12 replies to this topic

[johngwheeler]

I’ve just installed a Rigel Sys nStep focusser to my single-speed Takahashi focusser, but am having difficulty getting it to work. I’m aiming to use it with Sequence Generator Pro, and have successfully connected to the focusser, but have yet to get it to actually focus, either automatically or manually.

 

The various ASCOM-compliant driver settings screen are not  the easiest to understand, and quite a lot of the buttons seem to have very little effect.

 

The main problem iis that I can’t get it to coarse focus at anything like a reasonably speed. The motor seems to be ticking over very, very slowly, but I only see one jump in the gears every 30 secods or so. There are lots of options in both SGP and two 2 driver control panels, but it’s not obvious what reasonable values should be. I’d like to have fine control over the focus, but also the ability to move the focus tube at least 1mm/second when rough focussing, preferably faster.

 

Can anyone share their settings with me? This would be really helpful!

 

BTW, I know the controller box has a potentiometer to change the rate, but I assume this is for manual use, and that the ASCOM drivers override this. Or maybe not!

 

Thanks for any guidance.

 

John

[rgsalinger]

You control the speed in the Rigel GUI. There is a slider, I don't have system in front of me right now, on the left side of the GUI that says something milliseconds per step. You move that all the way to the left and the focuser speeds up. Memory says that there are only two candidate sliders so try one and then the other. AFAIK there is no disadvantage to setting this as high as you can. One of my focusers stalls at max speed so it is set down just a bit. I think that you will always find automatic focus to be slower than you might wish it to be. That's why it's important to start every night in a "near focus" condition. Racking the focuser in all the way and then out with the motor is going to be tedious.

Rgrds-Ross 

[rkayakr]

In addition to speed issues I find that auto focus software has a very difficult time if you don't start close to focus. If I'm not close, I unlock the focus motor and adjust by hand until focused by eye, then lock the focus motor again.

[johngwheeler]

Thanks for the suggestions. I think I may have the ms/step set way too high (250ms) as I thinks it’s labelled “max ms/step” (or similar), so I assumed this would not be fixed. I’ll try a value of 10ms/step, which should speed things up.

 

It’s a lot more complex than I expected with all the option in the two ASCOM screens and the SGP controls.

 

I also had a problem with SGP failing to run autofocus bacause if complained that it had “insufficient travel to move in 30 steps”. The focusser tube was into the middle of its range, so I guess it thought it was at the end of range. What techniques do you use for “zeroing” the focusser? Find a point in the middle and then go +/- of this point, or rack in the focusser manually all the way, and set this to zero?

[Stephanh]

I also had a problem with SGP failing to run autofocus bacause if complained that it had “insufficient travel to move in 30 steps”. The focusser tube was into the middle of its range, so I guess it thought it was at the end of range. What techniques do you use for “zeroing” the focusser? Find a point in the middle and then go +/- of this point, or rack in the focusser manually all the way, and set this to zero?

I had the exact same problem the first time I used the Rigel system with SGP.   SGP does not allow negative values for focuser position even tough the focuser was in the middle of its available run.  I had done a manual focus with a Bahtinov mask and engaged the motor there.

The second time around I initially focused with the Bahtinov mask again but using the Rigel GUI to do so.  It took a couple extra minutes but it satisfied SGP.  Auto focus ran without a problem for the rest of the night.

[johngwheeler]

I had the exact same problem the first time I used the Rigel system with SGP.   SGP does not allow negative values for focuser position even tough the focuser was in the middle of its available run.  I had done a manual focus with a Bahtinov mask and engaged the motor there.
The second time around I initially focused with the Bahtinov mask again but using the Rigel GUI to do so.  It took a couple extra minutes but it satisfied SGP.  Auto focus ran without a problem for the rest of the night.

Thanks for sharing this. So it sounds like the ASCOM reported position needs to be reset to zero to allow SGP to work (to prevent negative position numbers).

What step sizes, times etc. do you have in your configuration?

[rgsalinger]

The step size is determined by the native focuser, not the Rigel system. To measure it, manually rack the focuser all the way in. Then move it, using the nStep, 10000 ticks. Now measure with a ruler how far it has moved. Divide by 10000 and you've got your answer. And, yes you need to make sure that you aren't trying to go below zero when moving the focuser. The GUI provides a way to set the highest possible number. I just set mine to 100k and don't bother with refining it.

Rgrds-Ross

[Argyll1986]

Hiya John,

Hope you are now getting your rig focussing well.

For sure, the devil is in the details .... keep at it ...     For me that has mostly been in finding the correct settings ... mostly, that is.

After working through all the settings, during the original setup and over several attempts, I continued to have chronic and nagging issues that showed up within the autofocus routine in SGP.

What I eventually traced that to was me failing to ensure that the two gears on the Rigel focusser setup were snug together.   I had some looseness, some play in the gear meshing -- and that was causing havoc with the SGP  autofocus routine.  As soon as I tightened up the mesh on those gears to remove the play, things improved wonderfully. Now, I love to watch SGP run autofocus .... really, it is such a rush....

 

By the way, yesterday, I installed a third Rigel nStep focusser on my gear. (Two refractors and now on an SCT).

Am very happy with these focussers .... or else I wouldn't have three of them!

The cool thing is is that if you want to have more than one, you only need to purchase the stepper motor and bracket - because you already have all the other stuff, from the first installation (the USB hub, temp sensor, etc).

With luck, over the next few days, I'll field test the SCT with its new Rigel.

 

Anyhow, hope this helps a bit...

Best

Jeff

[rigelsys]

I've been collecting SGP screen shots from  users -- its a  pretty good way to show all the settings, so any other contributors, just send your rig description and what the screen snapshots, like the following for an AT65.

 

 

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[kolsen]

Another bit of information about SGP auto focus setup is to look at focuser backlash.  I had to set a backlash because after a successful auto focus V curve SGP had a hard time moving the focuser back to the position it determined the best.  In the focus control panel select the Other button, then set your backlash.  I set mine to IN and a compensation of 30(I think).  This was with a 2-inch Feathertouch focuser.

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Edited by kolsen, 18 April 2018 - 10:25 AM.

[johngwheeler]

Many thanks for all your input to my question!

Some very useful screenshots for me to compare with my settings.


John

[Star Slinger]

Using an ASI1600 and an ES ED80 with the Rigel Nstep.......does anyone maybe have a screenshot of those settings? Meh, worth a shot asking lol.

[rigelsys]

Using an ASI1600 and an ES ED80 with the Rigel Nstep.......does anyone maybe have a screenshot of those settings? Meh, worth a shot asking lol.

you might also check SGP user group also.