M31 and M42

[jacko61]

We had a remarkably clear night up here on the 16th Jan so I was out and imaging from fairly early on.  First was m31. 50 x 90 second subs taken through my Zenithstar 73 with 1:1 flattener.  ASI2600mc pro and Skywatcher EQ8r pro.  Guiding with a WO 50mm uniguide and asi290mm mini using PHD2. I've recently changed the uniguide rotolock for a ZWO Helical focuser which has made getting nice sharp stars in PHD2 so much easier so guiding never went above 0.3 total rms error. Processed in Startools with a bit of star reduction courtesy of STARNET++ and GIMP. 

The second image is my latest attempt at M42 and the running man. This is about 3 hours worth of 120 second subs using the same kit as above. This is my second go at processing the data - I tried to do some star reduction (as with M31) but wasn't at all satisfied with the result so this version is pretty much how it came out of Startools; I'm very impressed with the HDR module in startools - it's tamed the trapezium area very well without compromising the rest of the image.

Graeme

   

[ollypenrice]

I like the M31 with its dramatic and atmospheric colour.

I think the HDR routine has worked only moderately well on the Trapezium. There's some control of the brightness but the colour has been burned to white. Bleached out colour is common when the signal is very high. The real solution is to shoot a few short subs for the Trap. Because it's so bright you don't need many in order to have a good SNR. When I blend long and short subs in Photoshop I invariably have to boost the saturation of the short, bright ones to draw the colour inwards.

Olly

[jacko61]

Thanks for the tips Olly. I'll have to figure out how to blend more convincingly in GIMP as I don't have photoshop. I'm sure it should be possible but at the minute all I've got to grips with is adding a star layer over the results from STARNET++ and I'm not finding the results very convincing. This is an earlier attempt on the Rosette and I hate the look of the stars - they're more like paint spatters on top of the image than nice points of starlight. Obviously I still have some way to go  

Graeme

[AstroMuni]

On 06/02/2023 at 15:34, jacko61 said:

This is an earlier attempt on the Rosette and I hate the look of the stars - they're more like paint spatters on top of the image than nice points of starlight. Obviously I still have some way to go

I like the bright colouring it makes the nebula pop out giving a 3d look. I can see what you mean about the stars which look a bit like flattened minus signs on my screen. Are you using a Flatner - Could be due to distance not being perfect?

Edited February 7, 2023 by AstroMuni

[jacko61]

17 minutes ago, AstroMuni said:

I like the bright colouring it makes the nebula pop out giving a 3d look. I can see what you mean about the stars which look a bit like flattened minus signs on my screen. Are you using a Flatner - Could be due to distance not being perfect?

Yep, I have a tilt issue that's a well known problem with the ZS73 focuser drooping with the weight of the flattener and AS2600MC.  I'm not too bothered about star elongation in the corners, it's more the fact that they just don't look real, especially the main stars in NGC2244 at the centre of the nebula. Sterrenland got exactly the results I'm after in his rosette - 

 

[AstroMuni]

15 hours ago, jacko61 said:

Sterrenland got exactly the results I'm after in his rosette - 

Aww...in his post Sterrenland mentions how he has sharpened his stars. Have you tried that technique?

[Zummerzet_Leveller]

On 06/02/2023 at 15:34, jacko61 said:

I'll have to figure out how to blend more convincingly in GIMP as I don't have photoshop. I'm sure it should be possible but at the minute all I've got to grips with is adding a star layer over the results from STARNET++ and I'm not finding the results very convincing.

 

Hi Graeme.  I'm GIMP user and so far the only way I've found to make it work well is to create your stars layer from a much milder stretch so the stars don't bloat.  I then do a 2nd image heavier stretch and star removal on your base image for the background and bring the two together.  I use Siril and run an Arcsinh stretch for the star layer to get some colour but minimise the bloat etc.  When I merge the layers I use Screen or Addition (both work well but give slightly different results.  The downside of this process is that you may need to clean up the background layer a bit depending on the success of the star removal process.

[jacko61]

6 hours ago, AstroMuni said:

Aww...in his post Sterrenland mentions how he has sharpened his stars. Have you tried that technique?

No. He's using Pixinsight which I can't afford.  I have Startools, Starnet ++ and GIMP  When I get some time I think I'll download SIRIL and see what I can achieve with that.

Graeme