M51 HaRGB

[Zakalwe]

HaRGB M51 by Stephen Jennette, on Flickr

4 hours of 10 minute Luminance exposures.
2 hours of 20 minute Hydrogen-alpha
6 x 5 minutes exposures for each RGB channel.
Total 7.5 hours exposure.
H-a data blended into both Red and luminance channels.
Altair Astro 115mm Triplet.
Atik 428 mono camera.
Baader LRGB and H-a filters.
Photoline 0.79 reducer.
All mounted on a Skywatcher EQ8 and controlled with Sequence Generator Pro.

Thanks for looking

[Chris]

Lots of data there, very nice rendition, I probably go too rich with my colour, yours is nice and subtle.

[michael.h.f.wilkinson]

VERY nice. Loads of tidal tail structure resulting from the interaction visible

[red dwalf]

very impressive.

i like this a lot. 

[Stephen Green]

 That is a great image I like the detail

   Stephen

[dazza1639]

Looks like you've got to the bottom of your eggy stars great picture mate

Darren

------------------------------------------------

Twitter: @SalAstroSoc @Astronut1639 www.salfordastro.org.uk

Nexstar 8 GPS ADM MDS Rings & Counter Weights, Skywatcher ST80 & Synguider, Canon EOS 1000d,

Dew Heaters & 4 Channel Controller, Orbit Wedge, Observatory and not enough clear nights

[Zakalwe]

Thanks all for the kind comments. I'm sure that there's more to be had out of this one with better processing. I'd like to see the Ha showing through more.

Re the eggy stars...I whipped the worm block off amd re-lubed the wheel. I tightened up the backlash a tad too. Job jobbed.

[Ewan]

Good image processing there.

We'll done

[SteveA]

Very nice image Stephen. I would agree with you though, there definitely some detail in the Ha that you could bring out there.

Just wondering.....what do you use for processing?

[Zakalwe]

Very nice image Stephen. I would agree with you though, there definitely some detail in the Ha that you could bring out there.

Just wondering.....what do you use for processing?

Thanks Steve,

I stack in DSS and process in Photoshop, but I do need get more Ha data and to re-process what I've got.

The Ha was 6 x 20 minutes, but it is pretty grubby (straight out of DSS):

I've then blended this into the Red data (Normal blend mode, 30% opacity). This was used to replace the Red channel. I also blended some of this into the Lum data (at about 15%). This is the combined Red and Ha data (pre-noise reduction).

I have had a bit of a fiddle with the image to tidy up a few bits and pieces, but I think that I need to re-do the whole shooting match.

[SteveA]

Hi Stephen,

I was a bit surprised there was not much red coming through, I reckon you have a fair bit of Ha data there. I imaged this a couple of years back and merged in a very small amount of ha data which showed up surprisingly well in the red channel. I'd post it here again but having just looked at it again I now feel slightly embarrassed by the egg shaped stars...which a couple of years ago I thought were acceptable!

Steve

[Zakalwe]

Hi Stephen,

I was a bit surprised there was not much red coming through, I reckon you have a fair bit of Ha data there. I imaged this a couple of years back and merged in a very small amount of ha data which showed up surprisingly well in the red channel.

It's probably due to my cack-handed processing. I need to learn how best to add in the Ha data.

[SteveA]

Believe me..I'm no expert. Every attempt I have at image processing is a veritable trip into the unknown! Though having said that I find Pixinsight is pretty good and once you get used to it it's fairly friendly. I also get some fairly consistent results with it...

Steve

[Zakalwe]

Believe me..I'm no expert. Every attempt I have at image processing is a veritable trip into the unknown! Though having said that I find Pixinsight is pretty good and once you get used to it it's fairly friendly. I also get some fairly consistent results with it...

Steve

I played with PI once or twice and it confused the bejabbers out of me.

[SteveA]

I just followed the Harry Page tutorials...surprising how quickly I picked it up. I found it a lot easier the PS...I really couldn't get on with that!

[ollypenrice]

Under no circumstances would I use Ha for luminance on a galaxy. It will light the entire image with its own structure and this structure has precious little to do with most of the galaxy. It will serve to damage the real brightness distribution which is to be found in the luminance layer. Nebular Ha does contain real structural detail and a case can be made for a light application as luminance if the nebula in question is Ha dominated. However, in 99% of cases in amateur scopes galaxy Ha is little more than a series of blobs where diffuse HII regions show themselves. They are too remote to show real detail. To my mind galaxy Ha picks up the star forming regions nicely and brings a bit of colour zing to the sprial arms in places but, unlike nebular Ha, it has nothing to add to overall structure. I'd add it to red in blend mode lighten and keep it a mile away from the luminance channel.

Olly.

[SteveA]

Please ignore the egg shaped stars then.....

There's about 45 mins of Ha data in this and as Olly indicated this can be seen as blobs in the spiral arms.

[Zakalwe]

Under no circumstances would I use Ha for luminance on a galaxy. It will light the entire image with its own structure and this structure has precious little to do with most of the galaxy. It will serve to damage the real brightness distribution which is to be found in the luminance layer. Nebular Ha does contain real structural detail and a case can be made for a light application as luminance if the nebula in question is Ha dominated. However, in 99% of cases in amateur scopes galaxy Ha is little more than a series of blobs where diffuse HII regions show themselves. They are too remote to show real detail. To my mind galaxy Ha picks up the star forming regions nicely and brings a bit of colour zing to the sprial arms in places but, unlike nebular Ha, it has nothing to add to overall structure. I'd add it to red in blend mode lighten and keep it a mile away from the luminance channel.

Olly.

Thanks Olly.

I'm clearly going to have to re-do this.

Please ignore the egg shaped stars then.....

There's about 45 mins of Ha data in this and as Olly indicated this can be seen as blobs in the spiral arms.

That's the effect that I was trying (and failing) to achieve.

[ollypenrice]

Have a go at Ha added to red in Blend Mode Lighten. Here are a few things that work for me...

In this mode the Ha is only applied to red where it is brighter than red. You can, therefore, do a brutally hard stretch, well above the noise floor on the darker parts, because they won't be applied. A luxury!

When you have your Ha as a layer in this belnd mode you can blink it on and off to see what it's adding to red. If the answer is 'not much' - as is often the case - you can just lift it in curves while it's sitting over red until it does do something. By holding down the bottom of the curve you can be sure that the noisy parts won't be applied.

Flatten, merge channels and save as HaLRGB.

If it has made a good job in some places and a mess in others, paste it on top of the LRGB and simply erase the messy bits. You can also lower the opacity at this point if it's looking overdone, too.

Olly

PS A notable exception to the 'no Ha detail in galaxies' dictum is M106 where the incomparable R Jay GaBany found rather a lot!

PPS Have a glance at your colour channel alignment. I think red's a bit out.

[Zakalwe]

Many thanks Olly...some great tips in there.

I did blend the Ha in pretty much as you advise EXCEPT I was being too timid with the stretches. With the Lighten blend mode it barely made any difference as I was afraid of stretching it as it was noisy.

I shall sally forth and do it again and this time give it the full Stretch Armstrong!