I am having a very difficult time getting my OIII filter to auto focus with the Micro Touch Auto Focus on a C11 with Hyperstar .
Trying to use the LUM filter as the main filter and then entering the offsets for OIII to focus with is cumbersome because there is no filter wheel with Hyperstar.
What I have been doing is slowly manually focusing the OIII filter as best I can in order to get it close and then letting the auto focus run a couple of times to narrow it down. However it never gets a sharp focus.unless I tweek it some more afterwards. I have tried different step sizes and still have not found one that will give me the V shape. The strange thing is that I do not seem to have this problem when I am using my ED102 with Moonlight Focuser in SGP, it’s only happening with the C11, Microtouch and Hyperstar.
My current settings have been around 150 for Coarse Step and anywhere from 5 to 30 for Fine Step.
Do any of you have any ideas or thoughts that could help me a little here? It’s depressing to work all night and find that your out of focus the next morning.
I don’t know it could be. I don’t seem to have this problem with Ha or SII but then they are a lot more contrasty and easier to see. My Bahtinov mask came in today so I am going to try there and see if I cannot get a little better focus.
Let’s not forget that it’s me doing this so there is that!!!
It worked fine for me with EdgeHD11 and autofocus with the primary focusing knob. With narrowband you probably want to aim at a star cluster and use 1-2 second exposures.
If you focus with the primary knob both for f/10 work and hyperstar then the focus curves and step sizes shouldn’t change much - because they both involve focusing by moving the primary mirror.
You may also need more exposure on that filter as well. Check the mean and Max levels of your ha and co parenting it to your O3. That should give you an idea of how to scale the exposure if that’s the issue.
I’m setting back up now for tonight and will take all this in and get back with you. I appreciate all you taking the time to assist me with this.
I started with SGP last month and have gotten a pretty comfortable workflow going but the autofocus is still just on the edge of my understanding the intricacies of all that it does.
I’m finding that time on the scope and doing it followed up by questions is far better for learning than reading all the time.
For AF we typically recommend that the high HFR be around 3-4X that of the low hfr. So if your low is 1.2 then you want to get your high somewhere around 3.6-4.8. This is not an absolute…just a good window to start with. If you’re getting less than that up the step size. If you’re getting more than that lower it (or leave it alone if focus is ok).
Thanks everyone for all of your input. I had a better experience last night with the Bahtinov mask installed. I learned that pointing it and centering it on a decent star is the way to go rather than just letting it hit full field. I got the tightest focus I have yet to achieve but I still had to manually tweek it after the autofocus ran.
I’m still not getting the V everyone likes to see but in my book focus is focus. Mine usually runs horizontally from right to left leaning down in a straight line. Typically I’ll get my star in the middle of the line at the lowest focus point. The second focus comes in above that one and crosses it with green lines somewhere usually near the star.
I guess if I had to describe it the green lines are making a V but it’s sideways. I don’t know hmmmm.
Either way my HFR for the total image of 20 minutes was 2.05 HFR as apposed to 3.87 the night before. Stars are round and look good so I guess it’s working in a strange way but working.
I was kind of thinking that once I got it close to focus that I should drop my fine step to 10 or 15 from 25 to 30.
I was reasoning that if it was too high that I would blow right past focus.
I think I might be wrong in my understanding. I’m going to look at the link you sent me right now and go through it. It takes me a little while to get an understanding of how this works when reading about it with all those numbers.
I don’t know how to post a picture of the graphs or I would do it. Do you just do an crtl print sceen and copy it?
Let me run through this to be sure I have it right.
I understand that I am supposed to get it as focused with my bahtinov mask as I can and then remove it and take a frame. In the tutorial he got .90 HFR and so you wrote that down.
It then says to start looping and move your focuser out until the HFR gets to 3 to 5 times greater than the number your wrote down which in this case was 4.89
At this point it says to do this.
Subtract the “in-focus” focuser position from the new (current) focuser position. Multiply this number by 2, divide it by the number of “Auto Focus Data Points” minus 1 and you now have a good “Step Size”.
I get that I’m supposed to take the In-Focus number and subtract it from the new position etc.
But I am unclear on what the “Auto Focus Data Points” are.
What are those? I think once I understand that I should be able to put this into practice and try it.
Oh Okay thats right! I forgot about that setting. It didn’t click in my head that that is what the instructions were referring to. Mine are set to 9.
Cool I’ll go run those numbers right now.
Thank You.
I have a few plate solving questions to get resolved to complete my ability to press “run sequence” and walk away but I figured I would take these two issues one at a time.
So I will sift through the prior postings first before I move on to that.