Zwo EAF and moonlight

Hi Dan  I am also in Portland. I travel to do all of my imaging.  I would certainly try to image here in town with narrow band filters if I had more sky available in my yard.  However for your situation I would try adding some time to the auto focus. Maybe you have a default of 2 sec? 4sec?   You might try 10 sec?   I had similar problem and lengthening the exposure time helped.

For me the solution to exact same problem was to first measure the focuser backlash and then set up the measured value in autofocuser configuration. Did you do it? Its an important step.

There are a few things that can go wrong with autofocusing:

1) as others have said the exposure time for narrowband autofocusing needs to be quite long.
2) Finding a sensible step value is essential. Too small and you don't properly sample the curve so the fitting results are nonsensical. Too big and you run the risk of going so far off focus that the fitting points don't lie on the expected curve. I've found that no matter what metric is used (FWHM, HFD, inv-power etc) if you move too far from focus the curve stops being hyperbolic (or whatever ideal shape it should be) and the fit result will be poor.
3) Make sure the stepper has enough range either side of focus to properly sample the curve. I think you can set the '0' point arbitrarily on the ZWO EAF and it should probably correspond to when your focuser is fully racked in. This is a problem with some camera lenses with an infinity stop - but it shouldn't affect your setup.

Probably the best way is just to dedicate half an hour at the beginning of a session to get all the offsets and stepper sizes sorted out. Manually focus with a bat mask and then play with the stepper values until the EAF can consisently land you on focus, then you should be all good to go. For a first attempt I'd do this with luminance so you can use short exposures. Once you've got it working with L, then you can up the exposure time and see if it is also consistent with the NB filters. Once you have everything correctly calibrated you shouldn't need to touch the values again.

Yeah, I completely agree. EAF is great. I already own two of them. Let us know when you sort it out. I would be interested to know what caused the problem.

As others mentioned, you probably need to do the initial calibration if you haven't already.  Here's a video from Cuiv, The Lazy Geek (great channel) about how to do it in NINA. https://youtu.be/-sHzbz3OcSo?si=XL0Y9nZayRHO08Mc

If you're using ASIAir the same principles apply, you just need to find the right settings in that software

To add to what others have stated, see if your image capture software allows to increase the gain during focusing.
I have four EAF's, and for narrowband I use 5 to 10 seconds of exposure, at a higher gain than during regular capture.
But make sure the software switches the gain back.
And to repeat:  Correct starting point, correct step size between attempts (approximately 2X to 3X FWHM or HFD for entire range of focus attempts), and whatever backlash corrections are available (I use an "inward move" of around 200 steps in APT.  NINA has an equivalent called "backlash compensation overshoot" under option>equipment>focuser>advanced settings"    I'm not sure about ASIair)
Good luck!
Steve

Hi Dan, I had also Problems with the EAF, please try in N.I.N.A to chang:
at first the the Autofocus step size (is it to big or to small then it didn't work).

Autofocus step size 50-100.

Next try
Backlash start with 40/40 make a test.

I use a 8"Newton
exposure time = 5 - 6 sec. ist ok.

Then Autofocus initial offset steps = 4

Take care: If you start the autofocus prozess -> the scope has to be nearly in focus!

good luck, br and cs
Hampo