Wanderer Astro FETA M92 Focuser and Electronic Tilt Adjuster

A Dual-Role Focuser and Electronic Tilt Adjuster

The FETA M92 is engineered to solve two critical imaging problems: achieving perfect focus and eliminating sensor tilt. Instead of requiring separate components, it combines both functions into a single, compact device. This unified design simplifies your imaging train and puts both focus and tilt under software control.

Typical applications include the PlaneWave DR500, Takahashi TOA 150, Takahashi Epsilon 130/160/180, SkyRover 130 APO Pro, Takahashi FSQ130, William Optics RC16, AstroPhysics RH305, Askar 65PHQ and Takahashi FSQ106.

3 Independent Points Sharing 4 mm of Travel

The device operates via three independent adjustment points, labeled 1, 2, and 3 on the body. When all three points move together, the FETA M92 acts as a high-precision focuser. When moved independently, they correct for sensor tilt. This dual-functionality operates within a shared total travel range of 4 mm.

This shared travel is a critical design trade-off. The more tilt you introduce to correct your optical train, the less travel remains available for focusing. The WandererEmpire software clearly displays the available focus travel, allowing you to manage this balance and ensure you have enough range for your autofocus routines.

0.2 Micron Accuracy and USB-C Control

At the heart of the FETA M92 is a drive system delivering 236,467 steps per millimeter, resulting in an effective positioning accuracy of 0.2 microns. The WandererEmpire software accepts target positions in steps of 0.001 mm. Control is handled through a USB 2.0 Type-C port with screws, and the unit takes 12 V 1 A power through a DC5521 input (10 to 15 V allowed). The operating temperature range is -30 to 50 degrees Celsius.

A 15 mm Optical Path in a 20 mm Body

The FETA M92 is designed for modern, back-focus-critical imaging trains. While the total body thickness is 20 mm, the M92 mounting surfaces on each side are recessed by 2.5 mm. This means the actual back focus consumed between the two threaded connections is only 15 mm, preserving precious space for filter wheels and off-axis guiders. If you install both included adapters, the effective back focus becomes 20 mm.

One caveat from the manual: if the stop ring of your M92 male accessory is larger than 109 mm in outer diameter, it cannot sit in the recess, so add that 2.5 mm to your back focus calculation. Using Adapter 1 as an M85 female adapter and also screwing it down adds a further 5.5 mm.

M92 Threaded and M3 Bolted Connections

Both the telescope and camera sides feature identical connection interfaces, though they are clearly labeled and must be installed in the correct orientation for tilt adjustments to work as expected. The primary interface is an M92x1 female thread with a maximum allowable engagement of 7 mm; if your accessory has longer threads, you must use spacers. For custom adapters and direct mounting, each side also provides twelve M3 threaded holes with a 5 mm maximum screw engagement.

Included Adapters: M92 Male, M85 Male, and M85 Female Interfaces

The FETA M92 ships with two versatile adapters to ensure broad compatibility. Each adapter is 2.5 mm thick and sits in the recess of the FETA M92 body, and either one can go on either side.

• Adapter 1: Gives an M92 male thread when secured with the provided M3 screws, or an M85 female thread when its M92 male thread is screwed into the FETA M92 body.
• Adapter 2: Gives an M85 male thread. It is secured with the provided M3 screws, and you choose its rotation angle, which sets the final orientation of the device when the threaded connection is tightened.

Optional Adapters: System Integration for Takahashi and Moravian

For seamless integration with specific telescope and camera systems, Wanderer Astro offers a range of optional bolted adapters. The manual lists these adapters available at release:

• Bolted M68 Female Adapter for Wanderer FETA M92
• Bolted M72 Female Adapter for Wanderer FETA M92
• Wanderer FETA M92 Bolted Adapter for Moravian C3 M68 Adapter/OAG MKII
• Wanderer FETA M92 Bolted Adapter for Moravian C5 M85 Adapter/OAG MKII
• Wanderer Saddle Replacement Kit for Takahashi Epsilon E130
• Wanderer Saddle Replacement Kit for Takahashi Epsilon E160
• Wanderer FETA M92 Adapter Kits for Takahashi Epsilon 180
• Wanderer FETA M92 Adapter Kits for Takahashi FSQ106

8 kg Capacity and Absolute Zero Position

Engineered for professional imaging trains, the FETA M92 supports a payload of up to 8 kg, calculated with the center of gravity 100 mm from the FETA M92. Despite its strength, the body weighs only 750 g. A key feature for remote observatories is its fixed mechanical zero, which can be calibrated automatically. It gives the three points a fixed reference that the device can find again on its own, which is more reliable for unattended and remote operation. The fully enclosed structure prevents light leaks, and when stacked with a WandererRotator, the combined thickness is only about 35 mm.

The WandererEmpire Interface for up to 6 Devices

All control is managed through the WandererEmpire software for Windows. The interface shows the current status of the FETA M92 and gives direct control over each of the three adjustment points, with a Goto for a target in millimeters and a Zero button. You can connect up to 6 FETA M92 units from a single PC, choosing the COM port manually (Wanderer devices show a CH340 suffix in Device Manager) or letting the software search for it. Five named presets, such as "East" and "West", record the tilt values of the three points for different telescope orientations and recall them with one click.

ASCOM & NINA Drivers: Native Integration for Automated Imaging

Installing WandererEmpire also installs the necessary ASCOM driver and NINA plugin. In NINA, the device appears as "Wanderer FETA M92 (1)" through "(6)," corresponding to the device number in WandererEmpire. The plugin adds custom instructions to the NINA Advanced Sequencer, "Apply ETA Automatic Adjustment", "Apply ETA Preset" and "Connect Device". Note that the position value reported to ASCOM is divided by 10, so a position of 10,000 in WandererEmpire will appear as 1,000 in ASCOM-compliant software.

5 to 10 Micron Results with NINA Hocus Focus

The FETA M92 enables fully automatic tilt adjustment through its integration with NINA and the Hocus Focus plugin. After configuring WandererEmpire with your sensor size and the Hocus Focus save path, the software reads the Aberration Inspector results and calculates the necessary corrections. You run Aberration Inspector, let the FETA M92 adjust, then run it again to check, and repeat; a confidence of 90 percent or more is the target before each move. The Adj Microns values at all four corners can typically be brought within 5 to 10 microns. The focuser step size to enter for the FETA M92 is 0.04, without Reverse. It is important to note that this process corrects for sensor tilt only; it cannot fix poor telescope collimation.

Firmware Updates and an Open Serial Protocol

Firmware updates are handled directly within the WandererEmpire software; disconnect the FETA M92 in WandererEmpire before uploading, or the COM port cannot be opened. For users building custom control solutions, a serial protocol is available. This allows direct communication with the FETA M92 over a standard 19200 8N1 serial connection to command absolute moves, trigger zero detection, and receive status updates every 200 ms.

Wanderer FETA M92 vs. ETA M54: Zero Position

Wanderer Astro compares the FETA M92 with its Wanderer ETA M54 on one point: the FETA M92 has an absolute mechanical zero position with automatic zero detection, which makes it more reliable for unattended and remote operation. It also has an enhanced light-leak prevention design with a fully enclosed structure that blocks any direct light from entering the device.