First light image - ASI2600MM Pro

[The_bluester (Paul)]

Early this month my long awaited ASI2600MM arrived, and the sky duly cleared for that evening and the next (And not since) so it was a mad frenzy to get it set up and out for first light.

The target chosen was SH2-34, which is near M8 and is relatively strong in HA, has some Oiii and I don't know about Sii as my Sii filter only arrived last week (Fedex managed to take three weeks to deliver it within Australia, two of which were a little holiday in Ballarat, where it remained until I started making phone calls) I had made a start on this image with some HA data shot with the previous camera (The ASI2600MC) but decided to abandon that. All data in this image is from the 2600MM. This is 32 X 120 second R-G-B subs, 19 X Oiii 1200 second subs and 18 X 1200 second HA, all at zero gain and 50 offset with the camera cooled to -10. Integration of the various filters in Astro Pixel Processor and RGB combination and addition of the HA-Oiii in Photoshop, calibration by master flats from 25 flats each from the various filters and a master bias created from 100 bias frames. I am pretty happy with this for a first light and for my first proper mono image.

Astrobin link to high res. https://www.astrobin.com/full/oiilf5/B/

I have posted this before, but this Astrobin link is an animated gif comparison of the HA data shot with the mono camera versus the data shot with the OSC and debayered with the HA algorithm in Astro pixel processor. Moreal of the story is if you can afford it, don't calculate something you can measure, or in AP terms, don't interpolate what you can natively capture. https://www.astrobin.com/full/dsafar/0/?mod=&real=

[Andy01 (Andy)]

Well done.
A tad noisy at high res, but a very decent first light!

Nice find too

[The_bluester (Paul)]

Can't argue there, being my first crack with the mono cam I am inclined when I have a slack day, to redo the process from scratch, including some of the things you and I have discussed.

[gregbradley]

Lovely image Paul and a great first light. Noise is minimal but probably came from using Gain 0 for narrowband. For narrowband the usual strategy is to use high gain with its lowest read noise and longer subs like 600 seconds.

Its a pain because Sky X and I think other programs don't let you change gain etc mid an imaging run. So you have to stop once you've gotten your LRGB and change to high gain and do your narrowband.

When processing then you need a 2nd library of darks, bias for the narrowband. You may be able to reuse your flats but trial and error will confirm that as flats are about uneveness of illumination not noise.

Greg.

[The_bluester (Paul)]

Voyager is able to flip between gain settings at will. The noise seems mostly to be coming form the Oiii so I might (If I ever get a clear sky again) try shooting that on a higher gain, the starless HA looks quite smooth as does the RGB.

There has been a bit of discussion about it, but these cams seem to calibrate quite well with just a master bias, so there may be no need for me to shoot 1200 second darks at least initially (Though exposure time may be shorter on gain 100 anyway to avoid saturating anything) I should add that on these cameras gain 0 is unity gain (Or as close to unity as they go, all gain settings are above unity and 0 is just a bit above it) so it is not really low gain as might have been seen in the likes of my old ASI294 where gain 0 was about 4e/ADC

The Funny enough, the noise seems to be being accentuated by a noise reduction step. I was using Nik tools Define, but it seems to be introducing what looks a lot like sharpening worms! More investigation required.

[AdamJL]

That's a beauty. A really dense and packed field, so much to look at. It's shots like this that get the imagination working. Thanks for sharing

edit: looking at the image at high res, there's definitely some cool nebulosity in there, with some great cloud definition. A lot more integration time would bring some of that out nicely!

[gregbradley]

Originally Posted by The_bluester

Voyager is able to flip between gain settings at will. The noise seems mostly to be coming form the Oiii so I might (If I ever get a clear sky again) try shooting that on a higher gain, the starless HA looks quite smooth as does the RGB.

There has been a bit of discussion about it, but these cams seem to calibrate quite well with just a master bias, so there may be no need for me to shoot 1200 second darks at least initially (Though exposure time may be shorter on gain 100 anyway to avoid saturating anything) I should add that on these cameras gain 0 is unity gain (Or as close to unity as they go, all gain settings are above unity and 0 is just a bit above it) so it is not really low gain as might have been seen in the likes of my old ASI294 where gain 0 was about 4e/ADC

The Funny enough, the noise seems to be being accentuated by a noise reduction step. I was using Nik tools Define, but it seems to be introducing what looks a lot like sharpening worms! More investigation required.

I tend to only use contrast enhancement rather than sharpening which usually leads to a degrade and an unnaturalness.

I don't know what is used for narrowband on the ASI cameras which have different numbering systems for gain for some reason. But I am sure it would be easy to find on Cloudy Nights where this sort of thing is talked about a lot or on Astrobin images that you like using this camera.

Greg.

[The_bluester (Paul)]

A little hard to find much information on the 2600MM to date, there are not a whole lot of them in the wild yet. The read noise even at lowest gain is still quite low (Worst read noise is 3.3e so around half that of something like a KAF8300)

The Nik module I was using is supposed to be noise reduction only, but in this case it seemed to accentuate what looked like sharpening worms (Very little sharpening applied to begin with)

First image from the cam, I reckon I just need to practice with it more. My next test would be to half the NB exposure length from 1200 seconds to 600 and see how nicely the data stretches. Twice the subs of half the length might well smooth out the image nicely, time will tell.