M83

AstroViking (Steve) · #1 07-05-2024, 09:37 PM

Evening all,

Continuing on with my saga (tragic tale, perhaps?) of the Megalens, I seem to have the focus sorted out after some reviewing of Ekos' settings. I'm still not super-happy with it, but this image is a lot better than my 'first light' image.

This time, I remembered to turn the guiding on.

Looking at the finished image, the focus looks a bit soft, which is probably an issue with the lens - optics have come a very long way since this thing was made.

The stacked image wasn't too bad, although I'd really love to get out to a dark sky and see how this lens performs, as the signal was pretty well swamped under all the light pollution. I suspect that more imaging time under darker skies would really bring out the colour in the galaxy - this one is rather beige...

I followed my usual stacking and processing workflow in Siril. I did try the 'Star Resynthesis' option in the 'Star Processing' menu after I had separated the stars from the galaxy/background. This option is brilliant - the odd-shaped stars are changed to completely round. I have no idea how this works, but I'll definitely remember to use it when I have odd-shaped stars again. The only issue is that further processing of the star layer requires a gentle hand, as several of the larger stars had a visible 'box' around them if I stretched the layer too much, or pushed too hard with the brightness / contrast in Affinity.

Image details:

* Gain: 100
* Offset: 10
* Temperature: 0 degrees C
* Exposure: 30 seconds
* Frames: 240 Lights, 50 Darks (2 hours integration in total)
* Filter: UV/IR Cut
* Stacked and pre-proc'd in SiriL, finished in Affinity Photo

Equipment:
Megalens @ 1000mm / HEQ5-Pro / ASI183MC-Pro / SV165+SV305 / Kstars/Ekos

As always, criticism / comments / feedback very much appreciated.

Cheers,
V.

Vapour38 (Lachlan) · #2 08-05-2024, 12:58 AM

Great work Steve, big fan of the natural colours coming out of the core. You’d be right in saying darker skies will bring out more colour and dust lanes, but I think you’d be surprised with the colours can you get now by playing around with curves - most galaxies are naturally beige.

You mentioned the stars were a bit bloated, but i think the colours have come out great, and playing around with their saturation might bring out more yellows and reds - if that’s your taste of course. Looking forward to seeing more!

xelasnave · #3 08-05-2024, 06:53 AM

Thanks Steve for posting your image and interesting cometary.

It is always a great pleasure to wake up and look to find something interesting here.

I think you have produced a great image and my only advice is to enjoy your achiements with not too much emphasis on what you wish to improve.

alex

Bodon (Steve) · #4 08-05-2024, 08:05 AM

Steve
Nice detailed photo mate

AstroViking (Steve) · #5 08-05-2024, 05:09 PM

Thanks everyone!

AstroViking (Steve) · #6 30-05-2024, 06:56 PM

Hi all,

I captured another 4 hours worth of data on M83 the other night. I was surprised to get any sort of image out of the muck, as my individual subs showed almost no data rising above the light pollution - and this was with 30 second exposure times...

So I'm up to 6 hours with the Megalens on M83, and I think it's time to try a different target.

On the plus side, I was really happy with my guiding - consistently under 1 arc-second RMS for the entire night. (Alex keeps saying we need to find all the good things. The guiding made me happy, as did the perfectly executed meridian flip operation.)

Processed identically to my previous M83 image - stacked in Siril (via the Sirilic front-end), split with starnet++, star re-rounding via Siril's inbuilt magic function, layers recombined and worked on with Affinity Photo

As always, comments and constructive advice appreciated.

Image details:

* Gain: 100
* Offset: 10
* Temperature: 0 degrees C
* Exposure: 30 seconds
* Frames: 720 Lights, 50 Darks (6 hours integration in total)
* Filter: UV/IR Cut
* Stacked and pre-proc'd in SiriL, finished in Affinity Photo

Equipment:
Megalens @ 1000mm / HEQ5-Pro / ASI183MC-Pro / SV165+SV305 / Kstars/Ekos

Cheers,
V

Cyberman (Rob) · #7 30-05-2024, 08:34 PM

Good one Steve. The more data the better SNR. With my modded DSLR I find not much improvement until about 2.5 to 3 hours then SNR improves greatly. I see you use afinity photo. Is that similar to GIMP that I use? Cheers,Rob

AstroViking (Steve) · #8 31-05-2024, 08:17 AM

Hi Rob,

Thanks!

You're definitely right about the additional data - especially from a light-polluted location. The hard part is sifting the data from all the noise and muck...

I can (usually) get good images with my normal rig, and I'm testing the Megalens to see how it performs for astro work. It's an f10, so really "slow" and has terrible vignetting. However, the longer reach makes up for that - or so I'm telling myself...

I've described Affinity Photo as a PhotoShop "clone" but at a much better price point and with all the features you'll ever need in an image editing program. It also has some astrophotography features built in and James Ritson has developed a library of macros specifically for astro processing.

I haven't touched GIMP, so am not in a position to offer a detailed comparison between that and Affinity.

Cheers,
V.

carlstronomy (Carl) · #9 31-05-2024, 10:51 PM

Steve,

Looking really nice indeed, you should be happy with this one. It is a target that really processes well as you add more data.
The extra hours were worth the work mate

Carl

AstroViking (Steve) · #10 Yesterday, 03:15 PM

Hi all,

I watched Cuiv's latest video last night about processing with free software - Graxpert, Siril and GIMP.

I've never used Graxpert before so thought this a good chance to try it out. I'm impressed with how well it dealt with the uneven gradient and then de-noised the stacked image.

I'm undecided about the colour change - my previous non-Graxpert image has a distinct blue/grey tinge to the galaxy's arms, whilst the Graxpert processed file has gone back to the beige palette.

I'll keep Graxpert in my tool kit and test further with different images and see how it all turns out.

The image below used the same stacked image as the previous one and aside from the Graxpert background extraction and noise reduction was processed in exactly the same manner. (Siril, starnet++, Affinity Photo.)

Oh, if you're using a macOS device with an Intel CPU then the Graxpert De-Noise AI routines version 3.0.0 and 3.0.1 do NOT work. They crash out with an error. The AI De-Noise routine v2.0.0 works fine.

Cheers,
V.

carlstronomy (Carl) · #11 Yesterday, 03:37 PM

I agree with you on the colour pallet change. You managed to get more out of the image but the stars went a little fuzzy. Maybe this technique with more data would work. I know I pulled over 6 hours of data on this target but it was with a Canon 450D.

There are so many imaging programs out there it is out of control. There seems to be so many more different tutorials using all the different software. I have tried a few and gone back to PS with a few simple plugins to make life easier.

What I have learned is data is everything, take enough and you will get a nice image no mater what software you use.

Carl