Starlight Instruments Feather Touch 3.0" R&P Focuser

Helical Rack & Pinion: A 13-15 Pound Lifting Capacity

The core of the Feather Touch 3.0" Focuser is its robust helical rack and pinion drive. The helical rack and pinion gives smoother operation, increased carry loads and virtually zero backlash, and the 3.0" focuser is rated at 13-15 pounds.

To further secure the imaging train, a brake thumbscrew on the underside of the pinion assembly provides a locking mechanism to prevent any unwanted drawtube movement. Prolonged use with the brake engaged may wear the internal brake component prematurely.

Feather Touch 3.0" R&P vs. Crayford Focusers: Why The Drive System Matters

A Crayford focuser moves the drawtube by friction; a rack and pinion drives it through gear teeth. The Starlight 2" Crayford is rated at 8-10 pounds and the 2.5" and 3.0" rack and pinion focusers at 13-15 pounds.

• Positive Engagement: The helical rack on the underside of the drawtube meshes with the pinion.
• Load Capacity: 13-15 pounds, against 8-10 pounds for Starlight's 2" Crayford.
• Low Backlash: The operation has virtually zero backlash, which helps when a motor drives the focuser.

1.5", 2.5", and 3.5" Travel Options for System Matching

The Feather Touch 3.0" Focuser is available in three distinct drawtube travel lengths to match the specific needs of your optical system. The variants are 1.5" (38.1 mm), 2.5" (63.5 mm) and 3.5" (88.9 mm); choose the travel that covers the focus positions of your eyepieces and imaging accessories.

The 2.5" and 3.0" focusers have the same 13-15 pound lifting capacity in all three travels.

The 10:1 Planetary Reduction and Brake System

The acclaimed Feather Touch dual-speed system provides a 10:1 reduction ratio, translating ten turns of the fine-focus knob into one turn of the coarse knob. This level of control is essential for high-resolution imaging where the critical focus zone is exceptionally narrow. The friction-based planetary reduction assembly has a stainless steel housing, high grade stainless steel ball bearings in a brass cage and a tool steel reduction pin; its tight tolerances give smooth operation with virtually zero backlash.

The brake thumbscrew, located on the pinion assembly, locks the drawtube to prevent unwanted movement from gravity. Minor focus adjustments with the fine focus knob can be made after locking, but prolonged use with the brake engaged may wear the internal brake component prematurely.

Full 360° Rotation in a PTFE-Lined Adapter

The entire focuser body rotates a full 360 degrees within its telescope-specific tube adapter (sold separately). This feature is indispensable for astrophotography, allowing you to frame your target perfectly without rotating your entire imaging train. Simply loosen the three nylon-tipped thumbscrews, orient your camera to capture the ideal composition, and lock it back down.

The tube adapter is PTFE lined and contains a nylon ring the focuser rests against, and the gold thumbscrews are nylon tipped so they do not damage the housing. For large asymmetrical loads such as heavy motor drives, stainless steel tipped thumbscrews are available. This system also lets you position the focus knobs for comfortable access regardless of your telescope's orientation on the mount.

A Modular System: Telescope Adapters and End Caps

The Feather Touch 3.0" uses interchangeable tube adapters and end caps, which are purchased separately.

• Tube Adapters: In most cases the adapter screws onto the telescope; on some (such as carbon fiber tubes) it is secured with screws. Options include the A30-1903-1 standard tube adapter ring and telescope-specific rings such as the A30-1903-26 for the Tele Vue 127is.
• End Caps: Options include the EC30-1905-1 standard 2.0" compression ring end cap and threaded end caps: 3.0x24 TPI for cameras and filter wheels, 2.7x24 TPI Astro-Physics, M68x1, M48x0.75, M65x1 for the Sky-Watcher corrector, M72x1 Takahashi, M82x1 for the Riccardi reducer and M92x1 William Optics.

Drawtube Engineering: Millimeter Scale and Anti-Reflection Baffling

Designed for the data-driven imager, the Feather Touch 3.0" drawtube includes features for precision and contrast. A millimeter scale is marked on the side, allowing you to return to precise focus points for different filters or cameras.

Inside, the drawtube features glare-resistant black baffling. This surface absorbs stray light that would otherwise reduce contrast and wash out faint details in your images.

User Adjustments: Tension, Brake, and End Cap Collimation

The Feather Touch 3.0" Focuser provides several points of adjustment to tune its performance to your exact payload. The drawtube tension nut (3/16 hex key) sets the drag on the drawtube; keep at least light tension to prevent drawtube tilt and image shift. A second tension nut under the adapter is factory set and should not be adjusted. The brake provides a hard lock for heavy payloads, while the end cap (sold separately) typically features three set screws for collimation.

To collimate, loosen the three set screws on the end cap face with a 1/16 hex key, unscrew the end cap about 1/4 turn, adjust the tilt and tighten the same screws. Removing tilt helps keep stars round across the field.

Automation Ready: Motor Upgrade Paths with HSM and PDMS

The Feather Touch 3.0" Focuser is designed for seamless integration with Starlight Instruments' motorization systems (sold separately). The HSM30 fits any 3.0" Feather Touch rack and pinion focuser, and the PDMS is available for heavier image trains.

Either motor is run by a Starlight controller (Focuser Boss II or EFS, sold separately) through ASCOM; the EFS adds temperature compensation. The focus knobs come off with a 1/16 hex key for the motor installation, and the manual warns to keep the inner workings clean once they are off.

Materials and Craftsmanship: Machined in the USA

Every Feather Touch focuser is designed, machined, anodized, and assembled in-house at Starlight Instruments' facility in the USA. The focuser is built from hardened stainless steel, steel and anodized aluminum.

• Reduction Assembly: Its tight tolerances give smooth operation with virtually zero backlash (manual).
• Finderscope Mounting: Two sets of #8-32 UNC threaded holes, fitted with filler screws, take a finderscope base and bracket (sold separately); with third-party bases, use screws that are not too long or they can damage the drawtube.
• Accessory Protection: Starlight uses tipped stainless steel set screws, gentle on eyepieces.

Step-by-Step Installation Guide

Installing the Feather Touch 3.0" Focuser is a straightforward process. First, separate the tube adapter from the focuser body by loosening the three gold thumbscrews. This makes handling the individual components easier.

After removing your telescope's stock focuser, attach the Feather Touch tube adapter (sold separately); in most cases, it simply screws into place, but on some telescopes (such as carbon fiber tubes) it is secured with screws. Once the adapter is secure, reinsert the focuser body, rotate it to your desired orientation, and tighten the three thumbscrews to lock it in position. You can then attach your end cap and collimate if necessary.