4 replies to this topic

[Jrclodf]

Hi,

 

I have been having trouble getting guiding to work properly, and I can’t find a reason to why. I use a skywatcher EQ6R-pro, Celestron EdgeHD 8” at native focal length (waiting for reducer to come), celestron OAG with the 174mm mini for guiding, and a 294mc pro main camera. I also used an Optolong l-extreme 2” filter for the pictures that I attached.

 

Guiding usually starts out at around .5”, but throughout the night it ends up at around 1”. In the picture, guiding was at .7”, and I attached the picture taken that night which is zoomed in on the stars. The stars are elongated. Also, the guide star looks very misshapen because that was the best focus I could get on the OAG.

 

Everything is balanced and my polar alignment error was .15”.

 

If anyone has any ideas or solutions, please let me know.

Thanks

Attached Thumbnails

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Edited by Jrclodf, 07 September 2024 - 12:31 PM.

[kathyastro]

Any time you have elongated stars, the most important piece of data is what direction is the elongation?  It looks vertical in your photo, but that depends on camera orientation.

 

Looking at your guiding graph, Dec is much better than RA, so I would guess that the elongation is in RA.  I haven't used the ASIAir, so I don't know what guiding modes it has, or whether it can compensate for periodic error.  Make sure that whatever periodic error compensation you have available, either in the mount or in the AA, are turned on.  Also check the mount's RA backlash, and the balance of your rig.  If backlash is a problem, people often compensate by balancing the rig very slightly east-heavy.

[Sky King]

 

I have this setup and trying to do anything at focal length 2089 is tough. Since I got my .7 Celestron reducer I don't take it off. This image was at FL 2089. Now I'm at 1479 with the reducer.

 

If your EQ6-R guides well with other scopes, blame that focal length.  Maybe try shorter exposures.

 

 

Edited by Sky King, 07 September 2024 - 02:57 PM.

[Jrclodf]

Any time you have elongated stars, the most important piece of data is what direction is the elongation?  It looks vertical in your photo, but that depends on camera orientation.

 

Looking at your guiding graph, Dec is much better than RA, so I would guess that the elongation is in RA.  I haven't used the ASIAir, so I don't know what guiding modes it has, or whether it can compensate for periodic error.  Make sure that whatever periodic error compensation you have available, either in the mount or in the AA, are turned on.  Also check the mount's RA backlash, and the balance of your rig.  If backlash is a problem, people often compensate by balancing the rig very slightly east-heavy.

It is always vertical because I keep the camera orientation the same. I never changed any settings on the Asiair guiding, so I’m guessing that periodic error compensation is on. I don’t see any backlash problem in both RA and DEC, and the mount is balanced. I haven’t tried out balancing it east-heavy so I might try that.

[michael8554]

1.  The focused star shape in OAG is often elongated but PHD2 copes.

 

2.  RA guide error is twice that of Dec:

Dec = 0.31,  RA =  0.69.

So as kathy said, you would expect elongation in RA.

But you still haven't verified that ?

 

3. However, if your imaging camera's pixel scale is larger than 0.69arcsec/pixel, then the guide errors are less than 1 pixel, meaning round stars.

 

4. You may need more guide Aggression and smaller Minimum Move in RA to correct the  excursions.

But I don't know if the "lite" version of PHD2 in ASIAir has those settings ?