Large Magellanic Cloud

[Rowland]

LMCST.jpg (216.89 KiB) Viewed 10288 times

Large Magellanic Cloud - cooled DSLR -5C, 200mm prime lens/6.3 f, 72 x 2min sub-exposures @ ISO1600.

RGB Luminance Retention to illustrate the wonderful color variations.

The lens is not capable of pinpoint stars and precise focus is near impossible.

Rowland

[admin]

Very colourful indeed, showing clear differences in emissions dominance of the various areas. I'm wondering though if the purplish area to the left is a real phenomenon or and artifact (gradient?) I'm not aware of such large Ha, N2 or S2 dominant areas which could explain this color... Any ideas?

[Rowland]

It is very colourful and following several different approaches to processing, I think you are correct Ivo - the area to the left may be gradient.

I had problems at full resolution, leaving a blue gradient/color cast. Binned, the image appears to Wipe successfully, but perhaps not?

How agressive can I be with Wipe?

The optical train has a clip-in uv/ir filter with all other filters removed. All light leaks are sealed and irrespective of sky conditions I get a very strong dark blue cast over all the image or blobs depending on the Wipe mode I use.

This image was taken under a reddish suburban sky (sodium).

I have a handle on Decon now with much better results - defaults work very well. I don't know why I attempted generating my own mask, the auto mask is excellent.

[Cheman]

Rowland
If you havent already, try increasing the dark anomaly filter setting in wipe. It should get rid of that blue cast. It works on my images when I have that problem
Che

[Rowland]

Thanks Che. I will give that a go.

[Rowland]

LMC screenshots, post Wipe and processed. Decon looks better. See next post for vignetting removal.

[Rowland]

I ran Wipe twice on this iteration. The first time with 100 ROI and the second with vignetting. I suspect the flats (iso100) are at fault with uneven illumination. Will try with the second set taken at iso1600. Stars are blown and it could do with more dynamic range, but this seems a more realistic version of the area.

High res

[admin]

That last rendition seems to be spot on! It still shows ample of colour, while IMHO the busy star field does not detract at all from the detail in the LMC and neighboring objects.

If you're worried about Wipe removing nebulosity in a particular area, just mask it out with the lassoo tool, so that Wipe won't sample it.

[Cheman]

Very nice job Rowland.
Che

[Rowland]

Thanks for the help. Got me on track. That seems to be more realistic. The regularity of the area of vignetting was in hindsight a give away. I will be more discerning in the future.