ZWO EAF Worthwhile?

One of the biggest benefits of auto focus is being able to adjust focus with changing temperatures with only a minimal interruption to your imaging sequence. If you're shooting mono with a filter wheel I'd consider auto focus to almost be a 'must-have'.

I installed the ZWO EAF on each of my telescopes and I find it to be a worthwhile investment. In my case, I control everything with the ASIAIR Plus so the integration between all my ZWO products (ASI294MM Pro camera, EAF and EFW) is outstanding.

Prior to going mono, I was using my EAF with a OSC camera (ASI533MC Pro) and found that automatic refocusing was beneficial. I live out in the Arizona desert where 20F to 30F temperature drops during my imaging session is quite common. Prior to the EAF I could definitely see where I would lose focus during my sessions. 

Once I made the transition to mono imaging I found the EAF to be an essential piece of equipment. Auto refocusing after each filter change along with refocusing for temperature changes allows maximum flexibility during imaging sessions. I set up my imaging session and sleep soundly knowing that I will have good data the next morning.

I found the installation to be real easy for my Zenithstar 61. My Celestron 6SE was a challenge but only because ZWO does not have a mount for the 6SE. Once I modified an 8SE mount to fit my SCT installation was easy. The attached YouTube videos helped me.

SCT
https://www.youtube.com/watch?v=IJErn8xQxS4

Refractor
https://www.youtube.com/watch?v=j66cVp_B_Cg

It’s settled then. I’ll be adding this to my setup.

Do you still achieve initial focus with a bahtinov mask or is that out of the equation with a EAF?

I loosened the set screw on my EAF so that I could manually focus using a mask. Once that was accomplished I tightened the set screw and set the focus point (using my ASIAIR Plus) at 30,000 which is the midpoint for the EAF. This is probably not critical for a refractor but definitely necessary for the SCT since the focuser range on the scope is probably beyond what the EAF can handle.

Once I got my EAF's set, I've never needed my Bahtinov masks again. I have a set of Optolong 36MM LRGBSHO filters which are nearly parfocal so the EAF has no trouble achieving focus for me.

Jason Quitadamo:
I no longer use a Bahtinov mask. I just run the autofocus routine in ASIAIR at imaging start and on filter changes. What automation software do you plan to use?

I run everything through the asiair pro currency fly so it sounds like a no brainer right? Any suggestions for instruction on how to run the autofocus routine or is it pretty self-explanatory?

It doesn't get much easier. I keep this site bookmarked as a reference. It will explain everything you need to know. There's some other good writeups on the ASIAIR in there.

https://eastwindastro.blogspot.com/2021/04/how-to-autofocus-with-asiair.html?m=1

I’m also curious about suggested settings for shooting SHO with my zenith star 71. Anyone with a similar scope shooting SHO want to share?

I have a Zenithstar 61 which should be similar. I post all of my capture data on my image Astrobin library. I’m no expert by any means but as a general rule of thumb I do find longer exposures beneficial for narrowband. I can get away with 3 minute subs for bright targets but I will go over 10 minutes on faint objects like the squid nebula.

Once moonlight becomes an issue, I focus on SII and Ha data as Oiii is not as forgiving under heavy light pollution. I’m generally keeping my broadband imaging to not more than 3 minutes max.

Anytime I’m imaging a new target I take advantage of Astrobin’s search features to find a reference image from an experienced user with equipment similar to mine. I find that helpful to set my capture parameters and along with a reference while processing the image. I have a long way to go in my learning journey so I really try to leverage the info freely provided by the members here that actually know what they are doing. I’m not there yet!

How is your experience with the ZWO EAF?

I have been manually focusing and locking it in, never used auto focus. How vital is it / what are the really benefits?

The only benefit is if you're not there. Otherwise none.

Do I need the model with the hand controller or is the regular one fine?

I took the model with the hand controller because I was not sure but you can live without
I used it 2-3 times in several months when I did not want to turn the computer on to move the focuser, in other words, I used only during daylight, on my desk

Probably wise given the small cost difference. Where does the temp cord plug into?

The temp cord plugs into the same socket as the hand controller, so you can only use one at a time.  I went for the ZWO EAF 5V and the temp cord only and don't miss the hand controller.

FWIW:  I haven't looked back since I got the EAF; it makes life so much easier if you are doing unattended control of the scope (which I do from inside on really cold nights).  I do an automatic re-focus on filter wheel change and try to make sure that the filter wheel changes happen every hour or so to take care of temperature changes as well.