ZWO EAF

[ninjageezer]

I have been looking at my focus runs and although most seem to get to about .99 of the Hyperbolic R value the curve seems a bit erratic .I have spent ages adjust backlash and step size and just when you think its spot on you get some strange curves.my question is should I set the backlash in the driver or in NINA or both ?? I had a dabble with Hocus focus and that made things worse.

I also tried 3 and 4 offset steps as in the pictures.

the EAF is the latest ZWO version.

 

 

[StevieDvd]

Have a read of this thread NINA Backlash video on YT as it has a lot of info, including on NINA auto focusing backlash. I found the link in there very informative, as I posted in the thread.🙂

[scotty38]

For what it's worth these are my settings. I've tried different but always come back to these and they seem to work for me...

[Richard_]

Another good source is Patriot Astro per the video below. He uses the ZWO EAF as an example and it might be worth checking that out. 

Looking at your second pic, it looks like you still have some backlash since the points on the night aren't straight. 

The biggest improvement I saw was the changing of the Curve Fitting Strategy and the Backlash Compensation Method, as explained in the video. For backlash, its really important to put a value for either in or out and leave the other as zero (just like the image shared by  @scotty38). If you put values in both, you will get problems. 

 

 

[ninjageezer]

Ok so finally got a lovely clear sky last night, spent the first hour trying to get the EAF curve decent which I finally did. Then when the 2 hour mark came and NINA did its autofocus run it kept failing even though I had not changed anything ,so then I spent another 40 mins trying to sort the focus out again.

when I finished imaging I thought I would try the EAF again and yes it failed so today I want to try and get to the bottom of the issue .I have tried different step sizes different backlash settings and even changed the exposure times as I'm using an optolong L extreme filter at the moment.

I have tried exposure times from 7 to 12 seconds.

last year when I got this ZWO EAF it seemed to work fine when I hade it on the same scope I have a new camera now that's all. I think my first job is to check all the screws are nice and tight to make sure I have no slip ,I cannot seem to repeat a good curve ,just when I think ive cracked it the next run is bad.

i did try setting the backlash in the driver also ,this made no difference . the image on the bottom is typical of what would happen ...always the last part went off Course if this helps.

 

 

 

Edited January 17, 2023 by ninjageezer

[Richard_]

9 hours ago, ninjageezer said:

Ok so finally got a lovely clear sky last night, spent the first hour trying to get the EAF curve decent which I finally did. Then when the 2 hour mark came and NINA did its autofocus run it kept failing even though I had not changed anything ,so then I spent another 40 mins trying to sort the focus out again.

when I finished imaging I thought I would try the EAF again and yes it failed so today I want to try and get to the bottom of the issue .I have tried different step sizes different backlash settings and even changed the exposure times as I'm using an optolong L extreme filter at the moment.

I have tried exposure times from 7 to 12 seconds.

last year when I got this ZWO EAF it seemed to work fine when I hade it on the same scope I have a new camera now that's all. I think my first job is to check all the screws are nice and tight to make sure I have no slip ,I cannot seem to repeat a good curve ,just when I think ive cracked it the next run is bad.

i did try setting the backlash in the driver also ,this made no difference . the image on the bottom is typical of what would happen ...always the last part went off Course if this helps.

Those are some pretty high HFR values on the Y-axis of your charts. With my refractors (FLT120 and Redcat51), the chart falls over at HFR values above ~15, as is the case in your second image. Was this the lowest step size you tried? What is your tolerance for R2? 

Do you get these issues when you do not use the l-extreme filter (ie no filter or even a UV-IR filter)? 

[knobby]

Also, check the flexible coupling is not over stretched, it works better when almost closed if that makes sense.

If it's pulled open you'll get random uneven backlash.

[ninjageezer]

 

I spent ages last night trying to fine tune the settings in NINA, sometimes not always, the first run is poor or fails the second attempt normally good .99 this is after a lot of fine tuning.

I double checked everything was tight on all the grub screws etc on the EAF all looks good there nothing catching or rubbing .these are the settings I finished off with ,I am open to any suggestions.

the flexible coupling looks ok very even fine gaps does not look overstretched ,will get a photo later. Also I will test next time with just uv/ir cut filter in the drawer .

Enclosed pics of settings and the last 2 EAF runs one after the other.

 

 

[Richard_]

That's odd, you were previously able to measure HFR as high as 20 but now it falls over at just over 10? The third picture of your above post shows a low HFR and doesn't follow the trend. Was the image at that point in focus (and truly a low HFR) or was the image so far out of focus that NINA incorrectly reports a low HFR? 

It'll be worth seeing what happens without the l-extreme filter and using the UV-IR filter. 

[ninjageezer]

if the star gods allow I will try tonight.....with the uv/ir filter.