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How to Remove Periodic Error in an iOptron Cube Mount?

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#1 tmiddendorf

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Posted 21 March 2019 - 05:42 AM

I purchased a used iOptron Cube mount a few months back to mount a DSLR to photograph the lunar eclipse. It went ok. But in putting the images together to make a movie of the eclipse it was obvious the PE was in the order of 100+arcsec. Has anyone experienced this in a Cube? Anyone have solutions to remedy the PE in these mounts?



#2 Skymind

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Posted 21 March 2019 - 06:58 AM

How did you determine the PE in an Alt-Azi mount? When tracking with an Alt-Azi mount, both axes rotates in different speeds, and the speed varies from point to point, so PE is pretty much meaningless. 



#3 tmiddendorf

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Posted 21 March 2019 - 07:52 AM

How did you determine the PE in an Alt-Azi mount? When tracking with an Alt-Azi mount, both axes rotates in different speeds, and the speed varies from point to point, so PE is pretty much meaningless. 

I put the Cube into equatorial mode using iOptron's equatorial wedge tripod. I configured the hand controller for equatorial mode. My setup was using a 100mm lens on my Canon DSLR on the Cube. I exposed at under 30 sec. I combined these into a video and the Periodic Error showed itself as the moon in the video rising and falling in the frame.



#4 rmollise

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Posted 21 March 2019 - 09:35 AM

I doubt you will ever get the PE down to really low levels with this mount. However, you can likely improve it. I would guess being scrupulous about balance will help.


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#5 tmiddendorf

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Posted 21 March 2019 - 09:53 AM

Agreed I will never get it very low. I'm just hoping to get is closer to 10's of arcsecs. Thought maybe others on CN may have dove into theirs.

 

I doubt you will ever get the PE down to really low levels with this mount. However, you can likely improve it. I would guess being scrupulous about balance will help.



#6 Skymind

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Posted 22 March 2019 - 08:30 AM

I put the Cube into equatorial mode using iOptron's equatorial wedge tripod. I configured the hand controller for equatorial mode. My setup was using a 100mm lens on my Canon DSLR on the Cube. I exposed at under 30 sec. I combined these into a video and the Periodic Error showed itself as the moon in the video rising and falling in the frame.

Well, that's another story. EQ mount is the worst to track the moon, which requires both axes tracking and DEC at variable speed. So far very limited mounts in the market are capable doing such thing and are all very expensive. So, using the moon to estimate the mount PE is not the best choice. One the other hand, I would not expect too much on an entry level mount under $300 to perform the same as a full function EQ mount.


Edited by Skymind, 22 March 2019 - 08:37 AM.



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