ASI Air Plus and EAF

[AdamJL]

Hi all

Recently picked up an ASI Air for a mobile rig. What a fantastic little unit this is!

Anyway, is there an obvious way of calibrating the EAF?

By default, it looks as if the max step limit is 60,000.
Is it just a case of extending the focuser until it stops moving, then marking that position as the maximum step limit?

There's no calibration routine built in that I can see unless I'm missing something, but my guess above seems to be one way to do it, is there another?

Cheers

[RyanJones]

Hi Adam,

If you go into the EAF section in the AIR you can manually move your focuser all the way to its limit then there is a box that looks like a box with a pencil. Push that and you can tell it that that position is 60,000. Alternatively you can rack the focuser all the way in and tell the AIR that that position is 0. That would probably be my preference. Hope that helps

[AdamJL]

Hi Ryan

I'm on the right track then, thanks.

I'd set the 0 point with the focuser all the way in, then went out until it couldn't go any further. That turned out be about 19,500.

Went back to the zero point, and set the Max Step Limit to 19,000.

So I should be able to focus anywhere in between those points.

Cheers!
Adam

[Zuts]

Unfortunately that doesn't work for me. For example, on my c9.25 edge going from one end of focus to the other requires resetting the EAF to zero around 10 times, i.e. it is around 600,000 steps.

The only way to focus I find is to know where rough focus is and manually set the focus to this point. I can then go back 30,000 steps and set this as zero. If i don't move the focuser for visual then this is fine. If I do I have to manually reset to the rough focus point again.

By manually I mean loosen the grub screw on the EAF and manually turn the focuser.

Your scheme works, but I think only because the ratio of focuser knob turns to focus travel between fully out and fully in is not so high.

I am not sure why ZWO set this 60,000 limit, maybe they should have used a 64 bit integer as the step counter :)

[RyanJones]

Hi Zuts

I get what you’re saying. Surely though you could pick an intra focus point far enough away from your focal point and call that zero then your focal points will always fall in the 60,000 step range ?

[Hemi]

Hi Ryan,

The focus range between visual + reducer to camera at f10, is way bigger than the max 60000 steps of the eaf. I never could achieve all scenarios without having to reset the count to zero.

I swapped the eaf to my frac and got a celestron electronic focuser for the sct which can use the entire range.

…sorry Adam.

[RyanJones]

Ah I see. That makes sense. I wasn’t considering all scenarios. I have a C9.25 too that at some point I want to setup for AP but my plan was to use an external focuser to avoid mirror flop.

[AdamJL]

ha, no worries, and no need to apologise. It's good for others who stumble across this thread in the future.