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Tip/tilt adjuster for SCT 3.29" thread visual back?

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#1 Whichwayisnorth

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Posted 02 June 2020 - 04:08 PM

I know they exist for cameras but is there one that threads onto the factory 3.25/3.29 inch visual back threads of an SCT and provides the same size threads for accessories?

 

Would be nice to correct tilt that exists in the OTA which mine seems to have.

 

For example,  I am looking at this video from Hotech https://youtu.be/4BDwa0RVZw0?t=294 and in this section it mentions that the returning cross hairs are off because of tilt.  Then the example shows that the guy adjusts the Moonlite focuser to compensate.

 

I do not use an external focuser so I can not replicate that step.

 

However if I had some kind of tip/tilt adjustment that then allows me to thread on the 2" visual back that my Diagonal and eyepiece, DSLR, or ASI Cmos camera can slide into, that would work out great.

 

Something like this https://agenaastro.c...ation-ring.html


Edited by Whichwayisnorth, 02 June 2020 - 04:08 PM.


#2 junomike

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Posted 02 June 2020 - 06:18 PM

The 3.29" threaded VB is part of the actual housing also houses the Baffle tube so if the Housing/3.29" threads are off, the Baffle tube will be as well.

My guess is in the video he's compensating for the Focuser being out of alignment.



#3 Whichwayisnorth

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Posted 02 June 2020 - 07:26 PM

The 3.29" threaded VB is part of the actual housing also houses the Baffle tube so if the Housing/3.29" threads are off, the Baffle tube will be as well.

My guess is in the video he's compensating for the Focuser being out of alignment.

I agree.  I think I have that issue.  Actually what I think is that the entire rear SCT housing that the telescope tube slides into and bolts together may be off alignment and was glued in place.  I know that it is possible to remove the bolts and somehow get the two pieces to come apart but I feel I will risk damaging things if I put too much effort into it.  It isn't horribly off center but enough to show up with the return laser cross hairs on the panel.   I'd love to be able to adjust it at the rear of the scope so that anything I thread on will start with an accurate foundation.



#4 junomike

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Posted 02 June 2020 - 09:06 PM

Not sure on this so hopefully someone in the know will chime in but.......

 

The Primary and Secondary are aligned as one and if the Primary is tilted (as in your case) then the Secondary has to be tilted in the same to reach collimation.

This is usually not an issue and more people use the SCT like this.

 

Now, If you were to tilt the VB to against the mirrors, then along with cutting down the Aperture (due to light loss in the Baffle) you may run into other collimation issues.



#5 Ettu

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Posted 03 June 2020 - 11:16 AM

Gerd Neumann makes a solid tilt/tip adjustor, but the size you're looking for is pricy

 

 https://optcorp.com/...ab5a94d72f687fe

 

Plus the adaptors you'd have to get. They do make an M48x0.75 (standard 2" threads) version for $200



#6 Whichwayisnorth

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Posted 03 June 2020 - 11:58 AM

Gerd Neumann makes a solid tilt/tip adjustor, but the size you're looking for is pricy

 

 https://optcorp.com/...ab5a94d72f687fe

 

Plus the adaptors you'd have to get. They do make an M48x0.75 (standard 2" threads) version for $200

A machine shop should be able to make one for quite a bit less.  When the world is off lock down and the Storm Troopers let us go back to our lives I will try my local shop and see if they can make me one.




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