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INDI Library v2.0.6 is Released (02 Feb 2024)

Bi-monthly release with minor bug fixes and improvements

INDI focuser driver for Waveshare Stepper Motor HAT for Raspberry Pi / Rock Pi

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I still want to go head-to-head with your design.

Identical optical train, so it's just the focuser.

We got to have a competition, Eric!!!

:-)

Best, Jo
3 years 10 months ago #54524

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I win, been there done that :) I hate Helical's
Last edit: 3 years 10 months ago by Clive Garner.
3 years 10 months ago #54525
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    redcat.avi

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That is cool! The key is the tension pulley. That makes all the difference for eliminating backlash, I bet.
Alright, you can be part of the Olympiad here.
I am not chickening out. I am still confident I will win.
:-)
Jo
3 years 10 months ago #54526

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Already tested, and it worked a treat, the last pic is of Rho, having used full autofocusing
Last edit: 3 years 10 months ago by Clive Garner.
3 years 10 months ago #54527
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Very nice! Just curious, what are using to control the stepper motor? The Waveshare HAT, or some other (possibly Arduino) controller?
3 years 10 months ago #54528

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Yes, very nice! I think as far as accurate focus is concerned, this may come to a draw. This is what I got from the middle of a large metro area (Dallas), Bortle 8/9, and with an inferior mount (iOptron SmartEQPro+; RMS 4+, 7 arcsec/pixel).



Not nearly as nice as yours, editing not yet completed, needs more narrowband, but this is about focusing. The focusing routine (linear, automated and repeated hourly through the night) was posted earlier in this thread.
Last edit: 3 years 10 months ago by Jose Corazon.
3 years 10 months ago #54532
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The focused worked much better last night. I now get the expected V / curve during auto focus. I could repeatably move focus away from the focus point and back to the same step number and things were in sharp focus. I still need to tune the parameters for the auto focus algorithm itself. It was never able get it to automatically choose the focus point (though I was able to choose it myself based on the data from the auto focus process). I’m using the linear focus algorithm. Once it finishes the first pass, it then appears to try to take multiple readings at the same steps right around the focus point. However my seeing must be varying enough that it couldn’t get consistent enough readings without moving the focuser and would eventually error out. I adjusted the tolerance % without success, though I’m not sure that’s the right parameter. I didn’t spend a lot of time as I wanted to get started imaging, so I just chose the best focus point and moved on.
3 years 10 months ago #54558

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Congrats on the progress! :)

For myself, auto selecting a single focus point has never been reliable. I either need to manually select a single point, or use full field mode. Full field mode is the method I use now. You can even tell it to limit itself to the central part of the image, if you prefer.

I use the polynomial focus method. It seems to work well enough. I never tried the linear. I might give that a try. Some people say it works better.
3 years 10 months ago #54565

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I have always used Full Field mode. Set tolerance to 5%. Much depends on the initial step size with the linear focuser. If that is too large, it may miss the minimum. But once established for a specific focuser and telescope, it will hit the optimal focus every time.

If you have NO backlash, polynomial may be better, because step size will continuously decrease while converging upon the minimum. But if there is ANY backlash in your system, linear will be more consistent and reliable IME.
3 years 10 months ago #54566

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Thanks for the advice everybody. Full Field mode worked *great* last night! It was bang on and worked the first time. Linear worked just the way that I would expect it to. I even tried polynomial mode and it picked the same focus point as Linear, though it didn't seem like it took enough data points to come to that conclusion. I'll have to play around with it more before I put my trust in it.

Woot! I'm really happy with how things are working. I'll still probably switch to the 5:1 stepper at some point, but I'm not in a hurry.
3 years 10 months ago #54640

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Sweet! Another satisfied customer! :)

Sounds like you might not need the geared stepper.
3 years 10 months ago #54642

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Its not needed, but it might provide some additional resolution, though it remains to be seen whether the mechanics of the RedCat or my seeing conditions lend themselves to improvement.
3 years 10 months ago #54643

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