Has anyone used the axis3 derotator in OnStep for imaging on an AltAzm mount?

Howard Dutton

The feature was added long ago for user/member Raymond Collecutt.

He used/uses it for planetary imaging.

Jordi Sese

Hi, this is Jordi from Barcelona.

YES, it works. I tested it yesterday for the very first time.
I have attached a (bad, it was cloudy) 240 seconds image without field rotation with a 120f5 achromat (600FL)
with an AltAz mount (a modified EQ5 turned into an AltAz) driven by OnStep 3.16 in a Mega+Ramps 1.4.

I can give you more details if you need any. I will post an image of the setup tomorrow.

Thanks a lot for making this possible, Howard and co.


Rafael Barberá Córdoba

The most strange thing of Jordi’s experiments with AltAz mounts is that he accomplished guiding with PHD2 in altaz mode. 


What hardware do you use?

Did you 3D print a gear and case?

Jordi Sese

Yes, it's a 3D printed one, with a modified (bi-polarized) 28BYJ-48 stepper motor. A more durable material would be a good idea, but hey, it works!
All the design and 3D printing was done by a good friend of mine, José A. Soldevilla. You can contact him at  if you need more details.