal time and the declination to +90.  I think that will move the mount to zero position.  Then tell it to stop tracking.  I have not actually done it this way and would like to hear from anyone who has.



#6 Michael Covington

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Posted 02 May 2021 - 10:59 PM

From discussions in the iOptron group on Facebook I'm learning that there are a LOT of differences between model and model -- in fact there is apparently a "new" GEM45 that may not support "Search Zero Position" but I don't have precise details.

This comment section is a great place to accumulate information about such things.  Thanks in advance for all your contributions!


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#7 zeddie

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Posted 02 May 2021 - 11:35 PM

Hi Michael. It's pretty obvious how to set the RA axis to zero position using a bubble level, but how would you do the DEC axis?

 

Thanks.



#8 GOLundby

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Posted 03 May 2021 - 03:08 AM

From discussions in the iOptron group on Facebook I'm learning that there are a LOT of differences between model and model -- in fact there is apparently a "new" GEM45 that may not support "Search Zero Position" but I don't have precise details.

This comment section is a great place to accumulate information about such things.  Thanks in advance for all your contributions!

We need a short foot note describing the changes done to GEM45 recently. Basically they have simplified the production by delivering GEM45G without the built-in IGuide. The changes basically is in connectors where there is only one USB2 input placed at the end of the RA house together with a 2.5-5.5mm power in. This USB2 is internally connected to a USB2 hub with 3 clients; the Mount, the IPolar and the USB2 connector at the sadle. The Sadle is also changed and now contains the box where the IGuide scope would reside, making it much wider. It is now dual purpose with the "Vixen" clamp just below the "Losmandy" clamp. (If you have a short OTA and are using an Auto Focus device, this may conflict with and hit the box for IGuide.) The sadle has two outlets for power (2.1-5.5mm) and a guide port in the rear area and a USB2 port in front. There no more is a possibility to reconfigure the connectors from back to front to make room for own internal cabling.

 

As mentioned, there seems to be no seek Zero position implemented for this model. I guess that during setup as described, when you have counterweights on, if you let it swing freely the Zero for RA is where it stops (gravity). For the DEC I have so far just, in darkness, felt when the front edge is parallell with the DEC motor house. The locking of the worms engage then in the exact position.

 

The IPolar tricked me when setting up the first time. Before I got to make the RA rotation, it said "Finished" and displayed the cross for the axis (far down left) From then on my PA was always far off. To avoid this error, you must clear the values in setup, redo the operations but COVER THE IPOLAR until you have rotated about 90 degrees. If you really is obsessed by accuracy, you should redo this several times turning left and right and each time make a note of the axis coordinates, calculate average and use for the future.

 

That's about what I have so far after just having received the new GEM45. More later if I find something worth mentioning.


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#9 Michael Covington

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Posted 03 May 2021 - 09:21 AM

We do need some notes.  I can only write about the mount I actually have (a GEM45 with a low serial number) and am relying on the rest of you to gather the rest of the information.

As to how to use a bubble level to find zero position, I'd have to actually play with the mount a bit before saying.  It's tricky.  I wish iOptron would print index marks on the housing the way Celestron does.



#10 dswtan

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Posted 03 May 2021 - 07:13 PM

Familiar with Losmandy and Celestron CGX, this article is very helpful for my CEM25, which is still a new alien beast to me!



#11 redsan

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Posted 04 May 2021 - 12:42 AM

Sideways is not an option -> do turning the DEC 90 deg and setting it as the Zero position didn't do the trick?



#12 Michael Covington

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Posted 04 May 2021 - 11:28 AM

Sideways is not an option -> do turning the DEC 90 deg and setting it as the Zero position didn't do the trick?

No.  You will not then have full range of movement in declination.  The dec axis cannot swivel around and around -- it has cables inside.



#13 ranvis

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Posted 08 May 2021 - 12:21 PM

1st Para of "Quirks" - "If you put the GEM45 mount head on the tripod and don't add the counterweight bar, you'll find that it is top-heavy and will turn upside down when the RA gear lock is released. This is not a risk with the CEM40." is very important. 

However, newer / late versions of CEM40 (~EC, ~G) come with shorter CW Shaft (280mm instead of 410mm as in its early version). CW Shaft length shorter by 130mm may be different in getting upside down matter. I have seen one person on FB telling that his CEM26 mount saddle portion is heavier than the CW shaft portion on removal of CW cap. So owners of such mounts should cautious in this regard. 



#14 ranvis

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Posted 08 May 2021 - 12:21 PM

The above point may help avoid unexpected damage. 



#15 fielderda

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Posted 08 May 2021 - 05:50 PM

Excellent notes Michael, especially since I'm upgrading from a CGEM mount.

 

I've been waiting for my GEM45 since Dec 26th and hope it will arrive before Christmas!

 



#16 Jason27183

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Posted 08 May 2021 - 07:49 PM

Connection error detected: Dec board

 

Thanks for the article.  I just got a used GEM45, read your article and decided to try the "Search zero position" command.  It spun the RA axis around and found it's "zero" position, but then the DEC control stopped working.  I power cycled the mount and got a "Connection error detected: Dec board" error.  

 

2 hours later I had pulled about 50% of the mount apart and found that the internal wiring had gotten wrapped around the RA axis and pulled the wires out of the main control PC board.  Luckily I was able to fish the wires out from around the RA axis w/o pulling the RA axis out of the mount.  I reconnected them and got it working again.

 

I'm willing to bet that this is going to be a significant problem with this mount.

 

EDIT:  Apparently there are two hard stops for the RA axis.  A screw provides this hard stop for each one.  Apparently one of my hard stop screws is backed out, missing or bent and it didn't stop the RA axis from turning too far.


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#17 Michael Covington

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Posted 09 May 2021 - 03:28 PM

Connection error detected: Dec board

 

Thanks for the article.  I just got a used GEM45, read your article and decided to try the "Search zero position" command.  It spun the RA axis around and found it's "zero" position, but then the DEC control stopped working.  I power cycled the mount and got a "Connection error detected: Dec board" error.  

 

2 hours later I had pulled about 50% of the mount apart and found that the internal wiring had gotten wrapped around the RA axis and pulled the wires out of the main control PC board.  Luckily I was able to fish the wires out from around the RA axis w/o pulling the RA axis out of the mount.  I reconnected them and got it working again.

 

I'm willing to bet that this is going to be a significant problem with this mount.

 

EDIT:  Apparently there are two hard stops for the RA axis.  A screw provides this hard stop for each one.  Apparently one of my hard stop screws is backed out, missing or bent and it didn't stop the RA axis from turning too far.

Bingo -- very similar to a problem I had in the very early days with my mount.



#18 PABresler

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Posted 09 May 2021 - 05:30 PM

I have a CEM40; it took a while to get it going but I am happy with it now. A major glitch, that actually took weeks to figure out was that the Ipolar camera was off. The mount would not track. It turned out that the polar alignment was significantly off. PHD2 showed a large polar alignment error. I finally put a guide scope and camera on the mount and checked it with Sharpcap, and got a good polar alignment. Then I re-centered the I polar camera. It seems to be ok now.

 

I find objects using plate solves with SGP. This works fine with this mount now, although often the first solve requires a blind solve. Then the PS2 solves work. This probably is because I do not do a one star alignment. I am tired of finding stars with the laser pointer!

 

Peter



#19 dagadget

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Posted 09 May 2021 - 07:12 PM

We do need some notes.  I can only write about the mount I actually have (a GEM45 with a low serial number) and am relying on the rest of you to gather the rest of the information.

As to how to use a bubble level to find zero position, I'd have to actually play with the mount a bit before saying.  It's tricky.  I wish iOptron would print index marks on the housing the way Celestron does.

I have a GEM 45 that I purchased back in November. Never looked for a serial number but mine will also be low. I have mine in the aluminum case with the clutches off (it moves around when I take it out). Once I get it set up in my hand I lock them. Based on your article I assume that I am doing it correctly. I unlock it when I put the counter weight bar and counter weights on then lock it when I mount the huge AT 152EDT on it.  I have not done much with the Ipolar yet but I do have the software loaded onto my Laptop and I have started it and messed around with it. Soon I will be setting a table up in the driveway hooking the Laptop to the Ipolar and doing the alignment. Going to be interesting in the fact that my IEQ 30 Pro has the standard Polar scope which is very nice. IEQ 30 also has way different clutches than the GEM. Anyway with one CGEM and two Ioptron mounts it can be very interesting around here.



#20 ranvis

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Posted 12 May 2021 - 12:38 AM

Conclusion on comparison between the two mounts - GEM45 and CEM40 on the matter of getting upside down (even if its CW bar is attached and when RA is unlocked) may not be always same since all of early and late versions are not same. There are some differences in CEM40 itself. 

The CW shaft/bar length of GEM45 is 280mm. In early version of CEM40 it is 410mm and in the late versions of CEM40 the length is 280mm (shorter by 130mm). It matters when on a pivot. Probably this shortening is responsible for such unexpected dis-balance. So it is better to be cautious and and careful also in case of CEM40.



#21 Michael Covington

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Posted 12 May 2021 - 06:03 PM

My understanding is that the CEM40 cannot go upside down because of the shape of its housing.

The GEM45 can go upside down, and will do so if the RA is unlocked with no counterweight bar at all installed.  There are stops in it that should prevent this, but in fact it can slip past them.  My understanding is that the stops are screws that are often not quite far enough in.  They can be backed out to release a mount that has gone past the stop and can't get back to where it was.  They are visible if you set the mount to the highest latitude and then remove the latitude lock bolts and raise it even higher.



 


Edited by Michael Covington, 12 May 2021 - 06:05 PM.


#22 Tech Wreck

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Posted 15 May 2021 - 11:07 AM

Where is the Serial Number located on a GEM45? I can't find one on my GEM45EC.



#23 bud3161

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Posted 15 May 2021 - 11:38 PM

Very good article. I got a GEM 45 back in October 2020 and it's a real pleasure to use for the most part. So far any cussing I was doing at the mount was usually because I did something wrong. To date, I have not had the problem described above with the power cable size. 

I bought 2 different brands of 5.5mm x 2.1mm x 6ft cables and they both worked. I ordered a random brand power supply with 5.5x2.1 connector and it fit fine and it is now powered by the 2ft cord provided with the Pegasus power box advanced and that one fits fine. Now the 2 USB cables in the shaft nut are pretty loose in their sockets with every cable I have tried and they are shallow in depth compared to the length of the USB 2 cables I have used. The greatest advantage I think this mount has is the internal routing capability for my cables. I run a USB 3 cable and 3 5.5x2.1 power cables through it with no problem. The cables all connect to the PPBA. The power cables are used as follows, one is 12 volt to 12 volt automotive bayonet plug, one is a 12 volt male to male so I can connect it to the 110 power supply and a 2 foot one from the PPB to provide power to the mount. I am thinking about getting another one of these GEM 45's or possible a GEM 70 for an 8" SCT for mostly visual astronomy and to have the mount to move to a larger setup later.


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#24 Magnetar_29

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Posted 22 May 2021 - 08:53 AM

Hey... you mentioned that the gears must be off when balancing. This means that when changing counter weight right? Because while balancing we check if dec is balanced by locking the ra and check if ra is balanced while locking the dec. isnt this the way to do?


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#25 lmichel

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Posted 23 May 2021 - 07:16 AM

Wow!  Michael, terrific notes here!  I was also interested in reading content from contributors with other iOptron mounts.  I have a CEM120EC2 and even though it is an iOptron, it has its own set of quirks!  There are separate "Locks" or levers to absolutely prevent the RA or Dec from moving.  Think of them as engaging the emergency break on a car.  It's a *separate* lever - one for the Dec, one for the RA.  Then, there are the traditional levers to engage the worm.  There are warnings all over the owners manual to NEVER engage the LOCK and also engage the Clutch and try to move the mount under power.  It would be like trying to drive a car with the emergency break locked, but likely much worse since it's a mechanical lock and not friction.

On the current hardware release of the mount, there is no 'sensor' or device to prevent/warn you that both levers for either axis are in the locked/engaged position!   

 

Mounts are approaching the complexity of aircraft flight decks!  :)




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