First go Carina nebula with basic tracking mount

[zenith (Tim)]

Hi,

I borrowed a friends Celestron STL mount and had a go at the Eta Carina Nebula from suburban Melbourne. It was also my first attempt at using dark/bias/flat frames (only one of each). I used DSS and adjusted the image after stacking and then made a few more subtle changes in GIMP.

I am happy with the result, but I am not sure how far to push the settings, initially I had the colours looking overcooked and fake, then I had the centre washed out and over exposed.

Are there any rules of thumb when stretching levels or adjusting brightness/contrast and mixing RGB channels? I basically tried to get rid of the overall purple tint (and make the sky black) but still try to have the colours look like the original, but pop a bit more.

Canon 6D, Saxon ED80, 9 subs of 20 secs @ ISO 3200.

Advice/suggestions welcome. Thanks.

[Mosc_007 (Charles)]

Pretty good for a first attempt. Nebula looks good.

Their is some vignetting though. Maybe you need more Flat Frames.

As for Colours I think it comes down to personal preference. Although sometimes it gets taken a bit to far.

It all takes plenty of practice and experimenting with different tools.


Charles

[Robert9 (Robert)]

That's a great first effort Tim. Good detail. Your image shows a slightly larger area than a recent one of mine with an ED100. I think the ED80 is f7.5. The ED100 is f9.
What did you use to stack your images?
With regard to colour, I look at each of the RGB channels individually and adjust them to bring the black level to the LH base level of the histogram.
The RH end I bring in until I get the desired white level, then adjust the centre for the best depiction of the mid-ranges. Repeat this for each of the RGB layers, then a final tweak with all (RGB) of them. Its a bit of a fiddle but as Charles said, personal preference. Have a peak around and see what others do, then do it the way you want.
Where about in suburbia are you?
Robert

[kosh]

Nice effort there Tim,

The ED80 is a small scope, and at F7.5 you cant expect much at 20secs so you've done pretty well. You would get more if you could manage maybe 30+ subs at 20 secs. You will be able to stretch much more before all the noise comes out too much.

As for colours, if you just stretch the histogram naturally, and don't play much with saturation etc. you should get a good feel for the natural colours of the subject. I think once you start fiddling with hue/saturation, and moving the individual channels around separately, that is when things tend to get a little funky.

Goran.

[Robert9 (Robert)]

Originally Posted by kosh

Nice effort there Tim,

that is when things tend to get a little funky.

Goran.

Great description Goran. Couldn't think of a better way.
Robert