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INDI Library v1.9.6 Released (21 May 2022)

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

Tips for Auto-Focus

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Replied by Peter Kennett on topic Tips for Auto-Focus

I have the Esatto focuser on a C11 EdgeHD at f.7.
I suspect there is a backlash issue as the initial three measurements jump wildly until the focuser starts its run inward.  Then they all seem smooth along the curve.  I don't know if the Esatto has a backlash issue, but if it dos, EKOS has that setting greyed out.

My second issue is that I can't consistently achieve stable HFR numbers.  For example, if I keep the focuser still, and just take 3 measurements back-to-back at the same spot,  I can get HFR numbers that vary as much as 0.3.   I can get measurements like 2.34, 2.56, 2.41, 2.25 etc…. I tried short and long exposures, I tried averaging - nothing seems to help much. 

Peter
 

iOptron CEM120 EC2 and CEM25P
Celestron C11 EdgeHD
William Optics Star71
ASI 1600Mm Pro, ASI 462MC
Moonlight motorfocus & Esatto focuser
LodeStar X2 and ZWO OAG
DewBuster
NANO PC-T4
1 year 3 months ago #68621

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Replied by S on topic Tips for Auto-Focus

My hfr values also jump around and i suspect it is just the seeing. They generally jump much more that what your show. Longer exposures seems to stabilize them a bit, i think i currently use 5s for focusing.
1 year 3 months ago #68627

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Replied by Doug S on topic Tips for Auto-Focus

Hi Peter, Could the issue you see with the first measurements might be related to a slight wobble in the focus mechanism? In my Rev1 RASA, I have seen what looks like an initial "hump" in the first couple of measurements before the inward push settles down into the v curve shape. I do think your variance could easily be explained by seeing too. I'm just wondering if your initial steps are a "feature" of Celestron's focus mechanisms on the Edge & RASA configs.... I have found that a well seeded autofocus start helps to eliminate that hump. Just a thought...
RASA11, Celestron CGX-L, ASI183mc Pro, 60mm guider + ASI290mm mini, ASI EAF focuser, PPB, Rpi4-4Gb+SSD, Powered USB3 hub, hardwire Ethernet.
1 year 3 months ago #68639

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Replied by Peter Kennett on topic Tips for Auto-Focus

DM, it's not the built-in focuser since I don't use it. The Esatto is like a Moonlight - it is its own focuser and does not attach to the built-in one. I am able to adjust the focus WHILE guiding with an OAG and not see the guide star shift more than 0.2 arc seconds during the focuser movement. It's crazy stable and has 440,000 steps.

Seeing is certainly an issue. But the fact that the large errors occur at the beginning of the focus routine makes me wonder about backlash - but I don't even know if the focuser has any. It's a new focuser and I've not met anyone with one on a large scope.

I do a manual focus at the beginning, so I start with a good sharp focus. But the auto focus routine doesn't maintain it.  In fact, even when I clearly see the calculated best focus (yellow line) - which is always vey good - the very last step in the autofocus routine never chooses it. Instead, it stops at some point where the HFR value reversed and assumes that this was the best spot. But it almost never is. Even when I can clearly see the perfect calculated focus - the routine chooses something worse in the end.
 

iOptron CEM120 EC2 and CEM25P
Celestron C11 EdgeHD
William Optics Star71
ASI 1600Mm Pro, ASI 462MC
Moonlight motorfocus & Esatto focuser
LodeStar X2 and ZWO OAG
DewBuster
NANO PC-T4
Last edit: 1 year 3 months ago by Peter Kennett.
1 year 3 months ago #68642

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Replied by Doug S on topic Tips for Auto-Focus

Not sure if you're talking about linear focus....I think you are. If so, yes, that last/final resting spot is a problem. I've fixed that in my code, and sent a request to Hy to fix it. The issue is that if the last HFR reading is within the tolerance zone, and that reading rises above the one just prior to it, then the routine stops right there. I've watched this with frustration since Linear was created. I can say that in my modified version (which I'll gladly share with anyone who wants it...just a couple lines of code), the final resting place is the polycurve minimum as long as it's still in the "inward" direction. That choice honors/preserves the work that was done in gathering all HFR samples...not just the last one (which is most likely to be affected by seeing). I don't suffer that any more! I always get a better V curve answer now...I'm VERY happy with it now. Hopefully Hy will act on that suggestion (or I may submit it as part of AFC that's coming). Cheers, Doug
RASA11, Celestron CGX-L, ASI183mc Pro, 60mm guider + ASI290mm mini, ASI EAF focuser, PPB, Rpi4-4Gb+SSD, Powered USB3 hub, hardwire Ethernet.
1 year 3 months ago #68645

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Replied by Peter Kennett on topic Tips for Auto-Focus

That's it! The resting spot in Linear Focus stops in the wrong spot almost all the time. I verify this by examining a sub after autofocus, and then I manually set the focuser to the calculated poly curve spot. After the next exposure I compare and the poly curve one always better. It's crazy because EKOS is the one that calculated the correct spot - leaves it on the display for all to see - but then chooses the wrong spot to set the focuser.

I would LOVE to have your modded version of the code, but I do not know how to add your code to my system.

iOptron CEM120 EC2 and CEM25P
Celestron C11 EdgeHD
William Optics Star71
ASI 1600Mm Pro, ASI 462MC
Moonlight motorfocus & Esatto focuser
LodeStar X2 and ZWO OAG
DewBuster
NANO PC-T4
1 year 3 months ago #68647

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Replied by Doug S on topic Tips for Auto-Focus

Hi Peter, I'm working behind the scenes with a few folks to see if progress can't be made to fix this for the benefit of everyone. Stay tuned.... cheers, Doug
RASA11, Celestron CGX-L, ASI183mc Pro, 60mm guider + ASI290mm mini, ASI EAF focuser, PPB, Rpi4-4Gb+SSD, Powered USB3 hub, hardwire Ethernet.
The following user(s) said Thank You: Jack, Eric, Peter Kennett, Spartacus, Stefan
1 year 3 months ago #68661

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Replied by Peter Kennett on topic Tips for Auto-Focus

Hello Doug. Has there been any movement of incorporating your changes into EKOS?
I have the latest Stellarmate running and the issue is still there. I have to manually adjust the focus after EKOS chooses the wrong final value.

iOptron CEM120 EC2 and CEM25P
Celestron C11 EdgeHD
William Optics Star71
ASI 1600Mm Pro, ASI 462MC
Moonlight motorfocus & Esatto focuser
LodeStar X2 and ZWO OAG
DewBuster
NANO PC-T4
9 months 1 week ago #75734

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Replied by Doug S on topic Tips for Auto-Focus

Hi Peter, to make a long story short, this fix for the polynomial minimum in the linear algorithm did not move into the baseline code, but I have been using it in my code baseline very successfully ever since it was developed. I also have been using Adaptive Focus Control (AFC) which minimizes need for autofocus runs (it only requires a temperature sensor). I have the code up-to-date as of the nightly 3.5.6 from a week ago.

The pain trade here is that because the code never became part of the Ekos baseline, you need to merge it for any update you want to pull. It's not horrible, but there's that to consider. For me, I probably wouldn't even have updated to 3.5.6 if it hadn't been the case that 3.5.4 Indi had a problem with the Celestron GPS driver (swapped axes senses which thwarted polar alignment). To get that bug fixed, I needed to update & merge. So, never say never, but unless something very important comes out in future releases, I probably will give up on Ekos upgrades from here forward. I can do all I want with the latest baseline. From what I've seen as I merged my code this last time, there's at least some question as to whether changes being made are necessary, or if there's just developer "tinkering" happening. Tinkering is normal for aging code, but eventually it makes code less stable IMO. Regardless, if you want the code as of 3.5.6, send me a PM with an email contact and I'll send you both the AFC code and the fix for linear focus completion. CS Doug
RASA11, Celestron CGX-L, ASI183mc Pro, 60mm guider + ASI290mm mini, ASI EAF focuser, PPB, Rpi4-4Gb+SSD, Powered USB3 hub, hardwire Ethernet.
The following user(s) said Thank You: Sonny Cavazos
9 months 1 week ago #75755

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Replied by Sonny Cavazos on topic Tips for Auto-Focus

Yes, I have the same issue. I hope the fix gets integrated into the main code.
9 months 1 week ago #75767

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Replied by Peter Kennett on topic Tips for Auto-Focus

That's strange that it isn't being adapter by the rest of the EKOS team. Are we the only ones who have this issue?
Right now, it makes auto focus completely unusable. I have to stay up all night and monitor the focus manually.

Anyway, I would LOVE to have your fix, but as I am not a programmer I am afraid that I would have no idea how to install it. If you have step by step baby instructions - I could manage though.

Peter

iOptron CEM120 EC2 and CEM25P
Celestron C11 EdgeHD
William Optics Star71
ASI 1600Mm Pro, ASI 462MC
Moonlight motorfocus & Esatto focuser
LodeStar X2 and ZWO OAG
DewBuster
NANO PC-T4
9 months 1 week ago #75771

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Replied by Doug S on topic Tips for Auto-Focus

Sorry Peter....I thought you had a development environment. Unfortunately, I think you and Sonny (and whomever else) will need to try to convince Jasem to finally address this bug. I thought for a minute I had convinced him, but nothing changed. The developer doesn't understand basic principles of polynomial function development over many seeing impacted HFR measurements. He actually strongly believes that a last (defective) measurement in the set should outweigh all prior measurements! Too hard to argue with logic formed like that. I wish you better luck in convincing otherwise (if you want to see progress). In the worst case, if nothing changes, you might consider biting the bullet, getting a spare PI, and then using Jerry Black's script to build your own code baseline. You'd then be able to get the simple fix and put the whole misery behind you... Send me email if you get to that point. Until then, I feel your pain.... (-:

Cheers, Doug
RASA11, Celestron CGX-L, ASI183mc Pro, 60mm guider + ASI290mm mini, ASI EAF focuser, PPB, Rpi4-4Gb+SSD, Powered USB3 hub, hardwire Ethernet.
Last edit: 9 months 1 week ago by Doug S.
9 months 1 week ago #75772

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