Is this tilt in the image train?


Dean Jacobsen
 

On Mon, Sep 27, 2021 at 02:49 PM, Joseph Beyer wrote:
Initially I connected my filter wheel to the camera with the stock tilt adjuster sandwiched in between.  Images were terrible with elongation of stars nearly across the frame.  I removed the tilt adjuster and immediately got better stars but not great yet.
Interesting.
--
Dean Jacobsen
Astrobin Image Gallery - https://www.astrobin.com/users/deanjacobsen/


Tom Blahovici
 

Yes I have noticed this myself. Stacking the images usually reduces the abberations.
The direction of tilt shown by CCD inspector is the same as before. I wonder if the new ap mount is now more accurate now that the stars are more steady. 
Before I would have 0.7,-0.8 arc sec RMS tracking, now down to .25.
Tom


Tom Blahovici
 

Well my first shot at this was pretty poor. I had very inconsistent results, that overshot what they should be been when I adjusted the tilt plate. They they went in the wrong direction! I finally got fed up and put everything back to flush with the scope.
I got to thinking though. It really was a very very slight adjustment to the tilt screws that was needed. I was also locking down the push pull screws quite a bit. 
So I though perhaps the tightening is distorting the actual situation. So I tightened up just the pull screws which put the tilt plates flush with the telescop and just slightly tightened the opposing screws.
Result? My stars are perfect across the whole field.
So what I though was tilt or miscollimation, turned out to be a distorted field due to overtightrning the adjustment screws.
I'm back in business!


Roland Christen
 

Great!

Rolando



-----Original Message-----
From: Tom Blahovici <tom.va2fsq@...>
To: main@ap-gto.groups.io
Sent: Tue, Oct 5, 2021 7:40 pm
Subject: Re: [ap-gto] Is this tilt in the image train?

Well my first shot at this was pretty poor. I had very inconsistent results, that overshot what they should be been when I adjusted the tilt plate. They they went in the wrong direction! I finally got fed up and put everything back to flush with the scope.
I got to thinking though. It really was a very very slight adjustment to the tilt screws that was needed. I was also locking down the push pull screws quite a bit. 
So I though perhaps the tightening is distorting the actual situation. So I tightened up just the pull screws which put the tilt plates flush with the telescop and just slightly tightened the opposing screws.
Result? My stars are perfect across the whole field.
So what I though was tilt or miscollimation, turned out to be a distorted field due to overtightrning the adjustment screws.
I'm back in business!

--
Roland Christen
Astro-Physics


Andy Ermolli
 

Glad you got it sorted. 
Bill is right, my FSQ went back to Japan. It took 11 months since I sent it to Huston to the time I got it back, it was worth it. I suspect that there are many FSQ's out there that need to be collimated. In my case I believe the Pezval elements (G3 and G4?) needed to be adjusted and that can not be done in Houston.


Joseph Beyer
 

Looks great!  Glad to see you've got it fixed and are ready to go.  I got the CTU on my telescope and adjusted fairly well.  Just like you I was surprised how little movement the camera needed to flatten the field.  Now all I'm waiting on are clear skies.  


Tom Blahovici
 

11 months. That's nuts!