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Guiding with ASIAir Pro and Gemini-II Level 6

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Hello everyone,

I'm transitioning from primarily visual observing with the Gemini-II system to astrophotography and would appreciate some advice. My current imaging setup is as follows:

  • Takahashi TOA-130NFB with the 645 Field Flattener
  • ZWO ASI 6200MM
  • ZWO OAG-L with ASI 174MM Mini as the guide camera
  • Losmandy G11G with Level 6 upgrade
  • ASIAir Pro for running imaging sessions

While the imaging hardware itself is solid, I'm struggling to dial in the guiding settings on the ASIAir Pro to achieve good results. I'm dealing with elongated stars and inconsistent guiding graphs. I'd love some suggestions for baseline settings to get started, especially considering the focal length and mount.

Parameters I¡¯m looking to optimize:

  • Gain (for the ASI 174MM Mini guide camera)
  • Calibration Step Size
  • Max DEC Duration
  • Max RA Duration
  • Dither settings
  • Guide Camera Binning (1x1 or 2x2)
  • Dark Library (Yes or No)
  • Guide Exposure Length
  • RA Aggressiveness %
  • DEC Aggressiveness %

Notes about the setup:

  • My focal length is ~1000mm with the TOA-130 and field flattener.
  • The Losmandy G11G is well-tuned with the Level 6 upgrade, but I'm still learning how to best use it for imaging.
  • I typically image under moderately dark skies.

If anyone has experience with a similar setup, I¡¯d appreciate any tips or recommended settings to get better guiding performance. Any tricks or advice specific to the ASIAir Pro with an OAG setup would also be super helpful!

Clear skies,

Ryan
 
Edited

I have the ZWO 174 MM mini in their OAG-L with AA+ and it works well. ?
¡°Unity¡± gain is 68 and if you choose medium gain in the AA+, I think that is where it sets it. I just leave it at 68 for 90% of the time. ?
Yes to dark library, cuts down on hot pixels which can improve guiding
I am still waiting to build my observatory so I really have minimal experience with the AA plus and the G11G, so no help there (using AM5 for now).
I dither 5 pixels every frame when shooting 300 second subs, and every 3rd frame for 120 second & below subs (just so I don¡¯t loose too much of my very limited imaging time).
Calibration step size is a convoluted, multi step formula based on guide camera image scale, guide scope exposure length ?divided by time (drift of the sky across your guide camera sensor). ?The AA+ must get 25 (pixels or arcseconds, I forgot which) within 65 steps or it fails and there is a strong opinion to reach that 25 in about 15 steps for best guiding. So start around 500 and go up or down from there. It is linear so a 1 second guide exposure will have twice the calibration step of a 1/2 second calibration step.
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Calibration step formula

Target move = guide camera arcsec per pixel x 2 pixels per pulse

Calibration pulse in ms = target move / time.

Calibration pulse = target move / (15 x guide rate in seconds)

(Time is 7.5? for 1/2 second, 15 for 1 second, 30 for 2 second guide rate)

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I keep my aggression as low as possible. ?It varies based on seeing. ?Start below 50 and work down until guiding starts to get worse.

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Report back what you found works for your setup on average seeing nights.

Good luck.

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