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Image shift with a Moonlite focuser? Help!

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#1 HH_ASTRO

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Posted 13 June 2018 - 12:40 PM

After fixing my previous problem with my new Moonlite focuser, I now have a different problem. When I focus in, the stars move down.

Does anyone know what the problem is???

#2 havasman

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Posted 13 June 2018 - 01:26 PM

Most unusual. You should definitely contact Moonlight.



#3 Eddgie

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Posted 15 June 2018 - 09:18 AM

Don't know what you did but assuming the bearings are not bad, I'd you played with the pinion support backing bearing, it is probably not tight enough to hold the pinion shaft against the tube flat and when you change focused position, the tube can deflect away from the bearings.

 

If your load is very heavy, the tube can say away from the bearings.

 

If it is the first, then tightening up the nylon bearing backing plate by using the small screws on the pinion backing plate.  If you can get it right enough to stop the deflection and still have smooth movement you are good to go.

 

If you are using a heave load like gunpowder though, you may have to use so much tension that the focuser motion becomes stiff.

 

I felt that the Moonlight struggled with binoviewers and wound up selling it and replaced it with Feathertouch, which was vastly better for this kind of load with zero deflection.

 

And just an aside.  I was always re-collimating with the Moonlight. I did not at first realize that it was the focused tube sag causing this.  After going to FT, the need to collimate went away.  The bolts time I need to re-collimate my 12' truss is when I change mirrors.

 

If your load is normal though, suspect improper tension on the nylon pinion bearing backing plate.



#4 HH_ASTRO

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Posted 15 June 2018 - 05:13 PM

Don't know what you did but assuming the bearings are not bad, I'd you played with the pinion support backing bearing, it is probably not tight enough to hold the pinion shaft against the tube flat and when you change focused position, the tube can deflect away from the bearings.

 

If your load is very heavy, the tube can say away from the bearings.

 

If it is the first, then tightening up the nylon bearing backing plate by using the small screws on the pinion backing plate.  If you can get it right enough to stop the deflection and still have smooth movement you are good to go.

 

If you are using a heave load like gunpowder though, you may have to use so much tension that the focuser motion becomes stiff.

 

I felt that the Moonlight struggled with binoviewers and wound up selling it and replaced it with Feathertouch, which was vastly better for this kind of load with zero deflection.

 

And just an aside.  I was always re-collimating with the Moonlight. I did not at first realize that it was the focused tube sag causing this.  After going to FT, the need to collimate went away.  The bolts time I need to re-collimate my 12' truss is when I change mirrors.

 

If your load is normal though, suspect improper tension on the nylon pinion bearing backing plate.

Where is the pinion support backing plate?? I am having changing collimation issues... could it be the Moonlite?



#5 Hondo

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Posted 15 June 2018 - 06:43 PM

Contact Ron at MoonLite.  His customer service is second to none.


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#6 Eddgie

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Posted 15 June 2018 - 10:55 PM

Where is the pinion support backing plate?? I am having changing collimation issues... could it be the Moonlite?

If you look at this picture you will see two hex head screws recessed into holes on the flat surface between the focused knobs. These push against a metal plate that holds the Teflon pad against the focused drive shaft. If the bearing is not tight against the shaft then the weight of the eyepiece can deflect the focused.

 

If you bought this new then this should have been set correctly.  If you moved either of the screws you may have to check them.



#7 Bill Dean

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Posted 16 June 2018 - 02:34 PM

Moonlite has a video on YouTube that will shed some light and covers the adjustments.

https://youtu.be/3nCRJ37HBkI

Clear skies,
Bill

#8 noisejammer

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Posted 16 June 2018 - 06:40 PM

If you decide to tweak these screws, be very gentle! It's easy to trash the bearings.




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