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What parameters to use in autofocus in NINA

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#1 EEBA

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Posted 23 September 2021 - 04:20 AM

Hi folks, I invested money in 2 focusers for some of my rigs. I have been using them for a few months and I think I need to master this because I don’t enjoy it. It is suppose to make things simpler and faster , but I think I spend more time now than before I had them. I I have a moon lite in my edge 800 with locked mirrors and a ZWO AEF in my radian raptor. Let’s focus tonight in my moon lite and my edge . I noticed I get bad curves like seesaw and sometimes get a fail message. My focal length is 2032 mm. And I I’m using overshoot 150. Exposure 10 seconds. Step size 10 initial offset 4 Binnin 1.
Ah , I image with ZWO 533mc.
Any advice how to change to parameters I need?

#2 Sean1980

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Posted 23 September 2021 - 05:22 AM

First suggestion head over to the NINA discord. 4 steps offset I think should be higher for a reflector if I recall correctly like 6, not sure about step size. It’s also important that you are already close to focus before starting the AF routine. And look at the HFR change when doing the initial offset should be large enough for a good measurement. My focus is good at 4 and with my stepsize and offset the first measure point is 12 which gives a nice curve

#3 EEBA

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Posted 23 September 2021 - 05:32 AM

First suggestion head over to the NINA discord. 4 steps offset I think should be higher for a reflector if I recall correctly like 6, not sure about step size. It’s also important that you are already close to focus before starting the AF routine. And look at the HFR change when doing the initial offset should be large enough for a good measurement. My focus is good at 4 and with my stepsize and offset the first measure point is 12 which gives a nice curve


I want aware o outNINA discord. I’ll take a look .anyway, I have an SCT 8inch no a reflector

#4 Sean1980

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Posted 23 September 2021 - 05:37 AM

I want aware o outNINA discord. I’ll take a look .anyway, I have an SCT 8inch no a reflector

Ah read over that think the same is true for offset of an SCT. But someone on the discord must have a similar setup
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#5 OldManSky

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Posted 23 September 2021 - 08:04 AM

I want aware o outNINA discord. I’ll take a look .anyway, I have an SCT 8inch no a reflector

Um, an SCT *is* a reflector... :)

 

Check out Cuiv's video on setting up NINA autofocus for some help configuring it:  https://www.youtube....h?v=XsjT-We9Wn0


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#6 sbharrat

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Posted 23 September 2021 - 08:18 AM

Um, an SCT *is* a reflector... smile.gif

 

Check out Cuiv's video on setting up NINA autofocus for some help configuring it:  https://www.youtube....h?v=XsjT-We9Wn0

 

I want aware o outNINA discord. I’ll take a look .anyway, I have an SCT 8inch no a reflector

Definitely check in to the autofocus-support section of the NINA Discord channel. You can find some pinned videos there. The following is helpful in trying to set the initial step size

https://www.youtube....h?v=lHrfaR7A0L0



#7 EEBA

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Posted 23 September 2021 - 04:20 PM

Thanks all , waiting
For the night to test new settings:)

#8 SnowWolf

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Posted 23 September 2021 - 11:10 PM

I have an Edge 800 and the Moonlite focuser.  

 

Here are my NINA autofocus settings:

 

Step size - 50 (this is the full step size in the Moonlight controller, not half step)

Exposure - LRGB - 8 seconds, Narrowband - 12 seconds (this will be specific to your camera and filters)

Initial offset steps - 5

AF method - Star HFR

Curve fitting - parabolic

Focuser settle time - 1

Attempts - 1

Frames per point - 1

Use brightest stars - 0

Inner crop ratio - 1

Outer crop ratio - 1

Backlash compensation method - Absolute

Binning - 1

Backlash in/out - 0/0

 

I have to start near focus - plus/minus 200 steps.  Then it works well.

 

Edit:

 

You need much more movement to start than 40 steps.


Edited by SnowWolf, 23 September 2021 - 11:11 PM.


#9 Splurk

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Posted 24 September 2021 - 12:27 AM

I just started using my first electronic focuser two days ago. I quickly learnt to set the step size to 150 while keeping just 4 initial offset steps. I found the micro steps of 10-50 just no good and I didnt get a good V shape. 

It will then estimate the likely best focus position based on the curve and check it against the original focus position.



#10 EEBA

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Posted 24 September 2021 - 12:34 AM

I have an Edge 800 and the Moonlite focuser.

Here are my NINA autofocus settings:

Step size - 50 (this is the full step size in the Moonlight controller, not half step)
Exposure - LRGB - 8 seconds, Narrowband - 12 seconds (this will be specific to your camera and filters)
Initial offset steps - 5
AF method - Star HFR
Curve fitting - parabolic
Focuser settle time - 1
Attempts - 1
Frames per point - 1
Use brightest stars - 0
Inner crop ratio - 1
Outer crop ratio - 1
Backlash compensation method - Absolute
Binning - 1
Backlash in/out - 0/0

I have to start near focus - plus/minus 200 steps. Then it works well.

Edit:

You need much more movement to start than 40 steps.


Thank you snow wolf, as I type I am putting the settings in my rig . It is smoke around because a fire, but. I am trying. My only question is no backlash? I believe my image train has some backlash. Is not an issue?

#11 SnowWolf

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Posted 24 September 2021 - 01:17 AM

Thank you snow wolf, as I type I am putting the settings in my rig . It is smoke around because a fire, but. I am trying. My only question is no backlash? I believe my image train has some backlash. Is not an issue?

I measured my focuser with a dial indicator.  Moving out 1000 steps in 100 step increments and back came within .0005" (.0127mm).   Close enough to 0 for me.

 

I fiddled with backlash numbers in NINA with the Moonlite focuser on my refractor and found that if I had any set, the in focus "number" tended to drift over time.  So that, by the end of a month, the position numbers had changed by 1000 steps, but the actual position hadn't changed.  Changing the backlash to 0 fixed that.  I just kept that setting when I got the focuser for the Edge and it has worked OK.

 

Edit(again):

I just did some calculations - the critical focus depth for the Edge 8 is, depending on wavelength, around .25mm.  Each step with the Moonlite focuser is around .004mm.  That means you need to be in a window of about 50 steps. The small backlash won't matter much.

 

Info about critical focus depth:

 

https://www.youtube....annel=JamesLamb


Edited by SnowWolf, 24 September 2021 - 01:38 AM.


#12 Juno18

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Posted 24 September 2021 - 02:11 AM

For me, setting up the EAF (ASI EAF was pretty easy imaging at a fl of 571mm and 270mm using two different scopes. I would think that focus is more critical as the fl increases.

 

After you use the settings above, look at the result. I use a hyperbolic curve. I like that type of result curve. Example below of my somewhat rough AF routine in N.I.N.A. (the only image that I had).

 

NINA Autofocus Result.JPG

 

My apologies for the fairly poor AF curve. Even being rough around the edges, the repeatability is excellent.

 

Once you try out the settings, look for flat spots in the beginning of the curve. It will indicate insufficient backlash settings (overshoot). Try increasing that setting if you see a flat or erratic beginning to the hyperbolic curve.

 

Good luck and post your results!



#13 Wilsil

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Posted 24 September 2021 - 02:52 AM

I used Amy's Utube video to calculate my step size.

Find the resolution of your focuser.

Find the critical focus zone (CFZ) of your filter/camera/scope combination.

Step size = CFZ / focuser step size.

I used 1.5 to 2 x step size and came with my Esatto to 6000.



#14 EEBA

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Posted 24 September 2021 - 06:02 AM

I watched both videos, the James lamb is very scientific, lol but interesting. I followed Amy’s video to find cfz and step size . I followed exactly what she did . And it came out my step size should be 90 low end and 120 high end. She used a 650 mm focal length refractor. I am not sure all this applies to SCT. Where minor touches to to the focuser can sent you quickly out of focus, anyway, I tried low and high end step sizes and they both appear to be too large because after I set my off set of 5, the first number on the focuser goes way too far out of focus . About 500 steps to the right. In my SCT 500 steps make the initial close to focus stars huge donuts . I’m still researching in NINA forum for answers. So far still trying to find good settings.
PD . I was thinking the focuser was not in the center of the draw tube, but I measure total travel length (3000 steps) put in the center. Focus with SCT original focus and tight again the knows of lockers mirror. No difference after this.

#15 dghent

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Posted 24 September 2021 - 07:29 AM

It takes some experimentation to determine the best step size as that is governed by your focuser’s mechanical properties in conjunction with aspects such as your particular setup’s focal ratio. Secondary aspects are things such as your camera’s sensitivity (AF exposure time) and how corrected the light cone is when it reaches your sensor (whether you will want an inner crop ratio amount or not)

You can take the AF log files that NINA produces and drop them into the #autofocus-support channel in the NINA Discord chat server. The bot there will analyze it and give some suggestions if any suggestions are warranted. It will also let more experienced people see what you’re actually getting and help you in adjusting the settings.
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#16 SnowWolf

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Posted 24 September 2021 - 03:13 PM

I watched both videos, the James lamb is very scientific, lol but interesting. I followed Amy’s video to find cfz and step size . I followed exactly what she did . And it came out my step size should be 90 low end and 120 high end. She used a 650 mm focal length refractor. I am not sure all this applies to SCT. Where minor touches to to the focuser can sent you quickly out of focus, anyway, I tried low and high end step sizes and they both appear to be too large because after I set my off set of 5, the first number on the focuser goes way too far out of focus . About 500 steps to the right. In my SCT 500 steps make the initial close to focus stars huge donuts . I’m still researching in NINA forum for answers. So far still trying to find good settings.
PD . I was thinking the focuser was not in the center of the draw tube, but I measure total travel length (3000 steps) put in the center. Focus with SCT original focus and tight again the knows of lockers mirror. No difference after this.

I think, as you found out, even 90 steps is too big.  

 

You're ASI33 has nearly the same pixel size as my ASI1600, so the numbers I get should be comparable to yours.

 

I start with a close focus - HFR below 6, below 5.5 is even better, depending on seeing..  During autofocus, NINA moves out 250 steps total (5 x 50).  The HFR grows to around 10-12. Each move in gets a lower HFR until it gets down to the high 3's on very good seeing nights to the low 5s on not so good seeing.  Then, as it moves further in (another 5 or 6 points),  it goes back up to the 10-12 range.

 

You're starting in the middle of the travel is good.




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