Ic2944

[Alchemy]

Taken over 4 nights HaRGB, 5 inch refractor, qhy9 camera,
i'm fortunate enough to have skies dark enough to shoot colour, unlike our city cousins who have to battle light pollution, i get to do something that might approximate natural colour, i say approximate, as i checked the web and there's a huge variety, so this is another flavour to add to the mix.

As Ha has been used for luminance, the surrounding sky is black, i played with bringing the value to 20 but didnt like it that much and felt it was what was recorded so it stays.

in deference to some of the trends of no stars, they are in abundance and if anything i boosted them slightly. i havent gone down the path of supersaturating the image, i could back off a curve and boost the saturation, but again its all to taste. i have had the monitor calibrated recently but.... who knows if what i see is what you see.

im sure its not perfect, and if you have critique, be sure to explain how to change it so i might learn something.

i found none of the programs i have gave me the colour i wanted so i had to mix and match and blend accordingly. programs used include pixinsight, photoshop, startools.

hopefully the rain will ease soon and we can all get some more data.

[strongmanmike]

Sounds like you had some fun processing this Clive :thumbsup: Nice, respectable work on this perennial favourite :thumbsup:

Mike

[Wilsil]

Great images.
Which 5 inch refractor do you have and on what mount?

[AdamJL]

I like this one, especially the colour palette. I'm not qualified enough to advise what could be improved, it looks great to me!

[Alchemy]

thanks mike, youre one of the old hands here, its been popular of late, glad it gets a pass from you :thumbsup:.

wilso... ive had most of this for a fair while now, given it works i havent really seen the need to upgrade, although all the automated gear these days is astounding. i am in the throes of deciding on a new camera, hence my appearance on the forum, just seeing what everyone else is doing etc.

as per pic, WOFLT132 on a G11 non gemini, guidescope is WO megrez 88, guide cam ZWO 174 using PHD2 for guiding. fortunate enough t have it all in a home made observatory, with no street lights nearby, although the glow from melbourne makes shooting east a waste of time.

[strongmanmike]

Cool looking setup mate :thumbsup: yes, automated gear, hmmm?....I'm slow on the uptake too :question:..still turning my dome by hand :(

So if it is your Eastern horizon that has Melbourne glow, I take it you aren't at Yarra Junction anymore, which is east of Melbourne..?

Mike

[multiweb]

Looks really good and detailed Clive. Nice colourful starfield too. The 3D side by side is pretty cool. :thumbsup:

[Alchemy]

Errr um yeah.... make that West. Still in Yarra Junction, Melbourne has really increased in size in the last 20 years, the glow has become noticeably worse,but to the EAST :P it’s over the mountains, there’s nothing for miles

AdamJL as far as color palette goes, from my observations of other images, the outside should be Red Ha color, the inside as it has some O3 would be magentaish, stars yellow and blue, that’s what I was aiming for, it could have a bit more balance towards the blue end, maybe a little less bright, but you can tinker endlessly.

Hi Marc .... somehow I find myself showing a picture which I wasn’t intending to do particularly, I’ve made a couple of comments on what I like in images and what I don’t, there’s room for all sorts, others can make up their own minds if you show some options.
Haven’t quite made up my mind on the new camera yet, im Looking to see just what others will do, as you’ve got a qhy9 as well, the cooling is massive, not so much on these newer cameras.

[marc4darkskies]

Okay then, I'll be the villain :question:

I like your image Clive but a natural palette HII emission neb is predominantly a pinkish-RED, not salmon coloured as yours is. This is a common issue when blending Ha into RGB. There are a few short tutorials on the web that explain the basics of such blending. Note that my critique has nothing to do with "super saturating".

Moreover, natural palette images, if that's what you were intending, are not subject to personal taste IMO. They should approximate reality as expressed in a properly calibrated RGB master.

I can correct yours easily in PS (demonstrated below) but this is sub-optimal because it's better to use original data and avoid the problem altogether (naturally).

[gregbradley]

Nice image Clive.

Overall its very good, the only improvement would be as Marcus suggests.

I use the Astrodon technique for blending narrowband. There are several ways to do it. But Don Goldman's one is quite good. Its a tutorial on the astrodon site using the screen layer mode to blend narrowband images.

I don't use screen mode though as I don't seem to get the same results as Don does.

The salmon colour comes from using Ha as red as luminance. it won't give you that rich magentish pinky red HAlpha colour. You can blend in a bit of Ha in luminosity blend mode in Photoshop but in moderation and only after you set your Ha to red and 242 in a Photoshop layer (screen mode or try one of the others until you get the look you want).

For your setup it would be hard to beat an ASI 2600m or a QHY268M (same APSc sized sensor). They are extremely popular and the 3.76 micron pixel size would suit your WO 132 really well.

This and the full frame version are the first sensors to have no amp glow, do 16 bit. They also have outstanding QE at 90%+ and still very high QE in narrowband at 75% or so. They do however give a slight horizontal banding you have to be aware of and expose accordingly.

Greg.

[Alchemy]

Villain away, you’ve made valid points and made suggestions on for improvements, your opinion is appreciated

[Alchemy]

Excellent...... will give this a go, sad thing is earlier in the processing I had similar to those colours Marcus provided, but I was convinced they weren’t right...



Those are the 2 very cameras im looking at, I’m leaning towards the ZWO at the moment. Fortunately there’s a few reviews coming out on YouTube now, so I will watch with interest.

Back to the computer to have try another repro at this object with ideas submitted. Thanks for your input

[Alchemy]

subject to marcus comments on color, i ran the raw color stretched through photometric color calibration in pixinsight.

[marc4darkskies]

Ah Ha! That's more like it Clive! :thumbsup:. Despite being such a small image, I can see it now has too much blue. A bit of colour balancing via levels in PS fixes it in a jiffy. See the before and after adjustment histograms below.

It's always a good idea to watch the histograms when your processing - this may avoid the red clipping I see at the black end of the red histograms - which implies you've lost some faint red signal.

[Andy01]

As this thread has morphed into a processing discussion, perhaps you won't mind if I just leave this here, as it's another valuable weapon to have in the processing armory :)

MARCO'S METHOD (http://www.iceinspace.com.au/forum/showthread.php?t=138473)

[Alchemy]

Too blue.... im going to have to redo it again, but not tonight. but given i used the photometric as a base......in order Photometric, 10% and 40%

will tinker more with it later... appreciate your honest input


...........

thanks for the link Andy, will review it soon, all input taken onboard.

[gregbradley]

That 3rd image, Clive, is superb. You nailed it.

Greg.

[marc4darkskies]

I don't really know what that means :lol: I talk CCDStack & Photoshop only! :D In terms of calibration if a G2V-like star looks white - bingo. FYI, since I started doing Ha blends years ago, I've based my approach on Rob Gendler's document (http://robgendlerastropics.com/HARGB.html). I also add a small amount (10-20%) of Ha to the blue channel to mimic the H-beta that is also present in HII emmision nebs. The tricky part is to rebalance the colours to be as close as possible to the RGB master. Another Photoshop method can be found at http://www.bf-astro.com/tutorial/addHa.htm. I've used this method too.



No worries Clive. Looks like you're on the right track - the third image is looking much better! :thumbsup: