David's Astronomy Pages (All Sky Camera) AllSky Tests with ZWO ASI178MC Colour Camera  2017-01-07 / 2017-01-08

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178MC 2017-01-07

AllSky Tests with ZWO ASI178MC camera

Notes

Pictures Videos Night Summary Plot

- AllSky tests with new ZWO ASI178MC camera and its 2.5mm accessory 'all sky' 170deg lens - Generally clear skies during 2.5 hour period around midnight, calm conditions with 0-3 mph windspeed,  4-5 degC, 90% RH, moon 75% phase - Images acquired using SharpCap 2.9 - Camera operating with temperature of 13-14 degC - The ZWO ASI178MC camera's prime use is for high resolution planetary imaging through 12" LX200 with other secondary uses for autoguiding and sky imaging through a 80mm f/6 refractor.    The camera will however also be useful for recording colour images of active aurora events, and for exploring the implications of using a colour CMOS camera with my AllSky software currently used to operate a b/w Oculus camera.  - The camera will however also be useful for recording colour images of active aurora events, and for exploring the implications of using a colour CMOS camera with my AllSky software currently used to operate a b/w Oculus camera.  With this current lens the camera would need to be tipped toward in a north direction to fully capture, E, N and W views down to the horizon to capture Aurora displays (limiting southern view in the process).  AllSky Lens modelling /calibration and Panoromic View Generation would need re-coding to enable a tipped camera view.

Pictures

AllSky View taken with ZWO ASI178MC colour camera (170 deg, 2.5mm lens) 30s exposure with medium gain, single frame Glare at bottom is from Moon lying just out of frame. North is on righthand side For AllSky use it would be preferrable if the lens produced a smaller image on the 7.4 x 5.0mm IMX178 chip in order to capture the view down to near the horizon at the top and bottom of the image The chip has plenty of pixels (3096 x 2080) to still preserve good resolution of the sky compared to the Oculus camera. It's not clear if the ZWO accessory lens could be moved to a position that could give a smaller image, but still be focussed at ~ infinity
CMOS Colour Image (25% size, 3096 x 2080 original) 30s exposure , gain 250, 1x1 binning, RGB24 2017-01-08  01:03hUT [Larger Image, 40% size] [ Full Size Image ] Larger & full size images show that stars are well focused on the left and centre of image, but are more poorly focussed or deformed on right hand side (lens quality issue?)
Equivalent view through with Oculus AllSky Camera (180 deg lens) Taken at same time as above image, site offset by 15m distance and 3m in height
B/W Image (50% size, 1392 x 1040 original) 30s exposure , gain 250, 1x1 binning, RGB24 2017-01-08  01:03hUT [ Larger image 75% size, showing Annotated Stars]
Examples of detail in AllSky View taken with ZWO ASI178MC colour camera
Orion		Plough
[ Original size ]		[ Original size ]
Polaris		Perseus & Cassiopeia
[ Original size ]		[ Original size ]
2.5mm, 170 deg FOV, 'all sky' lens supplied with the ZWO ASI178MC Camera
AllSky View taken with ZWO ASI178MC colour camera (170 deg, 2.5mm lens) Image produced in SharpCap using Live Stack facility Rotation of stars around North Celestial Pole is clearly demonstrated in this image which stacks 21 x 30s exposures (10.5 minutes total exposure).  The bright star at the centre of rotation is of course Polaris. Note:  Averaging of frames in Live Stack's stacking process reduces background noise but also reduces the intensity of trailed stars, with intensity dropping off as more and more frames are collected. Ideally like to have option to show max pixel value rather than average.
CMOS Colour Image (25% size, 3096 x 2080 original) 21 x 30s exposure, gain 250, 1x1 binning, RGB24 2017-01-08  01:03 to 01:13hUT [Larger Image, 40% size]
AllSky View taken with ZWO ASI178MC colour camera (170 deg, 2.5mm lens) Image produced live in SharpCap using Live Stack facility with Align Star option enabled Stacks 20 x 30s exposures, 10 minutes total exposure) Note:  With realtime alignment of stars (including image rotation), the intensity of stars is increased whilst background noise is reduced. Houses, trees, fences are necessarily blurred by the align and stack process. Possibly due to the fish-eye nature of the lens and lens ?quality issues on right hand side, stars are not as point like as one would like. However the potential of this technique for taking Deep Sky Images using a longer focal length lenses or telescopes is clear. Might be quite good for recording multiple meteors (though their brightness might be diminished by frame averaging) Ideally like to have option to show max pixel value rather than average.
CMOS Colour Image (25% size, 3096 x 2080 original) 20 x 30s exposure, gain 250, 1x1 binning, RGB24 2017-01-08  00:48 to 00:57hUT [Larger Image, 40% size]
Detailed view of Perseus, Cassiopeia and Andromeda region in above Image Image produced live in SharpCap using Live Stack facility with Align Star option enabled Stacks 20 x 30s exposures, 10 minutes total exposure) 2.5mm all-sky lens + ZWO ASI178MC on a tripod with no tracking
CMOS Colour Image (100% size of cropped region from 3096 x 2080 original) Image details as above
AllSky View taken with ZWO ASI178MC colour camera (170 deg, 2.5mm lens) 5s exposure with higher gain, single frame Note:  Noise levels are clearly higher in this 5s image, compared to the 30s images above.
CMOS Colour Image (40% size, 3096 x 2080 original) 5s exposure, gain 400, 1x1 binning, RGB24 2017-01-08  01:34hUT [Larger Image, 40% size]

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 Videos

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Night Summary Plot

Night Summary Plot - North Sky (2017-01-07 / 2017-01-08) Times on plot are local GMT times (= UT time)

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