This was the first run with the camera lens adapter for my QSI583. I used a 20yo Nikon 85mm F1.8 lens at F4 - hence the 18-point stars. I also used a new belt drive focuser. I'll post some photos of the rig in due course.
I was quite impressed at Maxim being able to plate solve these widefield images and collected this data using an automated run in CCDC. The are 50mins of data for each LRGB filters - all 5 minute subs. L was taken a bin 1x1, while RGB were bin 2x2. Taken out at Leyburn during August's new moon - thanks to Ray & Steve for suggestions on composition!
Need to do some more research on processing widefields in PI.
I have found that many IIS viewers will only look at the attached thread thumbnail if it is provided, rather than bother with the large size link...no idea why, I suspect a bit of lazyness and simple hasty care factor
What an absolute STUNNER David. The colours and tightness of the stars are just fantastic for a lens image. Agreed the big image is a must see. Incredible detail.
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
Last edited by DavidTrap; 29-08-2012 at 10:51 PM.
Reason: added a bit
Absolutely no idea what the lens would cost now. Dad bought it in 1992 - probably ~$500 then!! His SLR days are behind him, so I've acquired the useful lenses. He always loved wide aperture prime lenses, so I'm fortunate to have an 85mm f1.8 and 50mm f1.4 at my disposal!
Seems fitting it uses cold room panels? I thought minus 2.7 in June was pretty cool with a fine dusting of icing sugar frost over everything at 3am. Minus 5 is getting towards "Man from Snowy River" territory.
Thanks Marc - I've been watching your work for a while...
Ta Geoff - I wonder if the slightly smaller chip 8300 CCD chip vs a DSLR chip means I'm working from the centre of a lens' illuminated circle and hence less affected by curvature?
