Handbook for the SX Mini Filter Wheel - Issue 2, February 2019
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plate off the centre bearing and place it down with the magnet screws facing
upwards. Your threaded filters may now be screwed into the plate from the magnet
screw side, placing them in the desired numerical order according to the engraving
on the plate. Unmounted 36mm filters are fitted into the recesses in the top surface
and held in place with nylon screws and washers. Re-assemble the wheel by
reversing the sequence of operations above.
Installing the software:
No drivers are required for the SX mini Wheel. The USB input is an ‘HID’ device which
Windows recognises automatically. Popular third-party software, such as AstroArt
and MaximDL include the command sets for the SX mini Wheel, and the latest SX
software can also be used with the wheel. You may also use a simple Windows
‘Console’ program, which is provided on the USB Stick. This program, ‘SX Filter
Wheel.exe’, may be copied into a folder on your computer and will display a filter
wheel control panel when executed. It may be found useful for both testing the
wheel and operating it when the camera software does not support the SX wheel
protocols.
Connecting up the wheel:
USB control:
If you are using USB control, then the only connection required is that between the
USB port on the wheel and a USB output on your computer. You may, of course, use
a USB hub, if necessary – a powered hub is recommended to ensure that the wheel
motor has sufficient torque to operate reliably. When the wheel is first connected,
Windows will display a message about ‘New hardware found’ followed by ‘SX filter
wheel’. Shortly afterwards, the wheel will rotate once or twice as it calibrates and
determines the number of filter positions available. It is now in position 1 and ready
to use.
Using the OAG pick-off:
The OAG pick-off assembly is designed to be used with an SX Lodestar or Ultrastar
series of guide cameras, but other types may be employed if they have a 'C' mount
(1 inch) threaded input collar. Fit the guide camera onto the C mount ring and slide
the ring onto the OAG tube. Use the small lock screw to fix it about halfway down
the tube. Loosen the large lock screw and slide the prism tube until the prism is
roughly tangential with the edge of the filter aperture. With this assembly attached
to the 'scope and the main camera operating, focus the main camera to give a sharp
image. Now switch to the guide camera images and adjust the C mount ring along
the pick-off tube until the guide camera is focused on any visible stars in the guider
field. If you cannot see many stars, or they are badly distorted, slide the prism
assembly a little further in, but be careful not to 'shadow' the main camera field.
