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My first attempt at M51 which was acquired during Feb/March. Considering the field of view,  I was quite impressed with the amount of detail in the image, so I decided to heavily crop the image for display purposes. I also decided to process the star layer separately from the galaxy which helped keep the stars relatively small. I quite like the overall result.

Alan

LIGHTS: L:11; R:10; G:9: B:8 at 600s and Ha: 3 x 1200s. BIAS: 100; DARKS: 30; FLATS: 40

M51.jpg.ed02069fafeca6a92776f6cfa0da6717

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Thanks for your comments.

On the "colours" points raised:  I've found calibrating my RGB stacked image with eXcalibrator (a freeware program) gives good results if your interested in obtaining an image with a good colour balance. Apparently, it is supposed to be more accurate than simply measuring a sun like "G2V" star.  I then follow this up with an application of Gradient Xterminator with the colour balance option checked.  The above image incorporates the Ha data via red channel blending in PS via the screen blending mode. 

Alan 

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25 minutes ago, alan4908 said:

Thanks for your comments.

On the "colours" points raised:  I've found calibrating my RGB stacked image with eXcalibrator (a freeware program) gives good results if your interested in obtaining an image with a good colour balance. Apparently, it is supposed to be more accurate than simply measuring a sun like "G2V" star.  I then follow this up with an application of Gradient Xterminator with the colour balance option checked.  The above image incorporates the Ha data via red channel blending in PS via the screen blending mode. 

Alan 

Your so polite to point my spelling mistake out the color does look  weird and very strange to me I have seen  many images and taken many images of m51 and I have never seen one look this  color  if  you do not like to be criticised on images I will not post any more comments on your work 

pat 

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10 hours ago, pyrasanth said:

I like this image but I wonder what the natural colours are like. I would love to be in a space craft really close to M51!

I would imagine not as day glow looking as this or other Hubble pallete images 

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I have seen plenty of renditions which find the colour to be like this. It isn't remotely unusual. The one I did with Yves was pretty much the same, though we used Ha in red in blend mode lighten.

https://ollypenrice.smugmug.com/Other/Best-of-Les-Granges/i-Sc3kgzc/A

Adam Block at the Mount Lemmon Observatory has a similar result. http://www.caelumobservatory.com/gallery/m51.shtml

... as does R Jay GaBany. http://www.cosmotography.com/images/small_ngc5194.html and Robert Gendler here: http://www.robgendlerastropics.com/M51NM.html

All of this is in good agreement with the astrophysics. The smaller galaxy and the core of M51 are composed of older, evolved stars which are redder. The hot blue stars lie in the spiral arms. There are threads of Ha rich gas and dust tracing the spirals.

We can disagree over the precise tones of red and blue and the degree of colour saturation but, grosso modo, the OP has found an entirely mainstream colour balance here. I suspect that using Ha in Screen has caused the Ha to drift more widely across the spiral, slightly affecting the blues, but not by much.

I'm impressed and feel that the galaxy might stand a little sharpening but the background, the stars and any faint stuff, would need to be excluded.

Olly

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Olly

Thanks for the comments  :happy11: 

The links contain amazing images of M51 !  As you suggest, I'll take a look at using the lighten as the PS blending mode instead of screen, I'll also try to do a bit more sharpening near to the core. 

Alan

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