Thanks for this video, Kurt. This is the best, most followable method of learning this (that I've seen!) And congrats on all of your recent publications!
Thanks. I was actually looking into the Pegasus at the same time I purchased the EAF and was wondering if I would have been better off with the Pegasus...
One suggestion, Try testing BL with the scope on the East side then the West side. You may get a different plot due to tilt of the focus train. Sometime called fishtailing. Great video. Hopefully APT will be coming out with auto focusing soon.
Thanks, good thing to be aware of. In my case it appears to be the same on both sides as I did a few autofocus backlash tests using NINA's automatic focus when the scope was on the opposite side and the values were equivalent to this.
Yeah, it sure is. I was surprised. On the other hand Cuiv and others have experienced similar values. The backlash correction has been work great for the last four years so far. I have a newer EAF on another setup which has much less backlash. Cheers
AFAIK, the backlash can be from the gears within the EAF, the shaft / flexible bush assembly and the rack and pinion of the existing focus tube... I might have used some incorrect terms here.
@@AstroQuest1 it certainly needs to be factored-in.. But starting off out of focus is best, then making notes of the numbers as you go into and out of focus again.. But this this will be frustrating until you know your backlash value before winding back to focus again
So, I decided to measure the backlash on my EAF using this method because for some reason I couldn't get a "straight line" of stars in NINA to estimate my backlash. But it looks like my backlash is ridiculously low. When I step forward by 10 steps, I can immediately see movement when I run it back 10 steps again. And the same with 8 steps and 6 steps, and I'm pretty sure I can see movement at 5 and 4 steps too in either direction when I vary back and forth. After this I just can't distinguish any movement either way. I wonder if I just got lucky and got a good, precise model?
I initially had a BL amount around 90-100. Spent a few minutes adjusting the stock focuser itself and found there was about 75 “steps” of BL in the stock focuser. I adjusted that out (WO Z73 w 2 speed)) and my avg after that was around 20-25 steps. Hope this helps.
Using the EAF in SGP, ZWO recommend setting a backlash of between 100-200 in the out position, seems to work OK for me with a setting of 100. Still it's a lot of backlash in such a small motor. I think I will try the Pegasus Astro Focus Cube next, it has some good reviews.
Where was that recommendation? Or was that for using focus in SGP which makes sense to me now since the SGP uses a backlash overshoot method for obtaining focus - I may get into that in a later video since NINA can do that method now. I would be interested to see how Focus Cube works as well in fact I was looking into that at the same time I purchased the EAF. The Focus Cube has a higher lifting weight capacity. I am OK with the focuser now that I understand it - Obviously I wish the backlash were smaller. If I do end up getting another focuser I might look into a Moonlite or something like that - Pricey$ of course.
@@AstroQuest1 This is in the EAF manual ,on the ZWO site, page 25. They have all the settings for the various aquisition programmes. These are just the backlash settings for SGP. astronomy-imaging-camera.com/manuals/EAF_Manual_EN_V2.2.pdf
Thanks for the great video, been looking into calculating the backlash on my autofocuser for a while. One question though, what is the plate you have on top of your scope? Did that come with your rings or custom order? Thanks again.
I made it. (ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-sARzUK6yXrA.html) or (astroquest1.blogspot.com/2019/06/the-pegasus-astro-pocket-power-box-best.html)
As for my EAF I've found a backlash value of 25 before it starts moving, so I'm pretty surprised you reach 100 steps before it rotates. Maybe I'm lucky I don't know, but I still would like it to be smaller, like 5-10 max 😅. Now the question is: What would be the best "fine focusing settings" (steps) regarding the backlash you find? Should it be the backlash value itself, or a greater one? 🤔
20 steps would be the min for my setup but it might be difference for you. Cuiv the Lazy Greek just bought a second EAF which has very little backlash so maybe ZWO has better QA/QC. Good Luck
looks like the EAF is about as good as my mount motor/gearboxes for backlash. That is to say rubbish. Lucky for you backlash in a focuser is less critical. The EAF is copping some stick on the ZWO forums, hopefully something good will come of it. Their 60mm guide scope is another that could stand a revision IMHO. A decent enough scope but put one of their mini guide cams into it and you have back the camera out 30mm which does not leave much engagement just to reach focus. I'm using a unitised stepper/gearbox from Ebay directly driven from the UPB Pro v2 on both of my scopes. Works well for me. Still waiting for a confidence inspiring autofocus routine within APT. NINA's autofocus is almost enough to convince me to jump but the UI is not as easy as APT.
Yeah fortunately the EAF is not a huge investment and as long you know what it is, it is workable. I found NINA much better in than SGP and it is going to give SGP a run. I used NINA the second night for complete imaging and control including a meridian flip and had it checking focus while imaging. I still prefer the way APT does things minus the focus/autofocus. What I have been doing the last few times is setting up on a target in APT, turn on NINA for the Autofucus since it does not need a bright star like APT does when using a Bahtinove Mask, andthen start imaging with APT. If I want to check the focus or do a filter change I turn off the camera in APT and turn it on in NINA and check the focus, if it is not in focus, do the autofocus.
@@AstroQuest1 interesting both of us have a similar assessment of NINA's UI. I have been doing the APT-NINA shuffle too :) Do you know of the latest updates to NINA where the autofocus always approaches the set point from one direction? Suddenly focuser backlash is irrelevant.
