AutoFocus C14/Feathertouch/MicroTouch

Currently using SGP

Using a C14, with a .63 focal reducer, and a Canon T3i.
The factory focuser was changed out for a Feathertouch, and on that, i’m using a Microtouch focus system.
Autoguiding is done on a separate guidescope/camera.
I am taking 3 to 5 second exposures (for focusing) at ISO 6400, which is sufficient for most parts of the sky as far as finding stars. with this focal length, sometimes longer exposures are necessary.

I am NOT using SmartFocus, as this scope has a central obstruction.
I’ve spoken to Starizona, and using the Microtouch/Feathertouch combo, they suggest NO backlash compensation.

I am having a hell of a time getting autofocus to work properly.

I have tried changing the values for minimum star size, steps, and data points.

The closest ive come to this working sporadically is
Steps 80
data points 9
minimum star size 4

I’ve had limited success. The thing that really makes me wonder is, Sometimes I will get a good curve, with the green line, and a 98-100% quality, then it will rack the focuser to a different position, get a worse reading, and fail.
I guess the part that I’m not understanding is, if it successfully finds a good position, why in the heck would it keep trying other positions and then fail?

Does anyone here have the same or similar setup and can provide numbers that work for them that I can try?


I did read this post:

I did try those suggestions, however, setting higher than 100 (step size) results in it getting way out of focus, and unable to continue.

Not certain what’s different about my setup…

I did call Starizona, and they said backlash is NOT needed on the Feathertouch/Microtouch combo, However that may not be taking the C14’s internals into account.

Any ideas?

Nobody? Still wondering what i’m doing wrong here.

Hello Lee,

It’s difficult to know what the problem might be without access to one or more SGP log files from the times when you experienced autofocus errors. I think once you provide a log or two the pros will be able to give you some advice.

Are you using a FeatherTouch that moves the primary or a crayford focuser? Anything that moves the primary mirror will absolutely need some sort of backlash compensation…a Crayford likely will not, or it will be minimal.

As Ross suggested logs would be helpful. Please see here:



First of all, I LOVE SGP… You’ve created a wonderful and useful suite.

I am not using a Crayford, but have converted the primary knob to a Feathertouch/Microtouch combo.

I’ll try to figure out exactly how much Backlash compensation i’ll need. I think when I spoke to the folks at Starizona, they did not take into account the actual Primary mirror backlash in the original Celestron factory setup, and the Microtouch/Feathertouch have almost no backlash, so it’s got to be in the original mirror focusing screw assembly. I’d have to definitely expect backlash there.

On these C14’s, in which direction should BC be applied? In or Out?

Thanks again!!

IN is almost always the way you want to go with backlash as that should move against gravity. But you’ll also want to validate that.


I use a C14 with autofocus on the primary - I use about 400 steps of backlash compensation IN. This makes the final move “uphill” taking up any slack.

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Thanks guys! That’s exactly what I was looking for!