Starlight Instruments Feather Touch Micro Focuser for Celestron CPC11, C11 Edge HD SCT

Dual-Speed 10:1 Focusing

The Feather Touch Micro Focuser gives two focusing speeds: the black coarse knob and the brass fine knob at a 10:1 ratio, so ten turns of the fine knob equal one turn of the coarse knob. That makes small, deliberate adjustments much easier than with the single-speed stock knob.

The Micro Focuser still moves the primary mirror, so image shift from the mirror remains; the gain is fine focus without the coarse jumps of the stock knob. Ultra-smooth coarse and fine knobs and an ultra-low backlash system are among the Feather Touch standard features.

Why Fine Focus Matters on a Schmidt-Cassegrain

A long focal length telescope like an 11-inch SCT creates a very narrow critical focus zone, the small range where the image is sharp. A single-speed knob moves the mirror a long way for a small turn, so it is easy to go past best focus.

The 10:1 fine control of the Feather Touch allows you to methodically approach and settle into the critical focus zone. That helps whether you are focusing a camera or looking for the sharpest view of a planet.

Compatibility: CPC-1100 and C11 EdgeHD

The FTM-CPC11 is for the Celestron CPC-11 and C11 EdgeHD. If your telescope is less than a few years old, the style of the back cell shows which version you need: a triangular pattern on the back needs the "CPC" version, and a flat back needs the standard "C" version.

• Correct Fit: Celestron CPC-1100 and C11 EdgeHD models with a triangular pattern on the rear cell.
• Not this version: a Celestron 11" telescope with a flat back cell takes the standard "C" version of the Micro Focuser.

Feather Touch FTM-CPC11 vs. Stock Celestron Focuser

The Feather Touch replaces the single-speed stock knob assembly with a dual-speed one.

• Focus Control: The stock focuser is single-speed and coarse. The Feather Touch FTM-CPC11 provides a dual-speed 10:1 ratio, for small adjustments with a camera or at high power.
• Mirror: both still focus by moving the primary mirror, so the Feather Touch does not remove image shift; it lets you reach focus without the coarse jumps of the stock knob.
• Construction: Hardened stainless steel, steel and aluminum construction and ultra-smooth coarse and fine knobs are among the Feather Touch standard features.

Installation in Eight Steps

You need a Phillips screwdriver and a 1/2" or adjustable wrench. Position the optical tube horizontally before removing the original focus assembly, or the primary mirror could move.

Pull off the black rubber knob, remove the three screws of the orange focus assembly cover (keep them), turn the brass part clockwise to bring the mirror back and remove the screw and washer at the end of the focus shaft. Turn the brass part counterclockwise, quite a few turns, to remove the bearing assembly. Thread the Feather Touch stop onto the focus shaft and refit the screw, using the washer supplied with the FTM-CPC11 instead of the stock one (Starlight's addendum: the stock washer may cause binding). Thread the Micro Focuser into the stop, tighten the stop with the wrench, run the focuser down until it sits flush and attach it with the three original screws. Expect the telescope to be far out of focus at first.

Motorizing Your Focuser: The HSM20

The Handy Stepper Motor (HSM20) fits any Feather Touch Micro Focuser, with separate installation instructions for the Micro Focuser.

Run by a Starlight Focuser Boss II or EFS controller, it allows computer-controlled focusing through ASCOM software, with temperature compensation using the motor's built-in thermistor. The HSM20 is sold separately.

Built in the USA: Starlight Instruments Construction

Starlight Instruments designs, machines, anodizes and assembles its Feather Touch components in-house in the USA. The brochure lists durable hardened stainless steel, steel and aluminum construction and an anodized aluminum fine focus knob among the Feather Touch standard features.