Meade SCT & EAF

Peterpsbradford

Hi all - Inspired by the "plan" function, I decided to attempt to make the camera system work with my Meade SCT. With a simple block of wood, I created a platform to attach the EAF to the focuser. So far, my only connection is to the fine focuser knob which doesn't seem to generate sufficient variation in focus (above seeing variations) to help the ASI PRO focuser routine to converge on the ideal focus point. I've changed step-size to the maximum 200... but am out of ideas. Anyone else attempt this before? Are there other software configuration options that might increase the variation between focus steps or scale the movement per step?

Larger image here: https://www.icloud.com/sharedalbum/#B0q59UlCqGHzkpA

Thanks,
Peter

Tech@ZWO

Peterpsbradford
Don't recommend connecting to the fine focuser knob, it may take a long time to focus.
Connect to the coarse focuser knob and set the AF steps to 30-60 to try.

Peterpsbradford

I would gladly settle for "a long time". In my experience with seeing variations, the curve is so flat and variable that the EAF + ASIPRO doesn't converge on the optimum focus point. I think I would need a step-size well above 200 for it to work, but that is limited by the software interface. I will see if I can mate it with the coarse focuser knob, since that is the ideal situation for the EAF.

w7ay

Peterpsbradford In my experience with seeing variations, the curve is so flat and variable that the EAF + ASIPRO doesn't converge on the optimum focus point.

Depends on whether you are willing to keep investing in the SCT, you can also add a Crayford focuser. You can lock the main mirror, and focus with the EAF attached to the Crayford. That will work around the short comings of the ZWO EAF (the real solution is for ZWO to fix the EAF firmware to make it usable).

Chen

Tech@ZWO

Peterpsbradford Could you tell us why you prefer to connect it to fine focuser knob?
You can try the coarse focuser knob first to see if it works fine.

Peterpsbradford

Tech@ZWO I preferred the fine focuser knob to have a more accurate final focus. After months of working on this, I realize the program step-size is limited to ranges that make the fine-focuser solution ineffective for achieving ideal focus. I found a way to connect it to the coarse focus and generally achieve good results by changing the step-size from around 60 with my Tak-130 to 120-150 range. I believe the fine focusing step sizes still provide the necessary accuracy for final focus.

DavesView

Check out Agena Astro: GSO 2" EAF Compatible Linear Bearing Crayford Focuser for SCTs - Dual Speed

Peterpsbradford

Just to close this thread, I ultimately found a way to connect the assembly to the coarse focuser knob and the mechanical adjustments of the EAF are sufficiently small (with results confirmed with Bahtinov Masks) that I don't question the accuracy I'm able to achieve.