I may not have much time later today to look into it, but a quick initial look shows that:
Now I'm not sure if it's sortware or hardware.
it is asking the focuser to move to a certain position to start, and the focuser doesn't get there, and the Linear algorithm doesn't
reset to the new position that the focuser is insisting on.
For instance, in the first attempt.
Starts at 10760
Linear wants to start its sweep at 11160, but does this by planning to go out to 11660, then back in 500 to 11160 (It doesn't violate max position, but it is ignoring max travel)
So it requests that the moonlight go to 11660. Indi copies that. But the focuser reports getting to 10916.
*** Do you have some kind of backlash removal active or something like that that could be confusing it?
The Linear focus seems to ignore this discrepancy and then moves back in by 500 which gets it to 10416 (instead of 11660) and now things are messed up and Linear isn't recovering well.
2nd focus session:
Starts at 11000
Plans to go out to 11900 and back to 11400.
But only gets to 11134 and then goes back to 10634.
Same finish as above.
I'm not sure why your focuser is not going out to the position requested in the first outward movement.
It seems to work fine for the inward movements, but not the outward movements.
Does it all work well in polynomial?
Can you manually command it to move out to these positions and back in?
Sorry, looked at your log and something is clearly broken (I mean likely software) for your setup.
I'll look further. Which moonlight focuser are you using?
It didn't look to me like you had any successful focus runs with Linear. Is that correct?
Yes, that's it, not absolutely necessary to avoid the center/typical target area, but if you can get plenty of stars elsewhere then why not. If you're starved for stars then see if it works fine including it. I guess removing the edges would be avoiding areas that can have more coma, which might adding noise to the hfr values.
I just images m95/m96 where the galaxies weren't centered but I didn't change the annulus, and had no issues, so it's just something to make things run more automatically, that I've adopted from others, and I've seen bad star detections, eg in the center of m31, but the averaging and outlier removal would likely have avoided issues.
I see--I do not have experience with longer focal lengths. You may be right about that. Can you up your gain as well (of course, don't clip too many stars, though).
Here's a recent sub of mine (240s blue filter 1x1 binning gain 75 bortle 5 skies) uploaded to astrometry.net for the Sunflower Galaxy: nova.astrometry.net/user_images/3492359#original (hasn't finished yet, as I write this).
This is the full resolution from the ASI1600mm pro and my refractor, and the pixel scale should be about 1.34 arcsec/pixel
I understand your argument against 2x2, I thought the same, but honestly a friend recommended it and I found he was right, it worked for me. Try it!
I think it's important to get a reasonable exposure for focus, hence the gain 200 and binning 2x2 (of course, I could use longer exposures, but that increases the time for AF, and this tradeoff seemed to work for my setup).
I focus in Ha and it works fine for me. I really think the key is getting a lot of stars to average the HFR over. Even if you can't get 70 like I do for the wide field, if you can get 20, you may find an improvement.
I was tempted originally to try and write a better star-detector/hfr-calculator, but then I realized Jasem had put in a scheme (SEP) that had been worked on for years by the pros, so I figured that was something I wasn't going to improve upon.
I get many more stars with my f/5.6 scope on a typical image.
For an R,G, or B filter I use 3s exposure, gain 200 in the focuser (ASI1600 camera) and on most of my attempts was getting ~70 stars.
For Ha/SII/OIII I use 5s and get a similar number of stars.
Also, fwiw, I use a binning of 2x2 on my focus images.
If you aren't getting lots of stars, can you try adjusting your focus exposure and see if that improves things?
I agree with the above comments, which is why I strongly recommend you use the "Full Field" focus setting (in focus tab, under settings sub-tab).
Use it with an Annulus of like 25% 80%. Doing this and it will detect many stars, throw away outliers, and then average the results. This is much more stable.
I recommend the SEP star detection algorithm also.
Finally, if you're not happy with the Polynomial algorithm, please try the "Linear" algorithm too
Jasem, Rob: Just found this thread on a web-search. A friend asked if Ekos supports tracking/shooting ISS images. It seems it does. How would you go about doing that?
Thanks for the feedback. Can you please do the following:
- Manual focus youself until you're in focus.
- Run the Linear focus algorithm with
- Full Field and the same anulus as you've used
- Detection: SEP (that should be better than what you were using with star detection & HFR)
- Experiment with gain, exposure & binning and see if you can get 50+ stars detected in each image (not absolutely necessary, but let's start there).
- Step size: same as you were using above.
- Make sure max travel is not limiting you--make sure it's very large for now
- I assume backlash compensation is off. Let me know if otherwise. (turn it off if you're having issues).
- Repeat several times or do whatever you have to do (and describe it) so that you get a failure .
- Send me a log
The linear algorithm might work when you're way out-of-focus, but it's best to start it roughly in focus.
In your example above, even though it went back about 7 steps to start, it is still too far in to start.
I can't tell if you should increase the step size, or start with better focus. Try both if you have issues.
If you can, please retry and send me a log with at least the settings checked as in the attached picture.
Since you say it works about half the time, of course, please repeat enough times to get a few failures.
For my f/5.6 refractor with an ASI1600, I use 2x2 bins, gain of 200 and 3-5s exposure depending on the filter.
Appreciate your help in getting me to get this right,
Jo--There's a checkbox to suspend guiding (see the bottom line of the attached picture of the focus tab). If it's unchecked, it will not suspend guiding.
Pit--I noticed that in the Ekos options, under Capture (see the 2nd attachment), there's a "Guiding Settle" parameter that defaults to 0. Would that solve, or at least mitigate, your issue?
I too have an OAG, but the focus does seem to work with the guider active. I worried about what you were saying, though, which was the reason for this thread.
I have since switched to suspending the guiding during AF, and expanded the Phd2 window to 25x25 pixels, and things seem to work as well, and I guess it makes more sense.
It probably wouldn't be hard to put in a "stall N seconds after autofocus" if you thought that would be useful.