SESTO SENSO 3 robotic focusing motor for external focusers

SESTO SENSO 3 is our most advanced robotic focusing motor for rack-and-pinion or Crayford-style focusers, combining high precision, flexibility, and ease of use in a compact design. Developed and manufactured in Italy by PrimaLuceLab, it introduces key innovations such as the integrated position encoder, which allows manual movement of the focuser without losing motor position with Automatic Position Recovery option, and the new Self Centering Clamp 2 (SCC2) for fast installation to many focusers without external brackets or adapters.

With USB-C and built-in WiFi connectivity, you can control SESTO SENSO 3 from your computer or wirelessly via the Virtual HandPad using a smartphone or tablet. Its high-precision motor delivers 0.7 micron per step resolution, making it ideal for both visual observation and astrophotography. Compatible with ARCO rotators, ASCOM drivers, and PLAY software, and supporting EAGLE’s GHOST mode, and DARK mode with dimmable LED lights, SESTO SENSO 3 sets a new standard in robotic focusing systems.

SESTO SENSO 3 is our most advanced robotic focusing motor for external focusers like Crayford or Rack-and-Pinion

SESTO SENSO 3 is the most advanced robotic focusing motor for external Crayford or Rack-and-Pinion focusers. Built upon the success of the first and second generation motors, the SESTO SENSO 3 adds even more amazing new features, incorporated into a single enclosure to house all the elements that comprise a motorized focusing system:

SESTO SENSO 3 robotic focusing motor for external focusers - main features:

• NEW Compact all-in-one chassis designed to be installed on external Crayford and Rack-and-Pinion focusers
• NEW Integrated encoder for position tracking and manual movement without losing motor position with Automatic Position Recovery option
• NEW Self Centering Clamp 2 (SCC2) for fast installation without brackets or other adapters to focusers with 25mm, 26mm, 33mm and 37mm shafts
• High precision motor with 0.7 micron resolution per step (on focusers with 1:10 reduction)
• USB-C connectivity to control from computers with astronomy software
• WiFi connectivity to control it from smartphone or tablet with the included Virtual HandPad, without the need of computer or physical hand pad
• Compatible with PLAY software to control focus position, also with autofocus
• Provided with ASCOM drivers to let you control through third party astronomy software
• ARCO rotator port to directly connect the ARCO without the need for additional data or power cables
• DARK mode with dimmable LED lights, that can even be turned off completely
• GHOST mode to remove USB cable when used with EAGLE computer
• Temperature sensor port to automatically compensate focus caused by environmental temperature change
• Developed and manufactured in Italy
• Weight: 370 gr. (0.8 lbs)

Compact, lightweight and all-in-one design

SESTO SENSO 3 features a compact and lightweight enclosure that houses all control electronics, with ports conveniently located on the side. The unit includes dimmable status LEDs, which can be turned off completely to minimize stray light during nighttime observing or imaging sessions. Connectivity is streamlined and efficient: a USB-C port allows connection to an EAGLE or any Windows® computer using the included USB cable; the dedicated ARCO port enables both power and control of an optional ARCO camera rotator through a single cable; the 12V power port (5.5/2.5mm, center-positive) supplies power to both the motor and internal electronics using the included cigarette lighter-style cable (or by using an optional cable for direct connection to the EAGLE); and a temperature sensor port lets you connect the optional probe for use with third-party software that supports automatic focus compensation based on ambient temperature changes.

Easy installation with Self Centering Clamp 2 (SCC2)

SESTO SENSO 3 uses the new Self Centering Clamp 2 (SCC2), an evolution of the original SCC system, to easily connect the motor to the shaft of most focusers without the need for external brackets. SCC2 now supports multiple shaft diameters (25mm, 26mm, 33mm, 37mm) allowing for faster installation, and improved mechanical coupling with a wider range of focusers, without the need for other adapters. In fact now SESTO SENSO 3 connects directly to 37mm shafts and, by adding one of the included adapters, can be connected also to 25mm, 26mm, and 33mm diameter shafts. Another advantage of the SCC2 technology is that you can always use the manual (coarse) knobs of your focuser, even if SESTO SENSO 3 is installed, and thanks to the integrated encoder you won’t lose motor position if SESTO SENSO 3 is active. SESTO SENSO 3 is compatible with many telescopes (included bushings: red for 2,5mm diameter, black for 2,8mm diameter, blue for 2,4mm diameter, green for 3,5mm diameter, silver for 3,1mm diameter, gold for 4mm diameter), like (but not limited to these):

SkyWatcher EVOSTAR, EVOLUX and ESPRIT
SkyWatcher Newton and Quattro
Takahashi FSQ85 and FSQ106 with fine focus knob
Baader SteelTrack® focusers
FeatherTouch focusers
GSO Ritchey-Chretien with 2" and 3" focusers
Explore Scientific focusers

Integrated encoder: precise control with freedom of movement

SESTO SENSO 3 integrates a position encoder that tracks the movement of the focuser shaft with extreme accuracy. This allows the user to manually move the focuser, with SESTO SENSO 3 installed and powered on, using the focuser’s original knob without losing motor position. Perfect for users who switch between visual and imaging sessions, this also speeds up and improves the calibration process.

Another advanced feature is the Automatic Position Recovery function, which if enabled automatically restores the previous focus position if focuser movement is detected. This feature is particularly useful in public or educational observatories, where visitors or users may be tempted to manually turn the focuser knob or if the focuser is accidentally moved. Another useful application is when the focuser drawtube shifts under load (please note that SESTO SENSO 3’s encoder is able to detect only shaft movements, not internal focuser slips that cannot be corrected by just the focusing motor but depend on the focuser itself). If you enable this function, you can set a recovery delay (from 0 seconds for instant reaction up to 20 seconds) after which SESTO SENSO 3 automatically moves the focuser drawtube back to its previous position.

USB-C connectivity to control it from a computer

SESTO SENSO 3 features a modern USB-C port for direct connection to your control device, whether it’s a standard Windows 10 or 11 PC or the EAGLE computer. The USB-C interface offers a range of benefits over traditional USB connections: it’s reversible, making it easy to plug in even in low-light conditions, and it ensures a secure and reliable connection that’s resistant to accidental disconnections—especially useful in mobile or remote observatory setups. Plus, the wide compatibility with standard USB-C cables makes it easy to integrate SESTO SENSO 3 into any modern astrophotography workflow without the need for proprietary connectors.

Easy control with PLAY astrophotography software

SESTO SENSO 3 integrates perfectly with PLAY, the powerful astrophotography software developed by PrimaLuceLab to simplify and enhance your astrophotography. PLAY provides an intuitive interface that allows you to remotely control the focuser position with precision, directly from your EAGLE or standard Windows 10/11 computer. PLAY unlocks advanced capabilities such as AutoFocus, which automatically analyzes the stars dimensions and adjusts the focuser position for optimal focus position. In addition, PLAY includes features like temperature compensation, focus presets, and real-time status monitoring, making it the ideal solution astrophotographers. 

Advanced control with ASCOM drivers and third party softwares

Thanks to the provided ASCOM driver, SESTO SENSO 3 is fully compatible with a wide range of popular third-party astronomy software, giving you maximum flexibility in how you control your focuser. Whether you’re using applications like NINA, Sequence Generator Pro, MaxIm DL, or others, SESTO SENSO 3 integrates smoothly into your existing workflow. This level of compatibility makes SESTO SENSO 3 an ideal choice for advanced astrophotographers and observatories who demand both performance and software freedom. No matter which platform you prefer, you can count on SESTO SENSO 3 to deliver accurate results night after night.

WiFi connectivity to control it without the need of computer or physical hand pad

SESTO SENSO 3 features a built-in WiFi module that creates its own wireless network, allowing you to control the focuser from any smartphone or tablet—no cables or computer required! Simply connect your device to the SESTO SENSO 3’s WiFi network and launch the built-in Virtual HandPad. You’ll be able to move the focuser using your smartphone or tablet just like you would with a traditional hand controller. Thanks to convenient preset positions, you can easily save and return to specific focus points—perfect for visual observing as well. WiFi control remains active even when SESTO SENSO 3 is connected to a computer, allowing simultaneous control from two devices for added flexibility.

Full compatibility with ARCO rotator

SESTO SENSO 3 features a dedicated port for direct connection to ARCO, the robotic camera rotator and field de-rotator developed by PrimaLuceLab. With ARCO, you can remotely adjust the rotation angle of your camera to achieve perfect framing of your target. If you’re using an alt-azimuth mount, ARCO also allows you to de-rotate the field during long exposures—eliminating the need for an equatorial wedge. SESTO SENSO 3 and ARCO are designed to work seamlessly together, requiring only a single short cable for both power and data. No additional controllers or connections are needed, making it easy to build a compact, fully integrated, and automated imaging system for advanced astrophotography or scientific applications.

DARK mode with dimmable LED indicators

SESTO SENSO 3 is equipped with LED indicators on its body that provide useful visual feedback for device status and diagnostics. The LEDs are fully dimmable, and by enabling DARK mode—via PLAY software or the ASCOM driver—you can turn them off completely to preserve your night vision and eliminate stray light during astrophotography sessions. When using SESTO SENSO 3 with an EAGLE control unit, DARK mode activation can be automated in PLAY: as soon as an imaging sequence starts, all LED lights are automatically switched off, allowing for fully unattended and light-safe operation.

GHOST mode support and firmware updates

When used with an EAGLE control unit, SESTO SENSO 3 supports GHOST mode, allowing complete operation without needing a USB cable, for a cleaner setup. GHOST mode also acts as a backup communication channel: if the USB cable stops working, you can still access SESTO SENSO 3 through the EAGLE and continue your imaging session without interruption. In addition, firmware updates can be easily installed via PLAY software, ensuring your focuser always benefits from the latest features, improvements, and compatibility enhancements.

Temperature sensor port for optional external probe

SESTO SENSO 3 supports temperature compensation when used with the optional external temperature probe, allowing calculation of how the focus position shifts as ambient temperature changes throughout the night. Once the probe is connected, you can perform a temperature calibration directly in PLAY to determine the correlation between temperature and focus shift. After calibration, temperature compensation can be applied automatically by PLAY or by third-party software via the ASCOM driver, ensuring stable focus during long imaging sessions—even with very fast focal ratio telescopes (for example faster than f3) and in fluctuating environmental conditions.

SESTO SENSO 3: dimensions and weight

SESTO SENSO 3 includes all these advanced features in a lightweight, compact all-in-one chassis designed to be installed on your focuser without the need of external brackets. SESTO SENSO 3 weights just 370 gr. (0.8 lbs). See image below for product dimensions.