Helix from Astrofest - Reprocessed less green.

[batema (Mark)]

What a fantastic camp this is and I only wish I could have stayed longer. 2 hours Luminance at 10 min subs at 1x1 binning, and 50 min at 5 min subs 2x2 binning in each RGB channel. Camera is a QHY-9 at minus 20c.

Taken through W/O Flt 110 with darks and flats applied and processed in photshop. Any comments welcome.

Mark

[strongmanmike (Michael)]

Well done Mark, even got some of the faint outer-outer stuff juuust glimpsing through sounds like a camp in Heaven

Mike

[Garbz (Chris)]

Beautiful, and I'm jealous. I couldn't make astrofest and tried to image this one in the burbs the other day. What a failure that was.

One thing I should mention though is your image has an extreme green cast from the sky all the way to the highlights in the stars, but not in the extreme dark portions of the image. The green cast also seems to be a gradient stronger in the top right of the image.

I hope I'm not out of place but I've posted an example from a quick photoshop curve to correct the green:

[[1ponders] (Paul)]

very nicely done Mark. Glad you guys had a good time.

[batema (Mark)]

Thankyou all. I think any astro camp would be a great camp Mike. Dave was talking about your Transit trip and it sounded like a lot of fun. Chris any advice is good advice and I will give it a go Thanks.

Paul it was great and clear nights for the first four we were there. Just a bit of a bummer with the fog but still great. And quite warm as I only saw the temp get to 0 degrees which is almost boardshorts and Tshirt weather.

[Ross G]

Amazing photo Mark.

Great colours and excellent detail.

Ross.

[batema (Mark)]

I have adjusted the green channel which when I look I can now see the green across the field. Comments welcome but also if someone can give me advice on the quantum efficiency of the chip in terms of sensitivity to colour. I was told that the chip of the qhy-9 in terms of green sensitivity being 100% that the red is about 50% and Blue is like about 48%. So to get the same amount of intensity of colours if I shot green subs for 5 minutes then I should shoot red subs for 10 min and blue for like 11 min OR DO I JUST SHOOT THEM ALL AT THE SAME LENGTH???????

Thank you

Mark

[Garbz (Chris)]

I can't help with your question since I shoot colour not monochrome but I must say your new edit looks much better.

Interestingly whatever is contributing to the green is not even across brightness. Your darks are currently spot on (points 1 and 2 on my attached screenshot), yet your highlights (points 3 and 4 centred on stars) are still slightly green. This could be to do with the fact that the green is corrected at the end of the processing, I don't know.

When I was playing with photoshop a colleague directed me to a free plugin called Hasta La Vista Green. http://blog.deepskycolors.com/archiv...sta-green.html while it may not fix the source of the problem it may work well as an interim solution.

[Geoff45 (Geoff)]

Originally Posted by batema

I have adjusted the green channel which when I look I can now see the green across the field. Comments welcome but also if someone can give me advice on the quantum efficiency of the chip in terms of sensitivity to colour. I was told that the chip of the qhy-9 in terms of green sensitivity being 100% that the red is about 50% and Blue is like about 48%. So to get the same amount of intensity of colours if I shot green subs for 5 minutes then I should shoot red subs for 10 min and blue for like 11 min OR DO I JUST SHOOT THEM ALL AT THE SAME LENGTH???????

Thank you

Mark

Much better colour in the repro. Not sure which software you are using to colour combine, but my normal procedure in the past was to do the same length RGB and then use Excalibrator http://bf-astro.com/eXcalibrator/excalibrator.htm to determine the colour ratios in CCDStack. Now I still take 1:1:1 ratios, but calibrate with PixInsight.
Geoff
Geoff

[RobF (Rob)]

Nice work Mark. I generally have to pull the green curve down a bit and boost blue a tad too for the QHY9 from dark sky sites (more work required from urban skies).

Sorry didn't get a chance to say hi - I did wander over to the big "mission control" table a few times to find it on autopilot. Must have been coffee break time

[batema (Mark)]

Will have to try top get out to 10 chain and catch up. Look forward to some of the shots you have taken Rob. The last one I saw was a galaxy I think that was stunning.