LMC attempt

[kosborn (Kevin)]

Hi all,

Here is my attempt at the LMC theme. Over a couple of nights I've been aiming at NGC 2048 because with the FOV on my scope that gives me a frame that includes the tarantula nebula, adjacent nebulosities and a portion of the LMC. I tried ISO800 at 90s and then ISO400 at 120s because it's so bright and my camera is so noisy. It was really difficult to bring out colour and in the end I integrated all subs (30x each) to get this result. Overprocessed I think because the stars are a bit purple.

The closeup of Tarantula is just a separate crop of the main image (separately processed). Looking at other examples on the internet I think I could have done better. All criticism welcome, especially from any PixInsight wizards.

Kevin

[raymo]

Pretty good result, but knowing nothing about Pixinsight, I can't help with
the lack of colour, 2070 should be showing a strong green. If you are using
DSS, equalise the colour cones and 2070 will show its colour.
Regarding noise, the 100D has the sharpness increased compared to the earlier 18Mp models such as my 600D. If you reduce the sharpness, you
will also reduce the noise. You can tweak the sharpness during post
processing if required.
raymo

[PKay (Peter)]

Well done Kevin.

At least one of us has clear sky...

You could muck around with the processing for ever (i do) so take notes of what works.

Playing with the 'amount of stretch', saturation and colour balance are a few examples.

Use the 'better or worse' principle.

The PI tutorials can be tedious but a great way to learn.

[RickS (Rick)]

Hi Kevin,

The key to colour in PI (and every alternative processing package) is getting it calibrated correctly while the data is linear. Did you use BackgroundNeutralization and ColorCalibration before stretching the data? I'd be inclined to use the default settings for CC which will use the stars in the image as a white reference.

If you're feeling a little braver, plate solve your image (ImageSolver script) and then use PhotometricColorCalibration instead of ColorCalibration. PCC will do a great job even if you don't have a good white reference available. This is especially useful if the FOV is full of nebulosity or dust.

Another useful technique to bring out colour after stretching is to use a clipped Lightness mask (ChannelExtraction, or the equivalent menu button, to get Lightness then HistogramTransformation to clip the blacks.) Apply the mask to the colour image and then use the Saturation curve in CurvesTransformation to boost the saturation. The mask applies the effect only to the brighter areas.

Cheers,
Rick.

[PKay (Peter)]

Pay attention guys an girls.

Rick knows

[rcheshire (Rowland)]

Kevin. They are fine detailed shots. What Rick said with PI.

[kosborn (Kevin)]

Thanks all.

And thanks for the PI tips Rick. I have a long way to go with PixInsight and am plodding through the tutorials at the moment. Last night I went to a dark sky site (Orroral Valley outside of Canberra at the old tracking station). Not a single cloud in the sky and incredible clarity until the moon came up around midnight. I shot some new targets and some I'd done before from a suburban backyard so it will be interesting to compare them.

Cheers, Kevin

[kosborn (Kevin)]

Originally Posted by RickS

If you're feeling a little braver, plate solve your image (ImageSolver script) and then use PhotometricColorCalibration instead of ColorCalibration. PCC will do a great job even if you don't have a good white reference available. This is especially useful if the FOV is full of nebulosity or dust.

I tried ImageSolver and PhotometricColorCalibration on a different target (Needle Galaxy) and it seems to work well but perhaps still a green tinge. Is it still appropriate to use SCNR to remove green after using PCC or should PCC itself remove any excess green in the image?
Kevin

[RickS (Rick)]

Originally Posted by kosborn

I tried ImageSolver and PhotometricColorCalibration on a different target and it seems to work well but perhaps still a green tinge. Is it still appropriate to use SCNR to remove green after using PCC or should PCC itself remove any excess green in the image?

Hi Kevin,

I don't think I've needed to run SCNR on a PCC calibrated image before but I certainly do treat it as a basis for further tweaking. I wouldn't judge you if you prefer the look after SCNR I have the advantage of remote scopes and lots of data which may make a difference...

Cheers,
Rick.