ZWO EAF help please

[Jonny_H]

Hi all,

This is quite possibly just me being daft, however I have just installed a ZWO EAF to my Esprit 100ED and whilst the weather is bad i thought i would have a play inside - setting it up etc.... The EAF will be/is controlled by my ASIAir Pro.

According to the ZWO EAF manual - it states "The 0 position is recommended to be set to the position when the focuser is fully retracted. The maximum number of steps is recommended to be set to a limit position less than or equal to the full focuser stroke".

All well and good, however when i retract my focuser and set the current position to 0, the EAF doesnt seem to like any movement at all, i.e. if i set a go-to position of say 20-30, and i press the direction button within the focuser screen of the ASIAir (under the fine setting) it goes to say 12-15, double bleeps and then stops.  I have checked the reverse option isnt selected and I am definitely pushing the correct direction arrow in ASIAir. (see below).

Now, if i set the current position to something random, like 10000, 32000 etc.... when the focuser is fully retracted - it seems to like this and will move to pretty much any parameter i set + I can move to said parameter by pushing the respective arrow within the focuser screen on the ASIAir.

So.........am i being dim and missing something in the ZWO manual?  Probably the former but i wondered if anybody can help

 

Thanks,

Jonny

Edited December 2, 2021 by Jonny_H

[Budgie1]

IIRC, when I set mine up with the ASIAir Plus I found the same thing.

I ignored the manual and set 0 when fully extended and max limit when fully retracted. Used it on two evenings so far and it works very well.

[Jonny_H]

10 minutes ago, Budgie1 said:

IIRC, when I set mine up with the ASIAir Plus I found the same thing.

I ignored the manual and set 0 when fully extended and max limit when fully retracted. Used it on two evenings so far and it works very well.

Ah ok, so in essence you did the opposite to what the manual states and that works?

Perhaps a translation issue or something within the manual? 🤔

I shall give it a go and see where I end up

[Budgie1]

3 minutes ago, Jonny_H said:

Ah ok, so in essence you did the opposite to what the manual states and that works?

Yep, I've just fired up the ASIAir to check and it extends when I tell it move to 0.

Thinking about it, it should work as described in the manual because fully retracted is a definite zero point. But for this to work you would need the reverse setting active all the time. 

Still, it works fine the way it is so that'll do for me!

[Jonny_H]

10 hours ago, Budgie1 said:

Yep, I've just fired up the ASIAir to check and it extends when I tell it move to 0.

Thinking about it, it should work as described in the manual because fully retracted is a definite zero point. But for this to work you would need the reverse setting active all the time. 

Still, it works fine the way it is so that'll do for me!

I just had another play with the EAF and you are correct. In order to achieve what the manual states, you need to set the position to zero when the focuser is fully retracted, and ensure that the reverse setting is enabled. The latter point seems to be missing from the manual.

Not sure if it really matters if reverse is enabled or not but it seems that this is needed to meet ZWO's recommendation!

[iantaylor2uk]

I must admit I've never bothered with zero setting - on my WO 81 GT IV telescope there is a ruler inscribed, so I know roughly where the focus point is - I just leave the tube in that position so I know it is roughly focussed when the camera is on. 

When the ASI Air Pro does the auto-focus function, it then doesn't have to move very far in either direction.

I think the zero function position is important if you start with the tube fully in or fully out so as to stop the motor trying to force the tube further out or further in. 

[StevieDvd]

The manual says to set 0 as fully extracted for standard saddles and for curved saddle I quote exactly "The 0 position is recommended to be set near the focus of the
focus of the focus holder".  That's why there is a reverse setting, though I don't follow why the saddle type should make a difference.

You should really set the range to limit the focuser travel to protect the stepper motor. Most times the questions about settings arise after the motor has been fitted, so to get the range value I'd suggest:

• Set the focuser to fully extended first and bring it back in a little as a tolerance setting.  Set this as zero.
• Move the focuser until almost fully retracted and note the position count.

On startup the stepper motors tend to default to zero and don't save the current setting when powered off.  Hence, I use my zero point as almost fully in and use that as my startup & switch off position. Most focuser software allows the option to set current position to zero so I find it easier to do that from a retracted position as it makes the scope easier to pack away.  If your normal 'in focus' position is nearer to fully extended you could make fully extended as your home/zero position.

I have a clutch on my moonlite focuser so can easily move the focuser without engaging the motor, but my lakeside motor is fixed. It was from following the lakeside manual that I 'assumed' the correct way to setup was with 0 almost fully in and to be fair their setup instructions were more informative and detailed. The ZWO manual is a little brief so it' s not surprising the setup questions pop up so often.

It will be interesting to see what others have as their zero point (fully in or out) and why. I'm not averse to being corrected/advised on better methods.

 

Steve

 

 

 

[Budgie1]

17 minutes ago, StevieDvd said:

On startup the stepper motors tend to default to zero and don't save the current setting when powered off. 

The ZWO EAF does retain the current position of the stepper motor when powered down. I leave my scope set up and ready to put on the mount, when I started the ASIAir Plus last night it showed the current motor position was 20820, which is about right for focus on my Evostar 80ED.

What I haven't tried yet is using it with APT and whether the position is retained by the EAF when swapping between APT & the ASIAir.

[Jonny_H]

Does the EAF not have a 'safety circuit' which prevents over travel of the focuser? E.g. it shuts down if it detects that it cannot move the focuser in or out?

Not that I am willing to try it but I thought I had read it somewhere!?

[scotty38]

I set mine up with the focusser fully in (shortest length). I then moved out a very short distance and set that as the 0 point just to make sure that when coming back in it didn't reach an end end stop etc. After use it also gets left at the focus position.