Re:Suggestions for Focus module

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Suggestions for Focus module was created by Lead_weight

Since 3.0, I’ve been imaging with quite a few sequences, and have seen some repeated issues crop up with focusing.

I’ve seen the Focuser system automatically select stars in the corners multiple times. This is certainly a poor choice if you have any off axis issues like tilt, or if you have coma in the corners that needs to be cropped out. It should try to pick stars within a center circle area of the image.

Secondly It can tend to grab rather large stars. If you’re imaging with an RC and you have diffraction spikes, this creates some issues on the focusing module knowing what is the best FWHM for that star. Alternatively I’ve seen it pick extremely small 1-2 pixel stars, then easily lose the star as the focusing routine starts. Seems the best option is to pick stars between an FWHM of 2-6 and anything outside of that size should be discarded. Of course, this might make things challenging if someone starts the focus routine out of focus. So maybe there are several steps where it picks any star first regardless of FWHM to try to get it in rough focus first, then it moves on to a star with an FWHM of 2-6 to ensure focus is accurate. This to me would be way more reliable.
-Andrew
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2 weeks 1 day ago #33438

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Replied by phomer60 on topic Suggestions for Focus module

Andrew,
I am glad that someone else has also noticed some unusual focusing behavior.
If I let the software select a star it always selects one near the upper left corner, fairly close to the edge. I would prefer that it selected one about a third of the way from the centre, if possible, to maximise the focus for the entire frame.
I think it is selecting one with an appropriate brightness so I am not be seing the second part of your issue.
Paul
2 weeks 1 day ago #33445

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Replied by TallFurryMan on topic Re:Suggestions for Focus module

Alternately, you can use the full frame focusing option. It will smooth out the specificities of the frame by averaging the HFR of the detected sources. However, it is slower eventually (5-10 seconds lock-up on a 1.6GHz monocore for a 1Kx1K frame) and less stable than a single-star procedure. A compromise for an all-round automation perhaps.

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Last edit: 2 weeks 1 day ago by TallFurryMan.
2 weeks 1 day ago #33453

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Replied by Christian on topic Suggestions for Focus module

+1 for the first proposal.
2 weeks 23 hours ago #33471

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Replied by dokeeffe on topic Re:Suggestions for Focus module

+1 for the full frame focus option. I get much better results with it. Its a bit slower but not much for me (although I'm using an i5 quadcore desktop)
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2 weeks 23 hours ago #33473

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Replied by mikefulb on topic Suggestions for Focus module

I would encourage also providing hooks for a third party focus routine to be run during a sequence. I've been working on something and at the moment I just use it with some code I've thrown together for data collection. I tried running it as a script between frames during a sequence but the way EKOS pretty much assumes any BLOBs are for it during a sequence (even when a script is run) when the external autrofocus software started taking frames they were captured and written out as sequence images by EKOS.

I think having EKOS act more as a director of a symphony of tools (astrometry.net, PHD2, external autofocus, etc) would be better than locking up useful tools in the EKOS framework. This has been a real boon for the Windows/ASCOM world as there are tons of programs (ACP, Voyager, SGP, etc) that can be used to automate imaging and each one doesn't have to reinvent all the parts each time.
2 weeks 23 hours ago #33475

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Replied by Herrhausen on topic Suggestions for Focus module

+1 for first proposal which is reasonable and would clearly improve reliability IMO.
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2 weeks 20 hours ago #33476

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Replied by phomer60 on topic Re:Suggestions for Focus module

Although there are some advantages with the Full Frame option the download speed is a killer for me - approx 20-40 seconds depending on which camera I have. Having a faster CPU makes very little difference.
If you are attempting focus with Narrowband filters you need significantly longer exposures to have a star, which makes it worse.
Paul
2 weeks 18 hours ago #33477

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