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CEM25P Not stopping at Zenith

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#1 vishadow

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Posted 27 May 2020 - 11:13 PM

Hi All,

 

This is probably a very novice question for Goto/tracking mounts, but I need help in understanding how to stop the mount from slewing past what appears to be 90 degrees. The mount has routinely slewed to the point that the DEC unit makes contact with the side and makes light grinding sounds (I assume that gears are slipping) before I stop it with the hand controller. After that, zero position is way out of whack.

 

This doesn't appear to cause any significant issues as it continues to work fine after resetting zero position. I've mainly noticed this inside, as there has only been one clear night since I received it two weeks ago.

 

Is this more of an issue because I don't have GPS lock and proper polar alignment when using it indoors? I am using Stellarium to slew and attempting to plan a sequence of imaging based on what's visible at various times. 

 

I noticed the "Meridian Treatment" settings on the hand controller, but left them at the default values.

 

Any tips or clarification would be great.

 

Thanks,
Mike



#2 OldManSky

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Posted 27 May 2020 - 11:35 PM

Do use the "Meridian Treatment" options.  You can either have it stop tracking or do a meridian flip -- which one you choose depends on what you're doing (if you're observing visually, it might be jarring to have it just take off and do a flip while your eye is at the eyepiece!).  You can also set how far past the meridian the action will occur -- I used 5 degrees past with my CEM25.


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#3 vishadow

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Posted 28 May 2020 - 12:27 AM

Do use the "Meridian Treatment" options. You can either have it stop tracking or do a meridian flip -- which one you choose depends on what you're doing (if you're observing visually, it might be jarring to have it just take off and do a flip while your eye is at the eyepiece!). You can also set how far past the meridian the action will occur -- I used 5 degrees past with my CEM25.


Thanks for the recommendation!

Edited by vishadow, 28 May 2020 - 12:28 AM.

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#4 PaulE54

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Posted 28 May 2020 - 01:49 AM

Another point to watch is that the CEM25, like my CEM40, will memorise it's position when the power is lost or switched off (manual page 24). This means that you should always park to zero position at the end of a nights observing, and start from zero at the start of the next nights observing. If you instead switch off with the mount NOT at zero, then manually release locks and move the mount to zero when you shut down, the next time you turn the mount on, it won't be where it remembers it was....

All kinds of bad and confusing things can then occur, including slews that are nowhere near the object you were aiming for and tracking way past the meridian.

Not that this has every happened to me.....:-)

 

Clear skies.

 

Paul  


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#5 vishadow

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Posted 28 May 2020 - 01:10 PM

Another point to watch is that the CEM25, like my CEM40, will memorise it's position when the power is lost or switched off (manual page 24). This means that you should always park to zero position at the end of a nights observing, and start from zero at the start of the next nights observing. If you instead switch off with the mount NOT at zero, then manually release locks and move the mount to zero when you shut down, the next time you turn the mount on, it won't be where it remembers it was....

All kinds of bad and confusing things can then occur, including slews that are nowhere near the object you were aiming for and tracking way past the meridian.

Not that this has every happened to me.....:-)

 

Clear skies.

 

Paul  

Thanks Paul! I've only used the mount once for imaging, so any tips to add to my routine is great. 




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