iAFS2 and iAFS3 auto focusers

Posted on Wednesday, March 19, 2025 by RICHARD HARRIS, Executive Editor

iOptron’s latest auto focusers, the iAFS2 and iAFS3, offer high-precision electronic focusing with zero backlash, ASCOM/INDI compatibility, dual USB-C ports, and built-in Camera Angle Adjusters. The iAFS2 is a 2-inch model, while the iAFS3 features a larger 3-inch design with enhanced load capacity and iLock technology for secure positioning.

iAFS2 and iAFS3 auto focusers from iOptron

Both include high-resolution stepper motors, temperature compensation, and position memory for consistent focusing. Ideal for astrophotography, these focusers provide smooth, automated operation with flexible control options, making them a valuable upgrade for telescopes across various optical setups.

iOptron iAFS2 auto focuser features and specifications

  • High Precision Stepper Motor: The iAFS2 is equipped with a high-precision stepper motor that ensures accurate focusing. The design incorporates position over-run protection to prevent damage and maintain optimal performance.
  • Built-in Temperature Sensor: A built-in temperature sensor allows for real-time monitoring of environmental conditions, facilitating temperature compensation during auto-focusing. This feature helps maintain focus accuracy despite temperature fluctuations.
  • Compact and Lightweight Design: Weighing approximately 783 grams and measuring 90.5 x 106 x 82 mm, the iAFS2 is both compact and lightweight. Its streamlined design minimizes unnecessary components, making it suitable for various telescope setups without adding significant weight.
  • Zero Backlash: The focuser's design ensures zero backlash, providing smooth and accurate focusing adjustments without delays or errors.
  • Dual USB-C Ports: The inclusion of dual USB-C ports facilitates easy connection to computers for control and firmware upgrades. This feature ensures compatibility with modern devices and simplifies the setup process.
  • ASCOM and INDI Compatibility: The iAFS2 is compatible with both ASCOM and INDI platforms, allowing integration with a wide range of astronomical software and equipment.
  • Manual Adjustment: Users can perform manual adjustments whether the focuser is powered or unpowered, offering flexibility during observations. The manual focusing knob allows for quick adjustments without relying solely on electronic controls.
  • Position Memory: The focuser memorizes its position during power-off, ensuring that focus settings are retained between sessions. This feature is particularly useful for maintaining consistency in imaging sessions.
  • Built-in Camera Angle Adjuster (CAA): A high-precision CAA is integrated into the focuser, enabling easy image alignment and composition adjustments. This feature enhances the user’s ability to frame celestial objects accurately.
     

iOptron iAFS2 specifications

  • Focuser: Inline Auto Focuser with iLock
  • Focuser Size: 2"
  • Dimensions: 90.5 X 106 X 82mm
  • Weight: 783g
  • Clear Aperture: 51mm
  • Maximum Payload: 11lbs / 5kg
  • Drawtube Travel Distance: 30mm
  • Focusing Resolution: 0.6um
  • Power/Communication Port: USB2.0 Type-C port X2
  • Driving Train: Stepper motor
  • Computer Control: Yes (ASCOM and INDI)
  • Automatic Focusing: Yes
  • Motorized Focusing Button: Yes
  • Manual Focusing: Yes (w or w/o motor power on)
  • Temperature Sensor: Yes (Built-in)
  • Camera Angle Adjustment: Yes
  • Warranty: One year limited
     

The iAFS2 is compatible with most Optical Tube Assemblies (OTAs) when used with the appropriate adapter. Optional adapters are available for various telescope models, including:?

  • Askar/65PHQ and Other M80X1 Threads: The P-FA20-M0800 adapter allows the iAFS2 to be attached to telescopes with M80X1 threads, such as the Askar 65PHQ.
  • Celestron/C11 and Other M83.5X1.5 Threads: The P-FA20-M0835 adapter facilitates compatibility with telescopes featuring M83.5X1.5 threads, including models like the Celestron C11.
  • GSO/RC6, RC8, and Other M90X1 Threads: For telescopes with M90X1 threads, such as the GSO RC6 and RC8, the P-FA20-M0900 adapter is available.
  • M48X0.75 Camera Adapter: The P-FA20-CA adapter allows for the attachment of cameras with M48X0.75 threads, broadening the focuser's versatility for astrophotography.
     

The standard package of the iAFS2 includes:

  • iAFS2 2" Focuser: The main focuser unit equipped with advanced features for precise focusing.?
  • 2" Visual Back (P-FA20-VA): A visual back adapter that allows for the attachment of various accessories and eyepieces.?
  • USB2.0 (Type-C) Cables: Two USB-C cables are provided for connection to computers and for firmware upgrades.?
     

The iAFS2's quiet and smooth operation ensures minimal disturbance during observations, and the fast response time allows for quick focusing adjustments. The focuser's ability to handle payloads up to 11lbs makes it suitable for a wide range of optical setups.

Compatibility with ASCOM and INDI drivers allows the iAFS2 to integrate seamlessly with popular imaging software. This integration enables automated focusing routines, enhancing the efficiency of imaging sessions. The built-in temperature sensor provides data for temperature compensation, ensuring consistent focus despite environmental changes.

The iAFS2 offers flexibility with both manual and motorized focusing options. The manual focusing knob allows for tactile adjustments, while the motorized controls provide precision through computer interfaces or onboard directional buttons. This dual functionality caters to both traditional observers and those utilizing automated systems.

Installing and setting up the iOptron iAFS2

Installing the iOptron iAFS2 is a straightforward process designed for convenience. The focuser is compatible with various telescope setups, and with the appropriate adapter, it can be attached to a range of optical tubes. Users simply need to secure the focuser onto their telescope's drawtube using the designated adapter. Once mounted, the device can be connected to a power source and computer via USB-C for full functionality.

To maximize efficiency, users should install the necessary ASCOM or INDI drivers for software integration. The stepper motor system allows for precise electronic control, but manual adjustments can still be made if needed. Calibration of the focuser’s position is recommended during the initial setup to ensure accurate focusing.

Astrophotographers and visual observers alike will appreciate the iAFS2’s performance in real-world applications. Its zero-backlash stepper motor provides ultra-precise movements, ensuring that even the smallest focus adjustments are registered accurately. The ability to retain focus position between sessions enhances imaging consistency, which is particularly useful for long-exposure astrophotography.

Temperature fluctuations can often lead to focus drift, but the iAFS2's built-in temperature sensor mitigates this issue. By automatically compensating for temperature changes, the focuser ensures stable and sharp images throughout extended observing sessions.

Users have reported that the iAFS2 is exceptionally quiet in operation, producing minimal vibrations. This is particularly beneficial when capturing images at high magnifications, as even the slightest disturbance can affect image quality. The quick response time of the focuser also allows for rapid adjustments, which is crucial when tracking fast-moving celestial objects.

The iAFS2's automated focusing capability allows for hands-free operation, eliminating the need to constantly adjust focus manually. When paired with popular imaging software such as Sequence Generator Pro (SGP) or NINA, users can execute automated focusing routines, further enhancing the efficiency of imaging sessions.

The inclusion of a Camera Angle Adjuster (CAA) provides an added advantage for astrophotography. This feature allows users to rotate their camera setup with high precision, ensuring optimal framing of celestial objects. Combined with the stepper motor’s pinpoint accuracy, the iAFS2 significantly reduces the likelihood of soft-focus images, even in deep-sky astrophotography.

Additionally, the focuser’s ability to handle payloads up to 5 kg ensures compatibility with larger imaging setups. This makes it a suitable choice for astrophotographers using heavy cameras and filter wheels.

The iOptron iAFS2 2" Inline Automatic Focuser: In summary

The iOptron iAFS2 2" Inline Automatic Focuser is a powerful and reliable focusing solution for both astrophotography and visual astronomy. With features like zero backlash, a built-in temperature sensor, position memory, and ASCOM/INDI compatibility, it offers outstanding value for its price. While minor drawbacks such as the need for separate adapters and the lack of wireless connectivity exist, the overall performance and build quality of the iAFS2 make it a standout choice for anyone looking to improve their telescope’s focusing capabilities. Overall, the iAFS2 is a well-rounded, high-performance automatic focuser that will be a valuable addition to any serious astronomer's setup. Its combination of advanced features, ease of use, and affordability makes it a compelling choice for those looking to enhance their observational and imaging experience.


iAFS3 3" Inline Automatic Focuser

iOptron has expanded its lineup with the iAFS3 3" Inline Automatic Focuser, offering a larger format for those needing increased load capacity and stability. This electronic focuser features a patented passive locking mechanism for secure positioning, a high-resolution stepper motor for precise adjustments, and versatile control options for seamless integration into astrophotography setups. The iAFS3 ensures smooth and consistent focusing performance, and below we take a closer look at its key features, what's included, and the specifications.

iOptron iAFS3 auto focuser features

  • High precision stepper motor with position over-run protection
  • Built-in temperature sensor
  • Built-in CAA
  • Quiet, smooth, fast operation
  • Compact and lightweight
  • Zero backlash
  • Dual USB-C port for computer connection and firmware upgrade
  • ASCOM and INDI compatible
  • Low power consumption with USB2.0 (type-C) powering
  • Manual adjustment (powered or unpowered)
  • Position memorizing during power off
  • Compatible with most OTAs with proper adapter
     

Package includes

  • 1X iAFS3 3" focuser
  • 1X 2" Visual Back (P-FA30-VA)
  • 2X USB2.0 (Type-C) cable
     

Adapters

P-FA30-M1170: iAFS3 telescope adapter GSO/RC10,12,14,16 and other M117X1

  • Description: iOptron iAFS 3" auto focuser system M117X1 telescope adapter for GSO RC10,RC12,RC14,RC16 and others.
  • Price: $48.00
     

P-FA30-CA: iAFS3 camera adapter M68X1

  • Description: M48 Camera Adapter for iAFS 3" auto focuser system.
  • Price: $25.00
     

The iAFS3 features a uniuqe iLock mechanism. This technology ensures that once the focuser stops moving, it passively locks in place. Unlike traditional focusers that may suffer from unwanted shifts due to gravity or mechanical backlash, the iAFS3 maintains its position with absolute accuracy. This feature is especially beneficial when using heavy imaging equipment, as it prevents any drift in focus.

The heart of the iAFS3 is its high-precision stepper motor, designed to deliver incredibly fine focus adjustments. This motor-driven system not only enhances accuracy but also includes built-in position over-run protection, preventing unintended movements that could disrupt the imaging process.

With a remarkable focusing resolution of 0.6 microns, the iAFS3 ensures that even the smallest changes in focus are handled with extreme precision. This level of detail is crucial for capturing sharp images, especially in deep-sky astrophotography, where focus accuracy can make or break an image.

Temperature fluctuations can cause subtle yet significant changes in focus, particularly over long imaging sessions. The iAFS3 combats this issue with a built-in temperature sensor that actively monitors ambient conditions. By compensating for temperature-induced focus shifts, it helps maintain perfect focus throughout the night, reducing the need for manual adjustments.


iOptron iAFS3 specifications

  • Focuser: Inline Auto Focuser with iLock
  • Focuser Size: 3"
  • Dimensions: 94 X 133 X 108mm
  • Weight: 1062g
  • Clear Aperture: 68mm
  • Maximum payload: 6kg
  • Drawtube Travel Distance: 30mm
  • Focusing Resolution: 0.4um
  • Power/Communication Port: Type-C USB2.0 port X2
  • Driving train: Stepper motor
  • Computer Control: Yes (ASCOM and INDI)
  • Automatic Focusing: Yes
  • Motorized Focusing Button: Yes
  • Manual Focusing: Yes (with override)
  • Temperature Sensor: Yes (Built-in)
  • Camera Angle Adjustment: Yes
  • Warranty: One year limited
     

Flexibility in control is a major advantage of the iAFS3. It offers three distinct movement control modes, catering to different user preferences:

  • USB Control: The focuser can be operated via a computer using ASCOM and INDI-compatible software. This option is perfect for remote astrophotography setups where manual access is limited.
  • Onboard Directional Buttons: For users who prefer direct interaction, the built-in buttons allow for powered manual adjustments without needing a computer.
  • Manual Focus Wheel: A traditional manual focus knob remains available, providing an override option for astronomers who prefer a hands-on approach.
     

The iAFS3 features an all-metal body with a fingerprint-resistant finish, it is designed to withstand harsh observing conditions while maintaining a sleek and professional appearance. The solid construction ensures longevity, making it a reliable investment for serious astronomers. Modern connectivity options make the iAFS3 highly adaptable to various setups. It includes dual USB-C ports, allowing for flexible data transfer and firmware upgrades. This design choice simplifies integration into existing imaging rigs while ensuring future-proof compatibility with evolving technology.

Astrophotographers often need to fine-tune their camera's orientation to frame their target properly. The iAFS3 addresses this need with a built-in Camera Angle Adjustment (CAA) feature, enabling users to rotate their camera without affecting focus. This makes it easier to achieve the perfect composition for astrophotography sessions. To protect both the focuser and the telescope, the iAFS3 includes position limiters. These safeguards prevent the drawtube from exceeding its mechanical limits, reducing the risk of damage to delicate optical components.

The iOptron iAFS3 3" Inline Automatic Focuser: In summary

The iOptron iAFS3 3" Inline Automatic Focuser is a game-changer for astronomers seeking the highest level of precision and reliability in their focusing systems. Its combination of advanced features, including iLock technology, a high-precision stepper motor, temperature compensation, and versatile control options, sets it apart from traditional focusers. With its robust construction, multiple connectivity options, and adaptability to various telescope systems, the iAFS3 is a must-have tool for both amateur and professional astronomers. Whether used for deep-sky imaging, planetary observation, or remote observatory setups, this focuser ensures that achieving perfect focus is easier and more reliable than ever before.

iOptron iAFS 2 - Exclusive First Look at This Revolutionary Inline Focuser!

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