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Eyepiece too heavy for my focuser?

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#1 kklei940

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Posted 16 July 2020 - 09:05 AM

Last night I wanted to check out my new Celestron Ultima LX 22mm in my 6" Omni XLT-150 newt. I popped it in the 2" crayford focuser and it wouldn't come to focus. No problem there, I went inside and grabbed a 2" extension tube. I was now able to reach focus but when I took my fingers off the focuser dial the drawtube slowly crept back down and I would lose focus. I tried adjusting the tension on the focuser with the set screw to see if that would help, but that didn't really work. I then just thought I would completely lock it down with the set screw when I got to focus, but as soon as I tried that and let go it would fall out of focus slightly.

 

I'm wondering if there is some sort of adjustment that can be made to the stock crayford focuser to help it handle the weight of the eyepiece and extension tube or if it's time to invest in a new focuser to handle these heavier eyepieces? I plan on purchasing a coma corrector eventually and know this will add more weight as well. Any insight would be much appreciated. I've attached a picture of what my focuser looks like below. Thanks in advance!

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#2 gene 4181

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Posted 16 July 2020 - 09:35 AM

  There is a tension allen screw that pushes up against the focuser axle  shaft underneath .   Your focuser  is a crayford (?)  on the 150 Omni ? ,  It is a metric allen


Edited by gene 4181, 16 July 2020 - 09:37 AM.


#3 Shorty Barlow

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Posted 16 July 2020 - 09:36 AM

I've had a similar problem to this but with 2" diagonals and heavy eyepieces. Eventually the only solution is to replace the focuser.



#4 kklei940

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Posted 16 July 2020 - 10:09 AM

  There is a tension allen screw that pushes up against the focuser axle  shaft underneath .   Your focuser  is a crayford (?)  on the 150 Omni ? ,  It is a metric allen

I just checked it out and it looks like you're right, there is an allen screw underneath there. I'll play with this a bit and see if it does the trick. If not then I guess I'll have to consider a focuser upgrade. Thanks for the help!



#5 Starman1

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Posted 16 July 2020 - 02:06 PM

It's just an adjustment.  The focuser in question can be adjusted to handle 4 lbs easily.


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#6 kklei940

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Posted 16 July 2020 - 02:29 PM

I tried the adjustment and it worked great. What a simple fix that was. Thanks again everyone!


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#7 Junoscope

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Posted 28 July 2020 - 06:11 PM

For focusers that don’t have a tension screw, you may be able to remove one of the focuser knobs and stick a circle of the loop portion of a Velcro strip on the side of the knob that goes toward body of the focuser.  You’ll need to punch a hole in the center of the Velcro for the focuser shaft.  Snug the knob against the focuser and tighten it.  

 

I found that this method works well with an older Feather Touch focuser which doesn’t have a tensioning screw. The focuser now supports a Paracorr 2 and 100 degree eyepieces without slippage. 




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