M33, LRGB using ASI6200

[symmetal]

Here's my first processed image using the ASI6200 with my FLT98. I've binned it 2x2 in software as little real resolution is lost. It's a centre crop to just show the galaxy.

L = 3.9 Hrs total at gain 0, RG and B = 1.6 Hrs total each at gain 100 (3.2 x actual gain), and HCG mode. Sky brightness -21.34 using Unihedron.

Processed in Startools. Small final adjustmests in Photoshop. I also tried blending in some Ha to Red but it just made the red patches brighter without really adding much so I left it out. Click for full size. 🙂

Alan

 

 

[kirkster501]

Lovely, top drawer, with spectacular resolution, nice subtle colour and great stars. If I may say, I think you could stretch the HII regions a bit more and it would be even better.  A bit more, don't over do it.

Edited September 29, 2020 by kirkster501

[Xplode]

Great resolution as always with this camera!
When in your processing do you scale it down? I've found it's best to do after all other processing.
In my opinion your backgound is a little too dark, the value is around 20 for your image, a value of around 30 would look a lot better!

Background value in your image


After changing the background value

 

 

Before and after changing the background value, looks a lot better! (

[symmetal]

5 hours ago, kirkster501 said:

Lovely, top drawer, with spectacular resolution, nice subtle colour and great stars. If I may say, I think you could stretch the HII regions a bit more and it would be even better.  A bit more, don't over do it.

Thanks kirkster501, 🙂

Binning helped a lot with cleaning up the stars and making them look better. 😀

I find Startools keeps the background fairly dark during processing to emphasise structures and when it comes to adding the colour the default saturation looks too much so I dial it back. I do the final background lift in Photoshop which does desaturate the image overall. Perhaps I should leave the default saturation in Startools and see how it looks after Photoshop.

I tried adding the Ha as a 'lighten' layer to the red channel in photoshop and it just enlarged and brightened the already red patches and added some noise. I'll try again. I imagine you can denoise or blur the Ha layer quite a bit without it affecting the final result.

1 hour ago, Xplode said:

Great resolution as always with this camera!
When in your processing do you scale it down? I've found it's best to do after all other processing.
In my opinion your backgound is a little too dark, the value is around 20 for your image, a value of around 30 would look a lot better!

Thanks Xplode, 🙂

I was going to scale down in Photoshop at the end, but the full resolution image was quite slow in processing in some of the Startools modules. I like to process the full image and then crop the result in Photoshop. Startools suggested workflow order, says to 'bin' early in the processing steps, which certainly helped with processing time. It also shows more how the final result will look during each step. You can 'bin' to any resolution in Startools so it uses downsampling algorithms.

I lighten the image in Photoshop, as in Startools it's best to keep the background fairly low or it will tend to stretch the background noise. Olly and others suggest 23 as the background level and I tend to use around 20. I'll try it with a higher value. 🙂

Alan

[Xplode]

Olly has suggested 28-30 before so maybe his vision has changed 😂

In my opinion 20 is certainly too dark on a calibrated monitor. 

 

 

I might also mention that high gain is ok for luminance too, ive taken 60-300s exposureswith both slow and medium fast scopes. I haven't found a reason to use low gain on the asi6200 

Edited September 29, 2020 by Xplode

[symmetal]

41 minutes ago, Xplode said:

Olly has suggested 28-30 before so maybe his vision has changed 😂

In my opinion 20 is certainly too dark on a calibrated monitor. 

 

 

I might also mention that high gain is ok for luminance too, ive taken 60-300s exposureswith both slow and medium fast scopes. I haven't found a reason to use low gain on the asi6200 

I admit my monitor is not properly calibrated, just set so you can see the individual steps on a grey scale stepwedge.

Thanks for the info on the ASI6200 gain setting. I was going to do some tests to see the difference as the Zwo claims on dynamic range retention may have been exaggerated. I thought I'd do luminance on 0 gain as the exposures are relatively short anyway, but if it's not really noticeable in the results, I'll use gain 100 for L too. 😀

Alan

[alan potts]

Lovely image Alan, I don't think the back ground is too dark, lets face it, it is all down to personal taste saturation and background. I often feel people over egg the saturation then find myself doing the same thing. I use 30 myself but as I don't have any graduation tool the centre is always a tad lighter, I sometimes make a grad in PS but most of the time don't

Alan

[tomato]

Lovely M33, the Ha regions are not over saturated, with dust lane detail right to the core.👍

[MarkAR]

Super image right to the core.

[symmetal]

Thanks Alan, tomato & MarkAR. 😀

I believe the Astronomik Deep-Sky RGB filter set and L3 Luminance helped with avoiding coloured halos on the medium brightness stars which I tended to get with the lower cost Baader filters. I thought after spending that amount on the camera, it's worth splashing out  a bit more on the filters, and it's seemed to have paid off.

Startools HDR module is very good at revealing DSO core details. 🙂

The galaxy is enclosed in a bright oval which is largely independent of the spiral arm structures. Some images seem to deliberately suppress this oval and make it similar to the background level. Doing a simple stretch on the data does show that the bright oval is real and not a processing artifact. I suppose it's just dust and debris left over from the galaxy formation. Increasing the sky background level would help reduce the effect of the oval 'glow' if that's what you want to achieve I suppose. 🙂

Alan

[morimarty]

Thats a great Image of M33. Looks like You have got the combination of the Flt98 & Asi6200 in perfect harmony. Very well done.

[Red Chilli]

Wow this is amazing 

[Backyard Space Dude]

Wow! It’s so detailed, and the core is perfect!

[geoflewis]

I've only just seen this and it is superb...!!