M51

[Petergoodhew]

Messier 51, one of my favourite targets, imaged from Spain. My first HaLRGB image.

Ha 24x1200s

Lum 56x300s, 19x900s

Red 17x300s, Green 20x300s, Blue 20x300s

22h5min total integration

Comments, critiques, and suggestions welcome.

[swag72]

Here's a couple of thoughts that spring to mind.

I think it's too yellow at this point in time so you've lost the more natural star colour. Secondly, I think you've forced the tidal wave a little. It's got a VERY abrupt finish against a dark background which in my opinion looks very pushed and false. 

The data is all there for sure, which is great, so well done! Just a little bit of processing improvements to be made and I think you'll have a great image there  

Hope that helps and doesn't come across as a negative nancy

[celestron8g8]

Really good capture but what happened to the top section ? Sometimes if I have a building or something obstructing my view I have gotten images with sections missing .

[Petergoodhew]

2 minutes ago, swag72 said:

Hope that helps and doesn't come across as a negative nancy

Your comments always help Sara.  Many thanks.  Constantly looking to learn from those with more experience!

[MarsG76]

I agree with above that it is a bit too yellow and the glow has a abrupt stop and needs to be softened or feathered out into the blackness of space.

With that much HAlpha data, you should be able to bring out a lot more nebulosity within the galaxy, but that might come through once you color balance the data by adding a bit more blue in the white levels.

Otherwise you have plenty of data, detail and its a great image.

 

[Petergoodhew]

Thanks everyone for the feedback.  I've done some homework based on your comments and come up with this.

[MikeODay]

Wonderful image Peter.

[Petergoodhew]

12 minutes ago, mike005 said:

Wonderful image Peter.

Thanks Mike. I'm a slow learner, but gradually making progress.  Here is my first attempt at M51 and there's quite a difference:

 

[MikeODay]

29 minutes ago, Petergoodhew said:

Thanks Mike. I'm a slow learner, but gradually making progress.  Here is my first attempt at M51 and there's quite a difference:

 

 

Looks like pretty good progress to me  

[Rodd]

Allot of data there. IMO your galaxy is very bright and if you bring down the histogram just a bit (trial and error--but not allot), you'll have more contrast in the galaxy (the darker areas of the galaxy will stand out more), which will reveal more details, including in the core.   I love M51--you have allot of details there!

Rodd

[Petergoodhew]

1 hour ago, Rodd said:

Allot of data there. IMO your galaxy is very bright and if you bring down the histogram just a bit (trial and error--but not allot), you'll have more contrast in the galaxy (the darker areas of the galaxy will stand out more), which will reveal more details, including in the core.   I love M51--you have allot of details there!

Rodd

Thanks Rodd, will give it a try.

[Petergoodhew]

2 hours ago, Rodd said:

Allot of data there. IMO your galaxy is very bright and if you bring down the histogram just a bit (trial and error--but not allot), you'll have more contrast in the galaxy (the darker areas of the galaxy will stand out more), which will reveal more details, including in the core.   I love M51--you have allot of details there!

Rodd

Done.  Yes I think that's much better.

[PatrickGilliland]

Nice work better - versions coming along nicely, you may find a little less luminosity on the galaxy actually helps in this scenario.

[Petergoodhew]

Thanks Paddy,  how about this?

or even this?

 

[Rodd]

On ‎6‎/‎13‎/‎2017 at 09:48, Petergoodhew said:

Done.  Yes I think that's much better.

I like this direction.  Now for the tricky part.  See if you can increase the contrast between the brighter fine details and the darker fine details.  They are all there.  For example, in the dark trough between the spiral arm bright ridges, there are details that are slightly brighter than the darkest regions.  Give them a little boost, and maybe drop the dark areas around them just a tad.  A bit of selective sharpening could help accentuate these areas I think.  Also--if you can isokate the core and drop the brightness you will reveal core details (the same for the core of the companion).  Great detail--the makings of a top drawer image

Rodd

[ollypenrice]

Really going in the right direction, Peter. I like the first of the two in response to Paddy's post best. 

When you get so many comments on processing it's because the image is good and the data is great - so feel encouraged!

My hunch is that maybe you've been too focused on dragging out the faint tidal structures during the process. To my mind they've occupied too much of your available dynamic range and come too close to the brightness of the spiral arms. Also, if the brighter parts are too bright they lose colour saturation easily. (I've recently been wrestling with this problem on M63. Paul Kummer, with whom I took some of the data, felt my processing was overly focused on the faint outer loops to the detriment of the galaxy. A fair point.)

M51's outer tidal structures do exist and are perfectly 'gettable' but they're faint, much fainter than the spiral structure of the galaxy. I'd be inclined to go easier on them. The stretch has also found a degree of large-scale patchiness in your background sky, which is a bit of a clue.

Is 15 minutes the max from your Spanish site? For M63 in the TEC I found a set of 30 minute L subs did beat a rather longer set of 15 minute ones. (Atik 460/TEC140 F7.)

This will keep you out of mischief for a long time to come! Great stuff.

Olly

By the way, the outer shell really does cut off in an improbably abrupt manner to the right as seen here. I always wondered if this were real but I think it is. Nature playing tricky...

[Petergoodhew]

Thanks Rodd and Olly.  I really appreciate this invaluable feedback as I learn from those who are way more more experienced than I am. I also like to see how the image evolves as it improves.

And yes Olly you are spot on, I was heavily focused on pulling out the faint wave detail which had eluded my prior attempts. I'm (slowly) learning that les luminosity can imrove an image as well as enhancing the saturation.

20 mins is about the max I can achieve in Spain.  If Per were still with us I'd be picking his brains as to how to get more as he always insisted that 30 mins unguided was perfectly achievable with a 10micron. I'm reluctantly contemplating adding an SX Lodestar one day.

Now I've more homework to do!