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I thought I remember a post from someone that indicated not to use Autolock when imaging? Can anyone confirm whether that is true? I am tracking and live stacking in sharp cap and just wondering if Autolock is a factor or not…

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Mike

Hi Mike,?

That was me. Here's the issue. When you do an alignment any errors caused by the user, not having the object perfectly centered for example plus mount errors, non-orthogonality in one or more planes, things like that WILL cause the 'model' to be incorrect. So although the ServoCAT will do a GOTO to where it is told to go and it will track according to the data provided to it - the path that is followed is not going to be necessarily accurate over time.?

What AutoLOCK does is it a) allows the user to set a new reference center point - say you're looking at M13... and the Argo knows this (it afterall is the only part of the system that 'knows' this)... and you do a GOTO. The object is slightly off center even though the GUIDE values read 0.00, 0.00 (or very close to that)... you center it using the HC. This HC action will tell the system to "reset" the center point FOR this object at that location in the sky as provided by the encoders on the telescope.?

If AutoLOCK is on any 'error' values that the AN sees in GUIDE values will be, through a closed loop correction system between the ServoCAT and the Argo Navis, driven to 0. So the AN will show GUIDE values that stay the same (remember that the encoders are incremental and thus there is always a non-actual drift or apparent drift in the numbers caused by the fact that the encoders are incremental). So if for example you recenter the object and the GUIDE values show 0.03> and 0.01^? .... these numbers will stay the same as it corrects to this position.?

That actually works extremely well - I dare say perfectly. As I've stated from the get-go?:?tracking ALL-NIGHT-LONG with zero accumulated error. This is true.?

But now we're back to the 'model' issue. The fact of the matter is is because of unresolved errors (mount, user) the object will still drift over time - but the drift will be much less. [also because of field rotation the object might rotate to a different place in the eyepiece view]

So - in theory this will help for imaging as well. And it does. But for the reason described above its not an be all to end all.?

I have been playing with adding a guide scope and using the ST4 system to control the scope for gross errors. I did this to cancel larger errors causing imaging to lose the ability to go longer because the object is pushed to one side... this is ongoing. This, I don't believe, will be compatible with AutoLOCK because I honestly don't remember considering it when designing and implementing AutoLOCK. So I don't think the inputs from the ST4 're-center' (and thus start from 0 reference) the object location. If not it will always be driven back to where it was 'locked' to begin with.?

Hope that helps.?

Gary?

Thanks Gary I think I understand now and appreciate the explanation. I am very interested in following your ST4 attempts. Please keep us updated once you have a process and settings that seem to work for that.

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Mike