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INDI Library v1.9.8 Released (Yesterday)

Bi-monthly INDI Library released with new drivers and bug fixes.

For those with focus issues

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Hy and Jo,
I really wasn't attacking what you have done. I think it's great. In fact, now I know it does a polynomial fit I'm tempted to use it because I think that moving in one direction will give better data, even with minimal backlash.

It's just that with an absolute focuser once the best focus position has been found using the polynomial I'd like to move straight there. It's not critical though, I could live with it as is or stay with the current polynomial.

Chris
2 years 7 months ago #48984

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Chris,
I absolutely didn't take your comments as an attack, quite the opposite. Sorry if my response sounded like that.
I agree that if polynomial gives you good results, it should be quicker so you'd be well served using it.
It was my understanding that there were some people that were having issues with the current AF algorithms, especially SCT owners,
(though quite honestly my configuration also sometime seemed sub-optimal) so I targeted a "slow and steady" approach for those folks.
AP1100 & Orion Atlas Pro, WO/ZS105 w/Moonlight V2 focus, GSO RC10 w/RSF focus
ZWO ASI1600, Astronomik Filters, ST80, QHY 5L-IIm.
KStars/Ekos/Indi on NUC10 & RPi4 w/SSD -- Ubuntu
Projects: Greedy Scheduler, Terrain, Polar Align, Analyze, Linear Focuser, SEP MultiStar & GPG Guide, FITS autostretch.
The following user(s) said Thank You: Jose Corazon
2 years 7 months ago #48985

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I also did not read this as undue criticism of Hy's great contribution at all! On the contrary, we all need constructive criticism if we want to improve. Seeing a way for someone to improve and not telling defeats the purpose.

Keep it coming, Chris!

Best

Jo
Atlas Pro AZ-EQ, ASI1600MM-Pro, ASI120MM-S, ES102ED, WO-Z61, Nikon D3300, ASI-EFW, ZWO LRGB,Ha,O3,S2 filter set
2 years 7 months ago #48992

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I have now had the chance to use Hy's Linear v3.2 algorithm for several nights and I am pleased to report that it performs flawlessly with my simple analog FCUSB driven home-built focuser in a heavily light-polluted area, so under the worst possible conditions.
It finds the optimal focus every time and the U-curve that is being displayed gives me visual confirmation that the focuser has indeed found the minimum.
I definitely will use this method as my standard focusing method from now on.
Chris, you may want to try this, too. It is definitely better and more consistent than the "polynomial" back and forth method.
Atlas Pro AZ-EQ, ASI1600MM-Pro, ASI120MM-S, ES102ED, WO-Z61, Nikon D3300, ASI-EFW, ZWO LRGB,Ha,O3,S2 filter set
2 years 7 months ago #49165

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Replied by Giles on topic For those with focus issues

I did try this last night, but didn't really understand how it worked and went about setting silly parameter values trying to understand it.

I will try this driver at the next outing with sane parameters (I have a DC motor, not a stepper motor - so this might work better for me, my imaging train weight and poor stock focuser / focuser control means that retracting the tube is tons slower than extracting).

Unfortunately UK weather does not look good for at least another week.
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I blog my progress: www.coochey.net
2 years 7 months ago #49167

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I also use exclusively analog DC motors and the weight is not really an issue. There is a very simple solution for that: I counterbalance the weight of the tube and camera with rubber bands that pull on the tube and so take the strain off the focuser. Very simple, but effective. You can completely neutralize the weight of the camera and the tube that way.
Atlas Pro AZ-EQ, ASI1600MM-Pro, ASI120MM-S, ES102ED, WO-Z61, Nikon D3300, ASI-EFW, ZWO LRGB,Ha,O3,S2 filter set
The following user(s) said Thank You: Giles
2 years 7 months ago #49169

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Replied by Giles on topic For those with focus issues


I think I saw your picture of this earlier in the thread, it is something I will try. I hope to eventually move to a better focuser with a stepper controller, e.g. the Primulace Sesto Senso or similar.
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I blog my progress: www.coochey.net
2 years 7 months ago #49170

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I honestly don't see the need to move to a different focuser system. My analog focusers driven by FCUSB work GREAT. The result using the Linear v3.2 algorithm is optimal as is, I cannot see how any expensive commercial focuser could possibly do better.

My limitations are in the optics and the location (light-polluted inner city), not with my analog focusers.
Atlas Pro AZ-EQ, ASI1600MM-Pro, ASI120MM-S, ES102ED, WO-Z61, Nikon D3300, ASI-EFW, ZWO LRGB,Ha,O3,S2 filter set
2 years 7 months ago #49178

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Replied by S on topic For those with focus issues

Finally some nice weather and I was able to test the new algorithm. I turns out that I also previously has a problem with my coma corrector so I have now switched to another one. This did wonders on the focusing and my curves are no longer very flat near the bottom but actually looks more V-shaped. After fixing this issue, all algorithms in EKOS actually seems to work OK, including Linear. I also identified that I might have some kind of slip in my focusing system, so next step is to fix this and hopefully focusing will be very reliable. So in total, it seems that most of my problems with focusing was related to both optics and mechanics. I look forward to trying out the linear algorithm more when I fix my remaining mechanical issues.

As I general note, it seems to me that indi/ekos/kstars have become much more stable during the last year. Great work to all the coders out there :-)
2 years 6 months ago #50754

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Replied by Alfred on topic For those with focus issues

Yesterday I finally got to run an Ekos session and for the first time ever I did use the linear focus mode. From the very start it did perform flawlessly and IMO it reliably achieved the best possible focus position. I tested with two self-made stepper motors driven by a Robofocus compatible controller. Excellent work, Hy, thanks an awful lot!
2 years 6 months ago #50766

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Replied by S on topic For those with focus issues

Hi!

I still can't get autofocus to work reliably. After fixing some mechanical and optical problems it is much better than before, but only works in say 50% of the time and this applies to all algorithms. In 100% of the time I can focus manually using the in and out buttons. Here is an example where the linear algorithm gave an error:

The algorithm continued to move the focuser the wrong way until it was so out of focus and could not detect any stars and gave an error.

Here are some other things that seems to mess with all the algorithms:

1. The HFR values calculated are very noisy in general, and I imagine it can be hard to focus with noisy values. I use 'auto star' and 'full field'. Maybe one should be able to choose also the minimum or maximum HFR instead of the average?

2. The star locater is sometimes locating non-stars, which messes up the HFR value. This can be e.g. hot pixels, edges of dust motes, edges of the CCD (my CCD for some reason give a black border around the whole image). I have tried all star detection algorithm and can't seem to get reliable results.

3. If image is far from focus, the star detection detects sometimes the edges of the donut-star-image produced by a Newtonian telescope and most often it does not detect the donut-start-images.

I have now ordered a ZWO EAF, which I hope will improve upon my FCUSB+DC AccuFocus motor, but all helps is appreciated since I imagine the EAF might not solve all problems for me...

Best Regards,
Søren
2 years 6 months ago #51069
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Søren,

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

Notes:
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,
Hy
AP1100 & Orion Atlas Pro, WO/ZS105 w/Moonlight V2 focus, GSO RC10 w/RSF focus
ZWO ASI1600, Astronomik Filters, ST80, QHY 5L-IIm.
KStars/Ekos/Indi on NUC10 & RPi4 w/SSD -- Ubuntu
Projects: Greedy Scheduler, Terrain, Polar Align, Analyze, Linear Focuser, SEP MultiStar & GPG Guide, FITS autostretch.
2 years 6 months ago #51076
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