Orpington Astronomical Society

Astronomy => Astrophotography => Topic started by: Carole on Apr 11, 2016, 00:41:58

Title: M101 Kelling Heath now tweaked
Post by: Carole on Apr 11, 2016, 00:41:58
As stated on the Kelling thread, the skies cleared at 1am approx.  I was expecting to be able to get more data than this, but unfortunately had to do a meridian flip, and by the time I had sorted that out the skies had deteriorated, and so I only got a total of 1 1/2 hours.

This is the LRGB version:
4 x 600secs Lum
3 x 150secs binned each of RGB
Skywatcher ED120 and Atik314L + FR x 0.8

(http://gallery.orpington-astronomy.org.uk/albums/userpics/10047/normal_M101_LRGB2.png)

This is the HaLRGB version with  3 x 600secs Ha added

(http://gallery.orpington-astronomy.org.uk/albums/userpics/10047/normal_M101_HaLRGB_Kelling_2016.png)
Title: Re: M101 Kelling Heath
Post by: MarkS on Apr 11, 2016, 05:48:55
That's a good result for the short total exposure.  It looks excellent with the H-alpha added.

Mark
Title: Re: M101 Kelling Heath
Post by: The Thing on Apr 11, 2016, 08:28:46
I'd be happy with that Carole, The Ha regions really stand out and I can see plenty of wispy bits.
Title: Re: M101 Kelling Heath
Post by: Carole on Apr 11, 2016, 10:21:53
Thank you Mark and Duncan.

Carole
Title: Re: M101 Kelling Heath
Post by: JohnP on Apr 11, 2016, 11:47:46
Have to say Carole looks very nice & nicely processed to. You seem to have reached a nice solution with your process workflow.. Not too sharp, Not too noisy, Not too saturated.. youve been posting some nice images recently...

John
Title: Re: M101 Kelling Heath
Post by: Carole on Apr 11, 2016, 12:13:09
Thanks John, I must say I have in the last few months made a few resolutions with regards to processing (things to improve on and things not to do) and it seems to be working. 

Carole

Title: Re: M101 Kelling Heath
Post by: RobertM on Apr 11, 2016, 14:00:24
Very nice that Carole, especially for such a short total exposure.  To me the Ha component looks a little vivid on my screen, did you blend it in as Ha+Hb (70%+30%) or just into the Red channel ?

Robert

PS. yes I know I should get my monitor calibrated !

Title: Re: M101 Kelling Heath
Post by: Carole on Apr 11, 2016, 14:21:53
I didn't do either Robert.
I don't have an Hb filter, and have devised my own way of blending in Ha.

I convert the Ha image to RGB and then place the LRGB image over the top and combine as Blend mode lighten.  I then switch off the upper LRGB layer and stretch the lower Ha layer in red in curves after having anchored down the black and white points, and then switch the LRGB layer back on and the red Ha bits will then show through.

Sometimes I have to do this in more than one iteration or trial and error using varying %s until I get it right.  But seems to work OK.

Doesn't look vivid on my screen.

Carole
Title: Re: M101 Kelling Heath
Post by: RobertM on Apr 11, 2016, 15:10:31
Hi Carole,

I think I risk confusing you so I'll leave it to when we next speak.  Suffice it to say, try adding your Ha signal to Blue with 20-30% transparency on the Ha signal.

Robert
Title: Re: M101 Kelling Heath
Post by: Carole on Apr 11, 2016, 16:35:06
I think I understand that Robert, but don't understand what that will achieve.  I'll give it a go and see what happens.

By the way, I tried in the past adding Ha to the red channel and it just didn't work with horrible results.  It was just messing around trying different things when I stumbled on the method I described above.

Carole
Title: Re: M101 Kelling Heath
Post by: RobertM on Apr 11, 2016, 17:23:18
There are numerous workflows that people use and I think it's a case of which one gives you the results you most like.  The small change may be worth trying - nothing ventured as they say.

Robert
Title: Re: M101 Kelling Heath
Post by: Carole on Apr 11, 2016, 19:20:07
I tried that Robert.  It seemed to slightly increase the blue in the background nebulosity. 

Carole
Title: Re: M101 Kelling Heath tweaked
Post by: Carole on Apr 12, 2016, 13:42:34
I discovered there was more I could get out of the luminance data, so this is a revision:

(http://cdn.astrobin.com/images/thumbs/25eacac4bd4cf748b31df3c8464894aa.1824x0_q100_watermark.jpg)

(http://cdn.astrobin.com/images/thumbs/a7cf82fe2253fbb23e4a1cd785713312.1824x0_q100_watermark.jpg)
Title: Re: M101 Kelling Heath now tweaked
Post by: Fay on Apr 12, 2016, 17:37:14
Thats a good final image Carole! Nice depth and colour

Fay
Title: Re: M101 Kelling Heath now tweaked
Post by: Carole on Apr 12, 2016, 20:33:21
Thanks Fay.

Carole