No, I would not be satisfied with v-curves that look like that.
As an example, I'm attaching images of several v-curves from my session the other night.
Admittedly, I'm using a 105mm refractor (with a Moonlight V2 controller), which I'll bet is much easier to focus that a RASA, but you should aim for V-curves.
I'd recommend
- use the Linear Focus algorithm
- use the SEP detection
- use Full Field with a 20% 80% annulus
- 5% tolerance
- no dark frame
- I expose for 3-5 seconds using my f/5.6 scope.
- You'll need to figure out your "initial step size".
If the initial step size is too small, then you might get noise, like your plot shows.
Take some time to get things right the first time. So, under decent skies, first manually focus, until you have an image
that's sharp to your eyes, or better yet, get sharp focus manually using a Bahtinov mask.
Once in focus, tune your initial step size by running autofocus as I described above. Play with the step size.
Here's how you might get an inital step-size value: move slightly off focus and find a step size that moves the focus from an HFR of 1.5 to 1.25 or something like that.
Not too important to be exactly that, but you want to see some change in the focus HFR.
[The focus tab has a "start framing" button, two arrows pointed opposite ways, that can help with doing this].
Now that you have an initial guess for the step size, run autofocus. Hopefully you'll see a decent v-curve.
If you want, change the initial step size a little and iterate. Best to get a decent curve, even it you wind up with 15-20 samples,
than something quick that doesn't look reliable.
I'd avoid playing with max travel (keep it very large), backlash (keep it 0), out-step multiple (keep it at its default of 5).
Let us know how it goes!
Hy