Thursday, 28 May 2015

Some more night-sky time-lapses with ZWO ASI120MC camera

My ZWO ASI120MC astro-camera Quick Review shipped with a 2.1 mm 150-degree fish-eye lens, which is good for doing "almost-all-sky" video / time-lapse photography pointing straight up. It has the dynamic range needed to be able to shoot both day-time and night-time skies.

It will also take other standard CS-mount CCTV lenses. I bought a 6 mm - 15 mm zoom lens for $20 on eBay, which is good for wide-field shooting when the camera is mounted "piggy-back" onto my telescope, or mounted on a tripod.

Here are a few night-time time-lapse videos which I shot to give a sense of what it can do.

The first video is a time-lapse of the "All-sky" view looking straight up with the 2.1 mm fish-eye lens (150 degree horizontal FoV). The video was shot using 5-second frame exposures, set to default 50% Gain, for 210 seconds of actual elapsed time. (Video shot at 8:39 pm 27 May 2015 in Brisbane; showing a very over-exposed Moon in the top right, and the Southern Cross and Pointers in bottom-centre of view.) Note: This sequence looks quite dark when viewed in a "window" on this page, but you can see more detail if you go full-screen.

Next comes a time-lapse looking almost due south, again with the 2.1 mm lens, using 30-second exposures @ 50% Gain, for 400 seconds actual elapsed time. (Shot at 8:52 pm 27 May 2015 in Brisbane; over-exposed Moon in top right; centred on Southern Cross and Pointers.) You can see a lot more stars and nebulosity with the longer frame exposures - e.g. hints of Eta Carinae and the Running Chicken.

Finally, here is a time-lapse looking south with the 15 mm CCTV lens, using 30-second exposures @ 50% Gain, for 600 seconds actual elapsed time. (Shot at 9:23 pm 27 May 2015 in Brisbane; centred on Southern Cross and Pointers.) The background sky is very light with this sequence, so I would probably get better results if I tweak the exposure settings; and I'm not sure that I got the focus quite right. Still, the amount of detail and faintness of the resolved stars isn't bad.