Auto Focusing with the ASIAIR Pro

[@aw7425]

Excellent and your helper is priceless. Clear skies

[@johnellsphoto]

Quite informative and useful! Your daughter is adorable! And, capable. I can imagine her in the years to come having her own set up! Thanks a lot for this tutorial.

[@astrokev99]

Subbed. You explain things very clearly and precisely, which is a rare gift. Well done and thank you. Your demo of backlash with the kids toy was priceless!

[@tullyfisher]

Great video. And an adorable little helper. 👍🏼😊 Clear skies

[@texasbackyardastronomyglen9040]

going to try my first EAF in a couple of hours.. so grateful to you for this video. using your tutorial i will determine backlash first .. your 5 year old assistant did a great job ! thank you both. TexAstro 🙂🔭

[@MrWilsonsChannel]

Glad to hear it! Good luck 👍

[@albertsmith5581]

Thank you. I sent to my 5 year granddaughter. See loves looking at the stars with her grandpop.

[@kirostar12]

Thank you man! You make my stars to look better again . I paid for nothing to Sequence Generator Pro for their program to use the AF settings but they don't have the backlash option and the ASI focuser didn't work there properly. Now I use the ASI software to capture my images and the AF works flawlessly with your settings even on my SCT telescope.

[@MrWilsonsChannel]

I love to hear this! So glad you got it working 😊👍

[@jerryfox3731]

well done. good information. You were very lucky to have such a capable assistant.

[@FAstroHD]

Fantastic video explaining backlash and setup. Thanks for taking the time putting this together and sharing. It has certainly helped me.

[@danno1374]

Thanks for the video! Just installed my EAF. Looking forward to trying it out!

[@MazzifLOL]

Glad you got it setup. I had no issue on my ASIAir Pro using default settings.

[@stevepaterson2]

Many thanks to you and your wonderful little assistant!

[@Oamaruastro]

As a new SCT owner I discovered this in advance of setting up the EAF on my EdgeHD. One thing to note is that according to ZWO, the automated focus routine does not need a backlash setting to work (it handles that on its own). The backlash entry only relates to manual focusing.

[@rossdillon17]

That's because the EAF always tests and then sets focus by moving in one direction only. Backlash is not a factor when doing this in auto mode.

[@MagicAstroMan]

Great explanation and you have a future engineer / astronomer in the making - good to see great parenting :)

[@mikeswift926]

What cutie 5 year old helper.....a star in the making lol

[@phcalama]

This procedure doesn't make sense to me but that very well might not mean it's in error. Here is my thinking. First my assumptions: 1) scope uses rack and pinion focusing, and 2) EAF has been properly attached. There is a third assumption that follows, With these two assumptions it seems to me that any backlash is a combination of the slop between the pinion gear and drawtube rack, as well as the slop in the EAF gearing. The third assumption I will make is that this slop is "relatively constant" throughout the range of motion of the drawtube. If these three assumptions hold then it seem to me that the procedure for determining the overall backlash needn't involve focusing on a star or anything else. The procedure I've applied is to use the controls available in the ASIAir app to rack the drawtube somewhere between it's two limits - moving in one direction only. Then reverse the direction, taking slow steps, until you "observe" (more on this below) the fine focus knob move. The difference in the step count between where you started to move in the opposite direction and where you noticed movement of the fine focus knob gives a good approximation of the backlash within an error equal to what you set as your slow step size and the accuracy of your detecting when the fine focus knob moved. For a better approximation use a smaller slow step size but doing so makes the observation of fine focus knob movement more difficult but certainly not impossible. Feedback is welcome.

[@astrophotonchaser]

very informative! Thanks! I have two EAFs, one for my refractor and one for my SCT. One is flawless…the other, not so much. Definitely a backlash issue…

[@MrGuitar50]

Great video! I'm having a lot of frustration with AA Pro getting good focus without using an EAF. The graphical values bounce all over the place and after 15 mins of messing around I end up just eyeballing it in the focus mode. My focus is "ok", sort of like your first picture but I want to get it more precise as you have demonstrated.

[@MrWilsonsChannel]

That bouncing you talk about is due to turbulance in the atmosphere. What you want to do is get the star size graph to the lowest point possible. When focusing manually, I'll make a small adjustment and verify that the graph is trending downward then I'll stop and let it settle for a bit. As it bounces around up and down I try to imagine what the average value of the ups and downs is. Then I'll make another small adjustment in the same direction to verify that it's continuing to go down. Again trying to average out the values. Eventually you'll see it start to trend back upward again and that's when you know you've passed through the focus point.

[@jimb7931]

Nice informative video. I've had the ASI Air for about a year and the ZWO EAF for about 6 months. I have an EAF on all 3 of my scopes. Makes things so much easier to get perfect focus. You'll really like it!

[@stargazersview6997]

thanks for your fokuss lessson and clear skies!

[@whenpigsflyobservatory]

Thanks for making the class so much fun Mr. Wilson! The bring your kid to work bit was brilliant! She stole the show. I’ve just completed the transition to the ZWO ecosystem with receipt of an ASIAIR Plus and ASI120MM guide camera This video is a real bright spot! Cheers!

[@MrWilsonsChannel]

Thank you for the warm regards! Clear skies 😊

[@calimark7448]

Nice. I had to grind a bit off of my mount (for EdgeHD 9.25) due to interference with the .7 reducer. Just a bit. Dremel to the rescue.

[@MrWilsonsChannel]

It seems like modification goes hand in hand with this hobby. I've made all kinds of tweaks to get things to work better together. I don't have the edge hd, but I've been eyeing one for a while. From the photos it does look like the reducer is extra super beefy.

[@calimark7448]

@@MrWilsonsChannel I really love the challenge. It helps keep me young ;-)

[@allenbaylus3378]

@@calimark7448next time you set up - would you mind sharing the settings for your EAF. Fine step Coarse step Backlash Want to try out different combinations on mine to see if I can get a better focus routine out of my EAF and c9.25.

[@calimark7448]

@@allenbaylus3378 Step size 3000, Initial steps 5, Backlash -Out- 1000. this is with the Primalucelabs Essato and Nina. The Edge took much larger steps than my Askar FRA400 but then that has the Zoo EAF. (30 step, 0 backlash) Best of luck.

[@allenbaylus3378]

@@calimark7448 OK - On ASIAIR - I am trying Fine-100 Coarse 300 no backlash right now Got a good night tonight and tomorrow to try to hone in the best settings for me - C9.25 with 0.7 Focal Reducer and ASIAIR with EAF.

[@bb108]

She is adorable. Great video!

[@jimforrest7852]

thanks for the walk thru... great explanation. I must agree rare gift.

[@Kelli.Hicks.5]

Very informative video, Mr. Wilson. I can understand your frustration. Very few things make me angrier, faster, than when my touchscreen devices fail to register my taps. 😡

[@darksky7810]

Great Video man. Going to set my backlash on My HD 11 this exact way this week.

[@MrWilsonsChannel]

Let me know how it works out for you

[@davidaylsworth8964]

Subbed … interesting content. I’ve just completed the ecosystem transition to ZWO with receipt of an ASIAIR + and ASI120MM guide camera. I got a good laugh about the 5 year old gag. She’s got camera skills with her antics during your monologue. I’m mostly a refractor guy however, there’s an 11” SCT waiting to be cleaned and recommissioned so your backlash calculation method was of specific interest to me. Cheers!

[@woody5109]

Your daughter stole the show, well done, such a ham 😂😂

[@chrisdavis8663]

Definitely learned a thing or two from this video! It made my first attempt a breeze. Thanks for setting me up for success!

[@kushanvyas7728]

Thanks, this is how I can fit my eaf,asair with my celestron 8se.

[@markwelsh9068]

Useful info. Your daughter was the 'star' of the show, however.

[@gewglesux]

Thanks for this video. I have the same units just not the time to put it all together. Thank you

[@astronut3496]

I asked a question on the ZWO site regarding backlash and the answer I got suggested the backlash only affects manual focus with the hand controller. When using the EAF the autofocus routine removes backlash automatically as it always finishes the focus routine in the same direction.

[@MrWilsonsChannel]

I'm quite certain that isn't accurate. After running every conceivable combination of tests on this thing, it appears that the backlash value you set in the ASI Air menu is being used by the controller to send extra pulses to the focus motor every time it changes direction. The autofocus routine zeroes in on the correct focus value by turning the focus knob in both directions several times. It doesn't watch the target star in real time, but rather goes to where it thinks it will be in focus takes a shot, measures the star size, moves again takes another shot measures the star size etc until it finds a value it believes will be the smallest star size. When it reverses direction, it already knows how much it wants to move for the next test, but it doesn't know how much of that movement is going to be eaten up by backlash. With the default or incorrect backlash value entered in the menu, it might think it's moving 100 steps when in reality only 80 steps worth of actual movement have been completed. This means it thinks it's in a location other than where it truly is. For telescopes with a rack and pinion focusing system, backlash is evidently less of an issue for some reason? With a telescope like the Raza or C8 with a worm gear style focusing knob, I had to include the backlash in the focus system of the telescope itself in addition to the backlash in the EAF. That's the part of the equation I was missing for so long.

[@napper1496]

@@MrWilsonsChannel I got in touch with ZWO to ask them about this and emphatically they said you are wrong. Auto focusing needs no backlash adjustments. Strange

[@allenbaylus3378]

I have had nothing but trouble with my EAF on my C9.25 SCT (with the 0.7 focal reducer). I am at a point where I feel that I can not even use the manual controller to get a good focus most of the time. Once in a while it cooperates. I am sure that it is totally a me issue - guy who had it before me did not have the issues with his EAF. When I had it out last night I did check that the motor was controlling in both directions. But the focus chart looks more like a line then a V curve (I do have a second EAF on a smaller refractor). Most of the time I get snowballs which I can not get smaller and the star sizes are close to 8-10. Most will not move regardless which direction I push the focus. I will get a 5 and then leave it on the one target. But swing to a different target and refocus and it is bad.

[@lazylazyshark]

thank you!

[@gigidelgado4198]

I am learning!

[@MrWilsonsChannel]

That's what it's all about 😊

[@vickiewilson6507]

Very informative video Thanks!

[@mrsrfm]

Well done!

[@giuseppececere9815]

Excellent video with very clear steps. 👌

[@curlingdan]

Stumbled onto your channel, you have a gift for explaining - especially the use of a kids toy explaining backlash. Brilliant ! Do you know if it's even possible to use the ZWO EAF with a standard camera lens ? I use a Sigma 150-600 lens on my DSLR, I also use the ASI120mm guide camera, ASI Air Pro and the AM5 mount. Focusing seems to be an issue for me, so just curious about the EAF.

[@MrWilsonsChannel]

I don't think it's possible out of the box, but if you have a 3D printer you could probably rig something up. Small rig makes a follow focus knob that contains a flexible strap you wrap around your lens. The strap has teeth that mate with a gear on the follow focus knob. You could probably remove the gear and 3d print an insert that would mate with it and the eaf. As the eaf moves the gear, it in turn would move the focus on the lens.

[@doccortex1203]

Thanka

[@NMukkavilli]

Thanks a very helpful video

[@TwitchFlys]

You know you can go into the focuser setting and change the focus point manually. For example when I start out at night I set the focus point to 30,000. Then I go 40,000 and 20,000 and see what direction came out better then I can get close quickly without having to use the manual button or walk out the scope. I live in an area where it gets down to -35F at night

[@MrWilsonsChannel]

That's a great point. I did see that option in there, but didn't really know what to do with it? That's a great application for it. Especially when it's freezing outside! I live in Southern California. Our definition of freezing is anything less than 72° 😉

[@BruceMallett]

I have the EAF on an old orange tube C8. One caution I've read often is that for move-the-mirror focusing one has to make the last focus adjustment such that it is pushing on the mirror. In N.I.N.A. this is accomplished through setting one of two backlash values (but not both). Perhaps in ASIAIR it is by making the backlash value either positive or negative? Also I just made my backlash value larger than it needed to be. My feeling is that the extra time it takes for the additional movement is down in the noise compared to the total time to do the autofocus.

[@MrWilsonsChannel]

It doesn't look like the asiair has an option like that? Maybe they already built it in to the af routine? I have a Celestron 8i special edition, which I think is the same ota as a c8, but I could be wrong. I haven't had any trouble with mirror flop or other mirror motion after a meridian flip, etc. but I have heard other people complain of such things. Maybe that's what makes it a "special edition"? 😉

[@naegeleh]

Thanks for the interesting video which helped me a lot. I have one question: for the RASA you always set fine steps to 10 and coarse steps to 100? Or are there situations to change these values? Clear Skies Herbert

[@MrWilsonsChannel]

It seems like using values that are too large will cause the unit to pass through the focus point, possibly repeatedly, which could cause you to fail to achieve focus. If you're running into that issue, try lowering the step size so the focus routine can creep up on the correct value instead of overshooting it. It helps if you start roughly focused to begin with.

[@clearskiesastro1028]

Well made video but some of the information provided is incorrect. Yes you are showing how one can calculate backlash on an SCT which is all good. The issue is that Asiair/EAF Auto-Focus does not take into account the backlash value at all when its doing its AF routine. The Fine/Coarse/backlash are ONLY used for manual focus. When the AF routine is being used, it only adjusts in one direction during each step calculation of the V-curve, it never backs up to take backlash into account. If it didin't find the V curve in initial routine, only then will it "back up" a good ways (way more than the backlash value) and once again go only in one direction from this new start point during that 2nd V-curve routine. You can ask ZWO directly yourself if you don't believe me but they've explained this several times on FB and their boards. The only value which matters in auto-focus is the AF step size and exposure time, that's it.

[@MrWilsonsChannel]

I haven't seen that documentation myself, but I'll take your word for it. I suppose it's possible to achieve the same result by passing significantly through the focus point, reversing direction, and then utilize the step size to move incrementally in the opposite direction until you hit the smallest star size. But that doesn't explain why adjusting the backlash value to the proper setting fixed my problem. I tinkered with this for months and it never worked until I figured out how to properly calculate the backlash value for my SCT. Making adjustments to the step size alone had no effect. I wonder if an update along the way modified their original autofocus algorithm?

[@napper1496]

Yes!!! Clear skies Astro I was told exactly the same thing from ZWO. only MANUAL needs backlash adjustments and changing settings for auto isn’t a good idea

[@michaelharrington7797]

Nice video 👍 just wondering once automatic focus setup has run will the automatic focuser automatically adjust focus without touching anything? For example if you change filters ext. people have mentioned presets to me but I don’t understand this as I’ve never used ASIAIr before 🤷‍♂️. I will be shooting in monochrome so really just want to know how to set up my imaging plan so EAF adjust after each filter change.

[@MrWilsonsChannel]

I don't have a monochrome camera or filter wheel, so I can't speak from experience. However, I do see options in the menu for it to automatically refocus after a filter change. So I'm assuming that is something it can do by itself. It also has options to automatically recalculate focus at set time intervals and, if you have the thermometer attachment, to automatically readjust as the temperature changes x degrees. It'll even readjust after a meridian flip. I have used the time interval, meridian flip, and temperature Auto adjustment settings successfully

[@arthurfernandez7878]

Very helpful video, thank you! One thing I noticed with the hand controller is that it does not change the encoder output (the numerical position of the EAF motor as shown on the interface) in the ASI Air as I reach a close approximation of focus, so indeed it is really useful for rough focusing, but not for the backlash counting step that you described. I presume this is normal?

[@MrWilsonsChannel]

That's my impression as well. Information appears to be one way. It is important to note, however, that the focus motor appears to have its own memory and can remember where it's at and what it's limits are, Even if it's removed from the ASI air pro. In the ASI interface I can tell it I want a range of, say 30,000. When it hits that limit, it beeps and won't go any further unless I reset it in the interface. When I remove the focus motor from the ASI all together and use just the hand controller for things like star parties, the hand controller will still max out when I hit the limit. The only problem there is I can't reset the range because it's not attached to the ASI Air pro. So before going out with hand control only, make sure you're at least roughly focused so you don't hit your limits. This is mainly an issue for me when I last used my camera and am now switching to an eyepiece for a star party, since there is a big focus difference between those two. When it comes to finding the correct backlash value, you start with the hand controller to get you roughly there. As you mentioned, the hand controller does not send information back to the ASI air pro. Thus as you make adjustments on the hand controller, the values do not change in the ASI's interface. So once you get it roughly dialed in with the hand controller, you need to switch to the ASI air's interface and use those little arrow buttons to dial it in and find your backlash. For my work flow, I usually use the hand controller first thing to get a rough focus, then I remove it and plug in my temperature probe which uses the same port as the controller. From then on, I rely on the ASI's auto focusing routines to keep everything in check.

[@arthurfernandez7878]

@@MrWilsonsChannel Thank you for your thoughtful reply! I’m relieved that this does not appear to be a problem with either the hand controller or the EAF, one can hope that ZWO can come up with an update to better synchronize these two devices!

[@abdulrahmanhareth4806]

Great video, thank you!! I have question regarding mono camera I am going to use LRGB filters, backlash will be same value for all or should I do this procedure for each filter? And also backlash should be measured every time I want to photograph?

[@MrWilsonsChannel]

Since the focus motor and filter wheel are separate devices, they will operate independently of one another. So you won't need to readjust the backlash value between filters. You most likely will need to refocus each time the filter changes. There is an option for that in the ASI Air pro focus settings menu. In fact, once I set my backlash, I've never needed to readjust it again. Backlash does very from telescope to telescope however. If you move this focus motor to a different scope, you'll have to adjust backlash again for that scope. I have two telescopes and didn't want to keep adjusting that value, so I simply bought a second focus motor. I leave both permanently attached to their respective telescopes and never have to worry about it.

[@abdulrahmanhareth4806]

Awesome! Thank you very much for the feedback!

[@subodhshettyy]

Star of the show is the 5 year old who’s definitely smarter than me 😂 Very informative video - how much of this process to calculate the backlash would change in refractors I wonder or is it the same process and same set of number in the focus panel to begin with.

[@MrWilsonsChannel]

I imagine that the process would be pretty much the same. Obviously the EAF itself would be mounted to the telescope differently. But the process of finding what backlash value to use should be the same.

[@KopLamp]

Nice video. I do think you could make a change to your step size in the autofocus settings. You only show the step sizes for the manual control of the focus in the video. By increasing the autofocus step size you get a much clearer V-curve and - at least it feels to me like that - a much more accurate focus position. On my EdgeHD 8" I use a stepsize of 60. The default is 10 I believe, and that will give you an almost flat V-curve as you show in your video. The thing with the orange plate I noticed too. On my channel I have a video called EAF or WTF :P which shows that pain point in full detail.

[@MrWilsonsChannel]

These are excellent suggestions. I might try experimenting a little more with the af step size just to see if I can get it a little crispier. Every little bit helps 👍

[@jimcollins1922]

@@MrWilsonsChannel I watched the video and noted how you determined backlash. I just got my EAF for focusing a RedCat51 and I think you method will be quite helpful for that. I fail to see how a larger step size will improve your backlash determination. I suppose it might help in general focusing, but I am a bit skeptical on that. It would be interesting to see your results.

[@MrWilsonsChannel]

I've had a few people comment on step size. Many say increasing that value will help, but like you, the more I think about it the more it seems the opposite would be true. It seems like a smaller step size would help you sneak up on the right value whereas a larger step size might overshoot the proper focus point. I suppose if you were starting from a position that was quite out of focus to begin with, a larger step size would help you get in the neighborhood sooner. However in this video you see I always manually focus to get myself pretty close to begin with. Then I use the auto focus routine to precisely dial it in.

[@MrGp3po]

I just got my EAF running on an AT115 refractor and it worked great the first night when my focus was at about 45mm on my draw tube (mid range), but the second night I put the proper spacing for backfocus on my reducer/flattener and the focus is at about 6 to 9mm on the draw tube (barely out) and what a mess. The AutoFocus routine would not focus. It was as if the large step size went the wrong way. Finally, I had to break out the Bhatinov mask and determine focus, then set that as the start point for the EAF (about 392). I tried a step size of 100, 120, 150, but 90 was the value that worked perfect. The ASIAir kept saying "increase step size" for failed focus, but lower actually worked great.

[@MrWilsonsChannel]

This has been my experience as well. It seems like using a larger step size causes the unit to pass through the focus point. When it notices it's wrong, it reverses only to shoot through the focus point again. It seems like a lower step size and starting in rough focus to begin with allows the system to sneak up on the right value without overshooting

[@Astropaesan]

Very helpful video as I am about to place my ZWO order. Can I ask, why you purchased the ASIAIRPro, instead of the ASIAIRPlus? If you had it to do again, would you order the Plus?

[@MrWilsonsChannel]

The plus hadn't been released at the time I purchased the pro. The Wi-Fi range on the pro is quite limited. The plus is supposed to have an external antenna which is supposed to increase the range. That would be a nice thing to have. I added a small Wi-Fi router to my ASI airpro to extend its Wi-Fi range in that works well. But it is another device I have to hook up which is kind of annoying

[@Astropaesan]

I appreciate your videos, and your reply. I just finished building a roll off roof observatory, with a 12” pier, on 3800lb of concrete, supporting an Edge HD, so with ZWO gear, and that EAF auto focuser we should be Rockin! Keep up the great work, my friend!

[@MrWilsonsChannel]

That sounds amazing! I'd love to have an observatory. I'm tired of sitting up my rig every time I want to use it. I just don't have the space and my skies are becoming increasingly more light polluted. Thank goodness for narrowband or I'd be out of luck altogether! Good luck with the new setup 😍

[@Astropaesan]

@@MrWilsonsChannel My spinal damage made it imperative. Set up and tear down was killing me! So I figured a roll off roof made sense as my skies are Bortle 4, anyway. Basically I did it all myself, bit by bit. Made it look like an 8’6”X 10’6” garden shed to make my wife happy. Had a friend in my Astro society machine me a pier for my scope during COVID. The plate was machines from a chunk of aluminum I found on my property. (He owned the exact same mt, so there was no guesswork re the mt plate). Just finishing hydro to the mt, and ordering some ZWO candy to make things easier. It’s basically just a shed, with a roof on rails with wheels with grease fittings, and a really big hole for all the rebar and a big foot plastic concrete form, that took about 3700 pounds of concrete. I fill the pier with beach sand, to dampen any vibrations. She is ROCK SOLID STEADY! I’m so pumped to get imaging. My first video will be the build, as it’s easier than most people think. Oh, btw, peppermint keeps squirrels, away. Don’t laugh! That has been my only real problem. Need to make the trim pieces tight to the rails so rodents cannot get inside the roof.

[@MrWilsonsChannel]

That sounds awesome! That's a lot of concrete. I guess I don't have to ask how your back got messed up 😉 all joking aside, I think you're really going to like that setup. It would be magical to just go rolling up, slide off the roof, flip your power switch, and start imaging. Clear skies!

[@Dudleydogg]

After mounting the EAF did you manually focus and find the center point then tighen grub screws? trying to work that part out before the skies clear up here

[@MrWilsonsChannel]

You can do it that way. If you are starting off way out of focus, then focusing the knob by hand will be faster than having the motor do it. If you're starting off close to focus already, then you can go ahead and tighten it down and let the motor do it. Either way, I always manually focus using the focusing arrows in the tablet interface (or use the focus controller if you have one) to get me roughly dialed in. The auto focus routine has a much higher success rate if you start off from a point that's close to proper focus already.

[@TheLonewolf75074]

Did you have to change any settings in the Asiair to properly focus?

[@MrWilsonsChannel]

Yes, this video walks you through the steps in adjusting your backlash value in asiair

[@TheFranqd]

Hi, it's very clear explanation, thanks a lots, this kind of videos are gold for beginners... but i have a question i'am sorry... I've recieved a C8 xlt this week and i'am trying to setup the EAF in Asiair pro... the point is that trying to move the focuser by hand without the EAF in C8 i've counted 45 laps turns... ( imaybe is not the correct word )... and using the EAF 60.000 steps are only10 turns ... i think a missing something... i would like to go from 0 to 60.000 steps in ASI air pro and in the C8 was translated into the entire travel of the focuser... sorry about my english... thanks

[@MrWilsonsChannel]

I'm not entirely sure I understand your question, but I'll do my best to explain what I think you're asking about. I also have a C8 and can confirm the difference in focus from an eyepiece to a camera is significant. So if your telescope was set up for eye piece viewing and now you've attached a camera and autofocuser, there will be a significant amount of focus knob turning before the camera is in focus. Each "step" on the autofocuser is an extremely small amount of movement. This is what allows the autofocuser to dial in such precise focusing compared to if we try to focus it by hand. So it sounds like you're saying 60,000 autofocus steps equates to only 10 turns of the focusing knob. I haven't bothered counting that myself, but it sounds about right. I did observe once that the difference between eyepiece viewing and camera focus was more than the maximum range of the EAF. As a result, I had to reset the EAF range in the ASI air app to coax it into moving more. In the EAF menu in the ASI Air app, there is an option for position. You can reset current to 30,000. That will let you move 30,000 steps in either direction. When you max it out, simply reset the current value back to 30,000 again and that will let you move an additional 30,000 in either direction. I discovered that this limit exists even if the ASI air isn't attached and you're using a hand controller solo. When I last used the telescope, it was focused for a camera. Well I took the telescope to a star party and didn't bother bringing the ASI air since I was going to be doing optical viewing and opted for the hand controller instead. Since there's such a difference between camera and optical viewing I had to hold down the button on the hand controller for a long time. Eventually the focus motor hit that max value and stopped turning Even though the ASI wasn't attached. There's no way to reset the current value unless it's attached to the ASI Air pro, so I had to unscrew it in the field so I could turn the knob by hand. I won't make that mistake again.

[@TheFranqd]

@@MrWilsonsChannel Excellent, thank you very much for your reply and thanks for doing it so quickly.... I used to have an EvoStar 72ED and with 18,000 EAF steps I covered the entire focuser travel. With the new C8 I found that with 60,000 EAF steps it only covered 10 of the 45 turns of the focuser .... seemed strange to me and I thought I was missing something. What I've done is what you said... I only do photography at the moment I don't do visual, knowing by hand where I do focus, I program in the EAF so that point is the 30,000 step. So the EAF is centered on the point where I focus and has 5 turns back and forth to approach the best possible focus. In the case that someday I change the focus point, due to the change of the optical train, I will have to do the same to reposition the central point of the 30,000 steps. Thank you very much !!! Fran

[@MrWilsonsChannel]

The reason for the difference between your refractor and your cassegrain comes down to the type of focusing system they both use. Most reflectors use a rack and pinion type of focuser whereas the cassegrain uses a Crayford type focuser. The gear ratios on both are very different. A rack and pinion design will move the eyepiece a distance equal to the circumference of the focus knob gear. The crayford design is going to use a worm gear which will require much more input to move the same distance.

[@fernandolonde3472]

Great Tutorial, I follow your tutorial and got to work, but I have an issue when using the auto focus to get the v curve, it start with the stars size 2.5 (more or less), it will always increase the star value to 8 no matter what I do, Have you noticed this issue before?

[@MrWilsonsChannel]

I never really took note of what size in particular it gets up too, although that might be a little dependant on the magnitude of the star it's looking at, the specifications of your camera sensor, and the focal length of your telescope? But I can say that it will pass through the focus and continue in the wrong direction for a while before turning around. It will do the same in the opposite direction as well. I suspect it's doing this to account for turbulence in the atmosphere. Stars "twinkle" due to this turbulence which causes the star size to jump around, potentially quite a bit depending on the condition of the atmosphere at the time you're shooting. So it probably passes well beyond the focus point to ensure that it's actually out of focus and not just atmospheric dispersion. I don't much mind what it does in the interim as long as it gets to the proper focus point in the end 😉 if yours is not ever getting to the proper focus, which is what mine was doing originally, then try starting off pretty close to focus and make sure you've accounted for the proper backlash. You can also try decreasing your step size. I've noticed if the step size value is too large, it will pass through the focus point on each pass and never be able to find the sweet spot.

[@fernandolonde3472]

​@@MrWilsonsChannel, I will try tonight and see the step size, bur every time I have to manually focus but when running the eaf, after while the stars looks like donuts, I really appreciate your help, Thanks

[@AstroPhotoFacts]

Great video ! Thanks for the info :) , can you tell the steps size you use on the focuser on auto focus settings ? Same say 30 steps another says 50 or 80 etc etc and make confusion , I have the C8HD with hyperstar so is almost the same telescope type

[@MrWilsonsChannel]

On my scope I use 10 for the slow step size and 100 for the fast. I get it roughly in focus manually and then run an AF routine. If you were way out of focus to start, a step of 10 would take a long time to finish, but since you're already starting so close, it doesn't take too long to dial it in.

[@AstroPhotoFacts]

@@MrWilsonsChannel I’m talking about the autofocus automatic steps , this configuration are in autofocus settings were you can change the focus to start if temperature drop or if you meridianflip or if change filters etc, the 10 and 100 steps are for manual focus configuration only ,I think :/

[@MrWilsonsChannel]

Of course. I'm sorry I misunderstood the question. Off the top of my head I can't remember what settings I use for that. I'll try to remember to plug it in tonight and check for you 👍

[@AstroPhotoFacts]

@@MrWilsonsChannel great ! I just waiting for clear sky’s to check all my 3 Zwo focuser are off of backlash, thanks to your video , I have 1 Zwo focuser in my redcat51 and on my C8HD I have 2 ZWO focuser 1 for the hyperstar connect on the C8 and another on STARLIGHT focuser to use F7 (with the reducer )or f10 to prevent mirror flop/image shift , that’s wy it’s important to know the correct steps , no clear sky’s from my side to test and when I have it’s better not lose time with testes :) , if you can help was fantastic, thanks and clear sky’s

[@MrWilsonsChannel]

It looks like I'm using an auto focus step size of 30. I would imagine going lower might make the focus more precise, but would also probably take longer to complete. Going higher might make the focus less precise. Although I haven't tested that theory. Good luck! 👍

[@Dudleydogg]

I may have missed but did you set your AF Step size under Auto Focus Settings?

[@MrWilsonsChannel]

It wasn't specifically mentioned in this video, but I use a value of 30 for that setting. I've had others tell me I should increase that value, but I find a higher number causes the autofocus to overshoot the proper value in both directions numerous times. Using a smaller number seems to allow it to sneak up on the proper value more easily. As long as I'm starting roughly in focus in the first place, it doesn't seem to take too long for it to find the focus point.

[@taco845]

W teacher

[@bbllaakkeeee]

Assuming that I also have an sct/hyperstar “rasa” even though you have an 8” and mine is a 9.25”, would the backlash be the same?

[@MrWilsonsChannel]

My value might be a good starting place, but discrepancies in the manufacturing process might make each telescope different, probably even more so across different models or manufacturers. During my research I came across several instances where many users with the same telescope that I had didn't need to adjust the backlash at all. The focuser worked perfectly right out of the box. As a result, I had a lot of trouble finding any information about how to tune it at all. It seemed like all the articles and videos were about refractors and they didn't quite apply to an SCT. That's why I was so excited to make this video once I figured out how to get it working. I figured there were plenty of other people in the same boat I was in who were having trouble finding information on how to tune this properly as well

[@bbllaakkeeee]

@@MrWilsonsChannel so out of the box, what was the issue you were having before you began adjusting the backlash? Considering the winter is on its way and with it significant temperature fluctuations, I want to be sure I have this thing squared away before I have it out on a winter night.

[@MrWilsonsChannel]

The problem I was having is that the backlash value was set too high on mine out of the box. As a result, it would adjust past the focus point with each iteration of the autofocus routine. Ths it kept passing the focus point when it thought it was just taking up the backlash and it could never find where the focus point was. After about 10 minutes or so it would time out and give up, having never achieved focus.

[@bbllaakkeeee]

@@MrWilsonsChannel I gotcha. Well I copied your settings and my focal point is showing in the 31000 range but the Star size is like 3.45, which I think is a little big, no?

[@MrWilsonsChannel]

The star size will vary with the focal length of the telescope and the other parts in your optical train. The goal is to get the star size as small as possible, which depending on the star, might still be a bit on the big side. When the autofocus routine is running it measures the star size, then it adjusts the focus knob and measures again. If the star size is bigger, it turns the focus knob in the opposite direction to take up the backlash and then a little more to make a change. The star size should be smaller now. It adjusts the knob in the same direction again to see if the star size is smaller still. It continues doing this, but eventually the star size will start to increase as we pass the focus point and move out of focus again. The focus routine may pass through the focus point several times as it zeroes in on where the bottom of the curve should be. If you are starting with your rig exceptionally out of focus, then AF routine might not initially be able to recognize stars at all. If it can't tell if the stars are getting bigger or smaller, then it won't work. For this reason, I usually manually adjust to a point that's at least roughly in focus and start from there to let the computer dial it in with an extra degree of precision that I can't seem to muster manually

[@gewglesux]

Little assistant! Hahaha

[@johnvgladden6594]

Why didn't you consider an iPad?

[@MrWilsonsChannel]

I know Apple devices are very popular, and I do have an ipad around here somewhere, but they just aren't for me. My degree is in computer science and I like to tinker with my equipment and find apple devices are too "locked down". I want full access to all the settings, including those that could break things 😉. Apple makes developing on their platforms unnecessarily difficult as well. Android development tools are free, easy to use, and support a wide variety of programming languages. I can also build non-apple devices for far less money and with better specs than Apple charges for their devices. I believe the asi air app is the same on both android and apple, however, so it really shouldn't make a difference in the final images.

[@farpadana]

iam using IOS and it doesnt shoe the star size as it done in android:(

[@kriptyc0106]

ASIAIR is a good example of a product which is designed to (1) sell you something you don't need under the guises that it makes it easier, (2) actually makes thing harder, and (3) limits your choices. Learn a little bit about KStars and you'll discover what autofocusing is supposed to be like. No manual 1/2 way focus needed, no building your curve 'manually' just setup, press focus and let it figure out focus. Good luck with all that but when you hit the third and fourth problem with that thing, I think its time to consider something else. ;)

[@MrWilsonsChannel]

I started with a laptop but rapidly decided it wasn't for me. I want to keep my rig as portable and power independent as possible. I've seen some people using a raspberry pi to create their own "home brew" asi air and that's actually a pretty cool solution because then you can use most of the laptop software options on linux and remote in on your tablet to control it all. But that's a lot of effort. One of the things I like about the asi air is it's virtually as plug and play as you can get. Yes, there aren't as many options as with the laptop, but if it gets you comparable results with less effort... There's nothing wrong with that. The problem I describe here was 100% my fault. I wasn't using it right and I couldn't find any documentation to help me. Once I finally figured out what I was doing wrong, it started working great. Hopefully this video will help others who are experiencing similar issues. As long as you manually adjust the stars enough for the computer to recognize them as stars, you hit the button and it does it's thing. It's super easy, lightweight, and really cleans up the cable management. But it certainly isn't without its drawbacks. It locks you into the ZWO ecosystem. I already had all their gear anyway because I think it's all pretty top-notch. But if you wanted to use other kinds of cameras and accessories, it certainly wouldn't be the option for you.

[@astrokev99]

@@MrWilsonsChannel nicely answered 👍👏

[@dgv646]

Great focus! ... awful process, god awful

[@monteroder2708]

What were you using as a step size?

[@MrWilsonsChannel]

At 5:41 you can see I'm using a fine value of 10 and coarse of 100.

[@monteroder2708]

@@MrWilsonsChannel I wasnt asking about the coarse and fine as they have no effect when running the auto focus. I was referring to the step size setting that would affect the curve.

[@monteroder2708]

These i believe are in your auto focus settings