ZWO ASI1600MM-cool – first light

It has been a very long while since the ASI1600MM-cool camera arrived with me. Its arrival however has coincided with cloudy skies or rainy nights, which when coupled with the longer days and shorter nights, meant that it has been nearly impossible to do any testing of deep sky imaging with this camera. But on Friday night, the sky became very clear with no clouds overhead. Hence I took out my portable setup to try imaging with this camera.Equipment used:

iOptron ZEQ25GT mount, ZWO ASI1600MM-cool camera (Gain 200 2min subs at -25 degrees C), Samyang 135mm F2.0 lens with Geoptik EOS-T2 adapter, Astronomik 12nm H-alpha filter, Nebulosity 4.1.

I have to say that initially I did have trouble with this camera and Nebulosity such that it would not save any images (and timed out after 30 seconds). But updating to the latest ZWO drivers (v1.3.5.20) available from their website, and updating Nebulosity to the latest version 4.1 has solved this problem – all my image files from Friday night were saved just fine.

In total I took 20 H-alpha images at Gain 200 2min subs which seems to be the right setting without clipping the shadows or highlights; using Gain 300 2min subs results in some clipping in the highlight area. For comparison my ASI178MM-cool camera requires me to use Gain 200 3min subs to achieve the same results. So I have gained about 1/2 stop of exposure, which will be very useful.

In order to generate the calibration files, I also took 100 x flats, 100 x bias and 15 x dark frames at Gain 200. Unfortunately I am unable to upload the full sized images onto my website, as they are too large. But hopefully the images below will give you an idea of what they look like Рthey were stretched to be non-linear in Pixinsight.

I cannot see much fixed pattern noise in my master bias file.

Master bias frame Gain 200
Master bias frame Gain 200

The Master dark file certainly shows less amp glow at the corners than that of the ASI178MM-cool, which is great.

Master Dark frame Gain 200
Master Dark frame Gain 200

Now I used the Samyang 135mm F2.0 lens wide open coupled with the Astronomik 1.25″ H-alpha filter mounted into the Geoptik EOS-T2 adapter with the ASI1600MM-cool camera using its T2-T2 adapter. As you can see, although there is corner vignetting when the image is made non-linear, the 1.25″ filter does not result in completely black corners. So the smaller filters work just fine – great for me.

Master Flat frame - Samyang 135mm F2.0
Master Flat frame – Samyang 135mm F2.0

So I have managed to image the Heart and Soul nebulae together in H-alpha, and  processed them in Pixinsight. I did use Drizzle integration to produce an even more massive image, but have cropped away the edges to frame them better. So the ASI1600MM-cool should work great for other wide-field targets (such as the Elephant trunk, North American nebula etc) when coupled with the right camera lens.

Heart and Soul nebulae in H-alpha
Heart and Soul nebulae in H-alpha

So far I am pretty impressed with the ASI1600MM-cool. Unfortunately due to the time of year (very short nights) and where the Heart and Soul nebulae are situated in the sky at the moment (North-East by the time it gets dark in UK and obstructed by my house) I will not be able to image in the remainder of the narrowband channels (O-III and S-II) to produce a coloured image. But this is a start.