Celestron Electronic Focus Motor For SCT and EdgeHD


Availability: More on the way

The Celestron Focus Motor for SCT and EdgeHD enables electronic focusing using a computer or Celestron computerized mount hand controller for remote/hands-free observing.

Self-powering: When connected to a Celestron computerized mount, the mount provides the power. When connected directly to a computer, USB provides the power.

Compatible with a wide variety of Celestron Schmidt-Cassegrain, EdgeHD, and Rowe-Ackermann Schmidt Astrograph optical tubes.

Motor controls include multiple speed rates, automatic GoTo indexed focuser position, and focuser backlash compensation.

Focuser Utility software for Windows provides a simple user interface. Also compatible with Celestron PWI.

Enables autofocusing with a camera and third-party software via ASCOM.

Indexed focus position allows the motor to automatically return to a previous focus position and prevents the focus motor from reaching the end of telescope’s mechanical focus travel.

Our Product #: 94155
Celestron Product #: 94155-A
Recommended Accessories

Product Description

The Focus Motor for SCT & EdgeHD provides electronic focusing for Celestron Schmidt-Cassegrain (SCT) and EdgeHD telescope optical tubes. With the focus motor installed, you can bring celestial objects into sharp, precise focus using your telescope’s hand controller or a computer instead of using the focuser knob. A focus motor is great for visual observers who want to dial in exact focus (especially those with dexterity issues) and a must-have accessory for astroimagers. With a motorized focuser installed, an astroimager no longer needs to be physically near the telescope to focus an image. Combined with computerized control of the mount and camera, the focus motor enables the imager to gather data remotely from a backyard observatory, or even a telescope located hundreds of miles away. As an added bonus, port covers protect the ports while not in use, and the covers cannot be lost due to the tethered design.

Compatible Optical Tubes

The focus motor is compatible with all SCTs from 6” to 14” in aperture that have been produced since the year 2006. It is not compatible with 5” SCTs or older models. It is compatible with all EdgeHD optical tubes, the 8” Rowe-Ackermann Schmidt Astrograph (RASA), the 36cm RASA, and the 7” Maksutov-Cassegrain. It can also be used with the 11” RASA, but requires the Focuser Retrofit Kit for RASA 11.

Power Options

There are three options for powering your Celestron Focus Motor:

When using a Celestron computerized mount, you can power and control the focus motor through the mount using the supplied AUX cable. This allows control from the mount’s hand controller (NexStar+ or StarSense) or a computer.

If you are not using a Celestron mount, you can power and control the focus motor from a computer USB port. You will need a user supplied USB A-to-B cable.

You may also opt to use an external 12V DC power source which plugs into the motor’s power jack.

Compatible Software

Celestron offers a free Focuser Utility program for computer control. The Celestron PWI software can also control the focus motor. To use third-party focuser control software, an ASCOM driver is needed.

Motor: DC servo motor

Spur gears Brass: 1:1 gear ratio, 38mm diameter, 45 teeth

Focuser shaft coupler: Aluminum clamping sleeve

Microprocessor: NXP Kinetis series, Arm Coretex-M4 core

AUX port power: Powered by Celestron computerized mount AUX port, connecting cable supplied

USB port power: USB3 or USB2 providing at least 900mA

DC jack power: 12V DC, 1A, 5.5mm/2.1mm tip positive plug

Compatibility: All SCTs produced after 2006 except 5" SCT, all Edge HD, RASA 8", RASA 36cm, 7" Mak-Cass

Speed rates: 8°/sec , 32°/sec , 128°/sec

Tech Details


Review by:
Adding the Celestron Focus Motor to my Nexstar 8SE was one of the best things I've done. I really like the ability to focus without touching the scope as my shaky hands would introduce vibrations and I'd have to wait a few seconds every time I made an adjustment. No more! I just focus from the hand controller and have no more shakes. Another benefit is that you can go to a specific focus position. So when you change eyepieces and you've noted the proper focus position, you can easily get back to that exact spot next time. (Posted on 10/24/2019)
Review by:
Bought this product eight months ago. The physical install was less than seamless, as over tightening the mounting screws caused it to bind up multiple times. After several questions on cloudy nights and multiple replies, the mechanism seems to work. Next problem arose when trying to use it via the AVX handset. During calibration the handset returns “No response 18” error, and then just continues to run back-and-forth endlessly. Celestron has no fix for this. Ultimately, the focuser does work via USB with the standalone Celestron app. Hopeful it will work well for the coming fall and some AP. We will see... (Posted on 10/19/2019)
Review by:
As of now, this has been a huge headache and a bigger disappointment - stay away
Purchased for my C8 on an AVX mount, my first serious astro rig which is only 2 years old.

the physical Install was fairly easy, except when you discover that it doesn't take much to "over tighten" any of the screws to cause binding.  I do mean it doesn't take much.  I fumbled around with loosening and tightening to get the right combo for a few hours.  Back off a screw less than a quarter turn and it all moves freely but the screws are loose and the whole focuser wobbles about.  Finger snug the screws and its too tight the focuser would barely move before binding up.  One suggestion from Celestron was to use the original focus collar as a spacer on top of the focus motor collar, i have not done this yet so not sure if it works.  

The software portion has been just as fun.  The only bit of software that seems to reliable work is the supplied focus motor utility app, but only if you connect to it directly through USB i.e. computer - usb - focuser.  Outside of that, good luck getting it to work via ASCOM with CPWI or SharpCap, maybe you could but you'd have to follow one of 30 different combinations of "power this on first then that, then plug the USB only to this or that, then..." Its  a big mess honestly.  Ive update all my Celestron gear to the latest greatest firmware and software packages from Celestron that allegedly support their own focus motor only to find it kinda works sometimes.  No matter which way I connect to my mount or focuser it will loose ASCOM connection shortly after.  As if all this wasn't enough fun, now my AVX mount does some of the weirdest maneuvers when its slewing that half the time i have to cut power to it before it crashes into itself.

Good Luck

(Posted on 10/14/2019)
Review by:
Bought this and installed on my SCT 9.25 scope mounted on a CGX mount.
Easy to mount on my scope with supplied adapter plate.
But I was very careful not to over tighten then mount plate screws in case there were alignment issues from the plate warping on the mount.
The motor split collar main screw does not provide enough force to firmly squeeze the adapter collar on the focuser shaft , therefore it is critical to tighten the secondary set screw in the motor collar to achieve positive rotation of the focus shaft. BUT, do not apply excessive torque, just enough to make sure you get good rotation without slipping.
The celestron stand alone control program works very well.
They also provide a ASCOM interface for interfacing with many imaging programs.
Overall a very nice product. (Posted on 7/22/2019)
How do you rate this product? *