[DavidTrap (David)]

Thanks for the rapid fire comments everyone!

I'm pretty stoked with the detail. I've been watching Marc & Greg (plus others) do some amazing shots with their larger chips and Pentax lenses, but have had to wait 9 months for this focuser to arrive so I could try my combination. They're made by a guy in America as a sideline business. I ordered it in November and there were "many delays". It seems to work quite well and plugs directly into my AP computer which means I can control the focuser from Maxim via ASCOM. It's a servo motor rather than a stepper, so it doesn't plug into a Robofocus controller. The main reason I tried this combination was the mounting bracket and belts that he sold with the focuser - all up it was a reasonable package deal.

I didn't have any autofocus programmed, so focusing was done with a bahtinov mask for the 4 inch Tak balanced atop the lens (fortunately the target had just transited the meridian so the front of the lens was flat!) The diffraction spikes it produced were faint, but seem to have delivered the goods! It was only focused once at the start of almost 4hrs of imaging. I did have a dew strip around a metal lens hood (thanks eBay - <$10), so this may have helped keep the lens temp constant on what turned out to be a -5 degree night in Tropical Queensland!

Here is a photo of the rig - the Tak serves as the guidescope. To achieve focus with the camera lens on the QSI, I have to change faceplates which means I lose off-axis guiding. You can't see the focuser - it's on the other side of the CCD/Lens setup.

DT