Installation

Takes about 15 minutes. You need administrator rights on the PC once.

1. Camera settings (on the camera)

Firmware: fp L 3.00 or newer; fp 5.00 or newer (Sigma’s camera-control support).
Setup menu > USB Mode: Camera Control, set as the default. If the camera asks “select connection mode” each time it is plugged in, the PC won’t see it as a camera.
Battery charged, or a USB-C power source. The camera stays on while in use.

2. Use a USB 2.0 port

Plug the camera into a USB 2.0 port, a USB 2.0 hub, or through a USB 2.0 cable. USB 3 (SuperSpeed) ports do not work with the libusb-win32 driver used here: the camera is detected, but every transfer fails. USB 2.0 still downloads a 61 MP frame in about 2.5-6 s.

What counts is the speed the camera connects at, not just the socket: the fp and fp L have USB 3-capable sockets, so a USB 3 cable (USB-C to USB-C, or USB-A marked SS / 3.x) in a USB 3 socket (blue inside, or marked SS) connects at SuperSpeed and fails. Any of these gives a working USB 2.0 connection:

a socket without SS markings (black inside);
a USB 2.0 hub in between (recommended on the mount anyway);
a USB 2.0-only cable (no SS / 3.x markings).

The symptom: Windows shows the camera under libusb-win32 devices, but connecting fails with -5 ... could not clear halt. It can also seem to depend on the camera: a body that worked yesterday fails today in a different socket or with a different cable.

Fix the cable in place at the camera. The fp / fp L USB-C socket does not hold the plug firmly: if the camera or cable moves (slews, meridian flips, a cable dragging on the mount), the connection drops for a moment. The driver reconnects by itself, but the frame in progress is lost.

Clamp or tie the cable to the camera cage, the L-bracket or the dovetail, close to the plug, so the plug cannot flex and the cable’s weight does not hang on it. A short right-angle USB-C lead helps.
Leave some slack between the camera and the mount for slews.
Use a good cable of 4 m or less: 5 m is the USB 2.0 limit and proved unreliable in testing; a powered USB 2.0 hub on the mount is better than a long cable.
A cable that has been pulled or bent a lot can start failing under load (downloads stall after the first 8 MB). If that happens, replace it (Troubleshooting).

In testing, a clamped cable ran all night (274 frames) without a single drop. The same setup with the camera loose on the bench dropped whenever the camera was moved.

3. Install the libusb-win32 driver for the camera (Zadig), once per camera model

Windows binds the camera to its own MTP driver, which does not work for camera control (the camera keeps disconnecting). Replace it with libusb-win32:

Download Zadig from https://zadig.akeo.ie/ and run it (accept the admin prompt).
Connect the camera (on, USB mode Camera Control).
Zadig: Options > List All Devices (tick it).
Pick the camera in the drop-down and check the USB ID: | Camera | USB ID | |—|—| | SIGMA fp L | 1003 C442 | | SIGMA fp | 1003 C432 |
Set the target driver (right of the green arrow) to libusb-win32.
Click Replace Driver (or Install Driver) and wait for “installed successfully”.
Unplug and replug the camera.

Check: in Device Manager the camera now appears under libusb-win32 devices.

If you used the older ASCOM.DSLR-based fp L driver, this was already done for the fp L. A second fp of the same model needs no further Zadig step.

Undo (back to Windows’ MTP driver): Device Manager > the camera > Uninstall device > tick “Delete the driver software for this device” > replug.

4. Install the driver (Windows service)

Download the release zip from the project’s Releases page and extract it, for example to C:\Temp\SigmaFpAlpaca.
Open Terminal (Admin) (Win+X) in that folder and run:
```
powershell -ExecutionPolicy Bypass -File .\Install-SigmaFpAlpaca.ps1
```
Add -AllowRemote if NINA runs on a different computer.
It installs to C:\Program Files\SigmaFpAlpaca and registers the service “Sigma fp L Alpaca driver”, which starts with Windows, needs no login and restarts itself after a failure. It also puts a “Sigma fp L driver setup” shortcut on the desktop.
It ends with a green Installed. Service ‘SigmaFpAlpaca’ is running.

Settings and logs: C:\ProgramData\SigmaFpAlpaca (settings.json, logs\driver-YYYYMMDD.log).

Update: run the installer of the new release the same way (settings are kept). Uninstall: powershell -ExecutionPolicy Bypass -File .\Uninstall-SigmaFpAlpaca.ps1 (add -RemoveData to delete settings and logs too).

5. First connection

Open the setup page (desktop shortcut, or http://127.0.0.1:11111/setup).
Connect from NINA or SharpCap (see Using with NINA and SharpCap).
On first connect the body is registered by serial number as Colour. For a mono-converted body, set it to Monochrome on the setup page.
Take one frame: the driver learns the body’s exact raw size. Reconnect once in the client.

Only one camera at a time should be connected to the PC.

6. Optional: Mass Storage mode for 60-300 s exposures

Under USB control the camera offers 1/8000-30 s and a fixed 300 s bulb. For any length from 1 s to 300 s (60, 120, 180 s …) you need a Yepkit YKUSH XS (switchable USB port; install its ykushcmd tool, no driver needed) and an LCUS-1 relay on the camera’s remote jack. Hardware, wiring, camera and driver settings, and the start/stop sequence: Mass Storage mode.