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IMPORTANT: Our store is located in Canada. All orders that include products manufactured outside of Canada or USA will be subject to tariffs and duties, regardless of the order value. US customers are responsible for all applicable duties and tariffs, and those will be billed by the carrier, except for the Lacerta upgrade kit, for which we collect them at checkout.

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Starlight Instruments Electronic Focusing System

SKU SI-EFS-01
Original price $300.00 - Original price $310.00
Original price
$300.00
$300.00 - $310.00
Current price $300.00
Price Match Policy!
  • ASCOM compliant driver for use with all major imaging software
  • Advanced automation including backlash and temperature compensation
  • Tactile hand controller with selectable 1, 10, or 100-step increments
  • Compact control box measures just 4.13" x 2.87" x 1.1"
  • Compatible with HSM20, HSM30, and HSM35 stepper motors
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  • Description
  • FAQ
  • Specifications
  • In the Box
  • Downloads
  • Warranty
  • Starlight Instruments Electronic Focusing System (EFS)

    The Starlight Instruments Electronic Focusing System (EFS) is a dedicated ASCOM-compliant stepper motor controller designed for absolute focusing precision. Its compact control hub measures just 4.13" long by 2.87" wide, providing advanced features like temperature compensation and backlash correction without adding bulk to your imaging rig. The included hand controller allows for immediate tactile adjustments, with selectable step sizes of 1, 10, or 100 steps per detent for moving from coarse focus to critical final tweaks.

    The 4.13" x 2.87" ASCOM-Compliant Digital Hub

    At the core of the EFS is a lightweight and robust digital hub that serves as the interface between your PC and focuser motor. It connects via a standard USB cable and is managed by a dedicated ASCOM driver, ensuring seamless integration with virtually all modern astrophotography software suites like N.I.N.A., Sequence Generator Pro, and TheSkyX.

    The hub's small 4.13" x 2.87" x 1.1" footprint makes it ideal for portable setups where space and weight are critical. All connections are logically placed, with power, USB, and hand controller inputs on the rear and the motor output on the front, keeping cable management clean and simple.

    Intuitive Hand Control: 1, 10, and 100-Step Adjustments

    For moments when you need direct, computer-free control, the EFS includes a tactile hand controller. A simple press of the central knob cycles through three resolution levels, indicated by an LED: Red for 1-step fine adjustments, Amber for 10-step increments, and Green for 100-step coarse movements. This allows you to quickly rack the focuser out to change eyepieces and then dial in perfect focus without ever touching your laptop.

    Automated Focusing: Temperature and Backlash Compensation

    The EFS is built for serious imaging. Its ASCOM driver enables sophisticated automation routines that directly address the two most common causes of soft stars during a long session. Backlash compensation ensures your autofocus V-curves are perfectly symmetrical and repeatable, while temperature compensation uses an external probe to automatically adjust focus as ambient temperature drops, maintaining sharp stars from dusk till dawn.

    EFS vs. Focuser Boss II: A Guide to Starlight Instruments Controllers

    Starlight Instruments offers two electronic focusing controllers, each tailored to different needs. The EFS is the streamlined, single-focuser solution perfect for portable rigs or dedicated single-scope imagers. It provides all the essential automation features in a compact, cost-effective package.

    The Focuser Boss II, by contrast, is a full observatory-grade hub. It offers dual-focuser control, native Ethernet and optional WiFi connectivity for remote access, and a more expansive feature set for permanent installations. For imagers who need a simple, robust, and precise single-channel controller, the Electronic Focusing System is the optimal choice.

  • What software is compatible with the Starlight Instruments EFS?

    The Electronic Focusing System uses an ASCOM driver, making it compatible with any software that adheres to the ASCOM standard. This includes popular astrophotography applications like N.I.N.A., Sequence Generator Pro (SGP), TheSkyX, Maxim DL, and more.

    Which Starlight Instruments motor do I need for my EFS and telescope?

    The correct motor depends on your focuser. The EFS is compatible with all Starlight Instruments HSM motors.

    • HSM20: Fits Feather Touch Micro Focusers, retrofit pinion assemblies, and Crayford focusers.
    • HSM30: Fits 2.5", 3.0", and 2.0" Rack/Pinion focusers, as well as Astro-Physics 2.7" focusers with the Feather Touch upgrade.
    • HSM35: Fits 3.5" Feather Touch focusers, and Astro-Physics 3.5" and 4.0" focusers with the Feather Touch upgrade.

    How does the EFS hand controller change step sizes?

    You can change the step size by pressing the knob on the hand controller. Each press cycles through the three settings, which are confirmed by a colored LED light: Red for 1 step, Amber for 10 steps, and Green for 100 steps per detent.

    Can the Starlight Instruments EFS run without a computer?

    Yes. While its advanced automation features require a computer running ASCOM software, the EFS can be operated manually for visual use or initial setup using only the included hand controller and a power source. This allows you to achieve precise focus at the eyepiece without being connected to a PC.

    I'm imaging the Andromeda Galaxy (M31) with my C11. How does the EFS prevent focus drift as it gets colder?

    The EFS features temperature compensation. When used with a temperature probe, the system monitors ambient temperature changes throughout your imaging session. As the telescope's optical tube contracts in the cold, the EFS automatically makes micro-adjustments to the focus position to counteract the thermal shift, ensuring your stars remain pinpoint sharp on every sub-exposure.

    When running an autofocus routine in N.I.N.A. on my refractor, how does the EFS ensure accuracy?

    The EFS driver includes backlash correction. This feature commands the motor to overshoot a target position and then approach it from the same direction every time, eliminating any mechanical play or "slop" in the focuser's gear train. This results in highly repeatable V-curves and ensures your autofocus routine calculates the critical focus zone with maximum accuracy.

  • Motor Compatibility (HSM20) Feather Touch Micro Focuser, retrofit pinion assembly upgrades, and Crayford focusers
    Motor Compatibility (HSM30) 2.5", 3.0" & 2.0" Feather Touch Rack/Pinion focusers; Astro-Physics 2.7" with FT pinion upgrade
    Motor Compatibility (HSM35) 3.5" Feather Touch focusers; Astro-Physics 3.5" & 4.0" with FT pinion upgrade
    Control Box Dimensions 4.13" (105mm) L x 2.87" (73mm) W x 1.1" (28mm) H
    Connections Power, hand controller, USB (rear); focuser (front)
    Software ASCOM driver (requires ASCOM Platform 6 or later)
    Hand Controller Step Sizes 1, 10 or 100 steps per detent
    Automated Features Backlash correction, temperature compensation, focus lock, motor braking, multiple speeds
    Power Options AC/DC Power Supply 12V DC, DC Cigarette Plug, European Power Adapter (selected at purchase)
    • EFS Control Hub

      × 1

    • EFS Hand Controller

      × 1

    • USB Cable (A to B)

      × 1

    • Ethernet Cable (Hub to Motor)

      × 1

    • RJ11 Cable (Hub to Hand Controller)

      × 1

    Note: A compatible Starlight Instruments HSM motor and a 12V DC power supply are required and sold separately.

  • Starlight Instruments 1-Year Warranty on Electronics