To install the Gx USB or Gx ETH driver for TheSkyX, just download and run the installation package 'X2CameraGxUSB_Setup.exe' or 'X2CameraGxETH_Setup.exe' from the download section of this web site. Setup program installs driver DLL files es well as description files so TheSkyX recognizes them and offers them to the user.

Setup also installs “Microsoft Visual C++ 2008 SP1 Redistributable Package”, used by the driver. If this package is already installed on the target PC (which is quite likely, because this package is used by numerous other programs), it is not installed and the already present version will be used.

TheSkyX then allows choosing of the Moravian Instruments Gx ETH camera in the Imaging System Setup window:

Clicking the 'Settings...' option in the 'Imaging System Setup' window opens driver specific configuration window.

Adapter IP address box is available on the Gx Ethernet driver only. It allows entering of the Gx Camera Ethernet Adapter IP address (because the device works as a server, fixed address must be assigned to it, see the device documentation for further reference). It is also possible to enter FQDN if the device has assigned name in the Domain Name System. Up to four Gx cameras of any type can be connected to the Gx Camera Ethernet Adapter. Scan cameras button asks the device for a list of all connected cameras, which are then offered in the Select Gx ETH camera combo-box. It is necessary to scan for cameras when the IP address was changed.

The Select Gx USB camera combo box always offers all cameras currently connected to the host PC (note the USB is Plug-and-Play connection).

This configuration window adopts itself (enables/disables specific settings) according to the selected camera type. Beside choosing of the particular connected camera, the configuration dialog box allows definition of other parameters.

Camera read mode allows choosing desired read mode. Gx imaging cameras offer one slower mode with lower read noise (marked “Low noise”) and one faster mode (marked “Preview”). Guiding cameras offer “Slow read” and “Fast read” modes.

Preflash time defines time in seconds, for which the CCD is illuminated with near-IR LEDs to eliminate Residual Bulk Image (RBI), accumulated during previous exposure (more precisely not to eliminate RBI, but to make it uniform and reproducible regardless of the illumination of the scene previously imaged). If the LED preflash is not desired, this parameter must be set to zero.

Num. clears parameter defines the number of commands performed to purge the charge accumulated during preflash. If no preflash is performed (preflash time equals zero), default single clear is performed regardless of the value of this parameter.

Max. step defines the speed of temperature changes in degrees Celsius per minute. Ramped temperature changes (as opposed to rapid cooling/heating, often with temperature overshot on both sides) protects the CCD from shocks and ensures its longer life.

CCD chamber window heating allows increasing of heating of the CCD chamber front window, which limits condensation on the window front surface. Gx cameras already implement some level of chamber window heating to suppress fogging. Increasing of heating power can slightly limit the cooling efficiency on the one side, but on the other side it can prevent condensation in front of the CCD, which ruins images.

Camera fan on allows controlling of the camera fan. It is desired to keep the fan on in most cases because it very significantly reduces the detector temperature by keeping it close to ambient. This also reduces the CCD dark current (thermal noise pattern). Dark current doubles with every approx. 6 ºC, so lowering the temperature by 12 ºC causes 4-times lower dark current.

Gx USB/ETH Camera Filter Wheel in TheSkyX

Each G2 and G3 camera can be equipped with internal filter wheel. All G2, G3 and G4 cameras also support external filter wheels with larger number of filter positions, which operate the same way like internal wheels (they are indistinguishable from internal filter wheels from the software point of view). Such external filter wheel is the only option for the large detector G4 cameras, their filter wheel is too big to fit inside the camera head.

Filter can be also chosen from the Imaging System Setup window:

Because there is no way how to determine the actual filters in the filter wheel automatically, the camera driver reads the 'X2GxUSB.ini' or 'X2GxETH.ini' file (located in 'C:\Program Files\Software Bisque\TheSkyX Professional Edition\Resources\Common\PlugIns\CameraPlugIns' directory, where the driver DLL is also located) to determine actual configuration of filters, which will be then reported to TheSkyX. This file is ordinary text file following the .INI files conventions.

If multiple cameras handled by the same driver are used, it is possible to include camera ID into the file name, e.g. 'X2GxUSB.2158.ini' will be used for camera ID=2158 only (note leading zeros are not allowed in the ID). Driver searches for the ID-specific file name first and only if it is not found, it tries to open generic ini file name.

Example of the configuration file:

[filters]
Luminance, Gray, 660
Red, LRed, 660
Green, LGreen, 660
Blue, LBlue, 660
Clear, 0, 0

Filters are described in the [filters] Section. Every line in this section describes one filter position. Filter description is a comma-separated list of three values:

• Filter name: This name is returned to the client application, which can use it to list available filters in the filter wheel.

• Filter color: This color can be used by client application to display the filter name with a color, hinting the filter type. The color can be expressed by a name (White, Red, LRed, etc.) or directly by number representing the particular color (0 represents black).

• Filter offset: Distance to move the focuser to refocus upon filter change. Plan-parallel glass shifts the actual focus position back for 1/3 of the glass thickness (exact value depends on the glass refraction index, but for almost all glasses 1/3 is very close to exact value). Refocusing is useful when changing filters of different thickness among exposures or when some exposures are performed through filters and other without filters at all.

Filter offsets can be defined in focuser dependent steps or in micrometers (μm). If the micrometers are used, it is necessary to inform driver by the MicrometerFilterOffsets parameter in the [driver] section of the ini file.

[driver]
MicrometerFilterOffsets = true

[filters]
Luminance, Gray, 660
...

Value of the MicrometerFilterOffsets parameter can be expressed as true or false, as well as 0 (for false) or 1 (for true).

Unfortunately the current X2 Camera API used by TheSkyX to communicate with camera and filter wheel drivers does not support passing of the filter offsets from the driver to TheSkyX. It is necessary to enter filter offsets manually in TheSkyX Filter Names Setup window.

Supported cameras

Drivers version 1.0 support following camera models, including possible internal filter wheels:

• G2-0402, G2-1600 and G2-3200 (revisions 3 and higher)

• G2-2000(C), G2-4000(C)

• G2-8300(C)

• G3-11000(C), G3-16000(C)

• G3-06300, G3-01000

• G4-09000, G4-16000

• G0-0300(C), G0-0301(C), G0-0800(C), G0-2000(C)

• G1-0300(C), G1-0301(C), G1-0800(C), G1-1200(C), G1-1400(C), G1-2000(C)

Supported external filter wheel models:

• EFW-2S-12, EFW-2S-10, EFW-2S-7

• EFW-3S-7

• EFW-4M-5, EFW-4M-7

• EWF-4L-7, EWF-4L-9

Further reference

For the documentation of Gx cameras, refer to the 'G0 and G1 CCD Camera Operating Manual', 'G2 CCD Camera Operating Manual' and 'G3 and G4 CCD Camera Operating Manual'. These manuals are supplied with each camera in the printed form and can be also downloaded as PDF file from the web site http://www.gxccd.com/.