Pegasus Astro Motor Focus Kit Zero for Celestron SCT C6, C8, C9.25, EdgeHD and RASA 8

Product Overview

The Motor Focus Kit Zero is the motor-only version of Pegasus Astro's SCT focusing hardware — the same zero-backlash bipolar stepper, bracket, pulley and belt as the FocusCube Zero, but without the built-in controller. This is the small-aperture version, cut for the Celestron C6, C8 and C9.25 Classic and EdgeHD, and the RASA 8.

Because the controller is not included, it needs one to drive it: a Pegasus Dual Motor Focus Controller, an Ultimate Powerbox v2, or an eXternal Motor Controller. If you already run one of those, this is the cheaper way onto the same mechanics.

Who It's For

This is a good match if you:

• Already own a Pegasus motor controller — a DMFC, a UPBv2 or an eXternal Motor Controller — and want to add motorised focus to a 6", 8" or 9.25" SCT.
• Image with a RASA 8, where the very short critical focus zone of an f/2 system makes hand focusing at the knob genuinely awkward.
• Are motorising a second telescope and would rather not buy a second controller for it.
• Run autofocus routines that depend on a focuser landing on the same number every time.

Key Features & Design

• Bipolar stepper, zero backlash: 1.8° step angle, 0.8 kg/cm hold torque, 0.18 kg/cm detent torque.
• Faster than the older Motor Focus Kit SCT it replaces, and free of the lash that skews an autofocus curve.
• 1:3.75 pulley ratio on the C8 and C9.25: gearing matched to the lighter focus mechanism of the smaller SCTs.
• RJ45 connection: a 1 m RJ45 cable is included for the run to your controller.
• Compact: 52 x 58 x 35 mm, 280 g including the bracket — modest to hang off a small OTA.
• Wide operating range: rated −40 °C to +80 °C.

Optical / Mechanical Design

An SCT focuses by shifting the primary mirror along the baffle tube, so focus position is set entirely by how far the knob has turned. The Motor Focus Kit Zero drives that knob through a timing belt and pulley rather than a gear train, and that choice is what produces the zero-backlash behaviour. A geared drive has lash on reversal: the motor turns, the knob does not, and the reported position no longer matches the real one. Every V-curve autofocus point built from those readings is then slightly wrong.

The RASA 8 is where this matters most in this size range. At f/2 the depth of focus is a fraction of what an f/10 SCT gives you, so the difference between in focus and visibly soft is a very small movement of the primary. A drive that lands on the same physical position every time — and a 1:3.75 ratio that divides the stepper's 1.8° step into correspondingly small increments — is what makes automated focusing practical on a system that fast.

Recommended Uses

• Adding motorised autofocus to a C6, C8, C9.25 or RASA 8 that already has a Pegasus controller on the rig.
• Fast-system imaging on the RASA 8, where the critical focus zone is short.
• Motorising a second or third telescope from an existing Dual Motor Focus Controller.
• Remote and observatory operation where focus is set from software.

Compatibility and Accessory Notes

• A controller is required and is not included. Pegasus Astro lists the Dual Motor Focus Controller, the Ultimate Powerbox v2 and the eXternal Motor Controller as the drivers for this motor. We stock those.
• This is the small-aperture bracket — Celestron C6, C8 and C9.25 Classic and EdgeHD, plus the RASA 8. The 11" and 14" versions are separate products, both of which we carry.
• Meade SCTs with the round focus knob are listed by Pegasus Astro as compatible.
• Want the all-in-one instead? The FocusCube Zero is the same mechanics with the controller built in and USB straight to the computer — the right choice if you do not already have a controller.
• Unsure which you need? Tell us what is already on your rig and we will work out whether the kit or the FocusCube is the better buy for you.

Good to Know Before You Order

• This is a motor, not a complete focus system. Without a Pegasus controller on the rig it will not move. If you are starting from nothing, the FocusCube Zero is the one-box answer.
• Aperture-specific bracket. The kit is sold per telescope size because the bracket and pulley bore differ — this one covers the 6", 8" and 9.25" and the RASA 8.
• What is in the box: the motor, the aluminium bracket, the timing belt, the pulley, screws and washers, and a 1 m RJ45 cable.
• Pegasus Astro publishes 280 g including the bracket on the Motor Focus Kit Zero page. That is well under a pound, so our declared 1 lb shipping weight is the carrier minimum rather than the true mass.

Frequently Asked Questions

Is it difficult to set up?

The mechanical fit is straightforward — bracket, pulley and belt onto the focus knob, with the screws supplied. The electrical side is one RJ45 lead to a controller you already have, and the focuser then appears in ASCOM or INDI through that controller.

Do I need to buy a controller as well?

Yes, unless you already have one. A Dual Motor Focus Controller, an Ultimate Powerbox v2 or an eXternal Motor Controller will drive it.

Does one kit really cover the C6, C8 and C9.25?

Yes — Pegasus Astro publishes it as a single part for those apertures plus the RASA 8.

How is this different from the FocusCube Zero?

Same motor and mechanics; the FocusCube Zero adds the controller electronics and a USB port, so it works on its own.

Does it come with a temperature sensor?

No. Temperature sensing comes from the controller, and the matching probe is a separate part depending on which controller you run.

Bottom Line

In short: the zero-backlash stepper, bracket, pulley and belt for a C6, C8, C9.25 or RASA 8, ready to plug into a Pegasus controller you already own. Add the controller and it becomes a full autofocus system.