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M51 Whirlpool Galaxy LRGB (Atik 490ex)


x6gas
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The clear, if short, nights this week have allowed me to redo the luminance I'd captured of M51, and indeed capture more data than I have previously. I actually think I have enough luminance to push the stretch a little further and get some more of the nebulosity but I didn't want to over-process this attempt...

The luminance subs are of very variable quality but in this process I stacked the lot and let the sigma average routine in AstoArt sort it out. I'll probably go back and use the best 6 or 8hrs worth at some point to see if it makes a difference...

Unfortunately there is a slight tilt in my imaging train arising from the focal reducer not being seated properly - d'oh!

The colour is the data that I captured at the beginning of May... 41 t-shirt flats applied to the data.

Data: L = 118 x 300s (binned 1x1); R = 25 x 100s (binned 3x3); G = 25 x 125 (binned 3x3); B = 25 x 150 (binned 3x3)

Scope: 11" EdgeHD with Optec Lepus 0.62 focal reducer

Mount: CGEM DX

Camera: Atik 490ex

Guiding: QHY IMG0H, Atik OAG, PHD

Stacked in AstroArt 5, L, R, G, and B channels registered in RegiStar, processing in PhotoShop CS2.

This version is basically as the data dropped out, with no processing other than stretching and colour combine:

gallery_11821_2478_8449.png

This version has high pass sharpening applied and the saturation boosted:

gallery_11821_2478_326959.png

And this has the saturation tweaked still further:

gallery_11821_2478_594026.png

I'd really welcome comments on whether I am over-sharpening (the data from the Atik 490ex does seem to allow you to push the high pass insanely high, more than I've done here, but I'm probably getting carried away as it is) and whether I'm pushing the colour too hard.

Thanks for looking, Ian

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Fantastic detail Ian. For me, looking on a small tablet I reckon it is just slightly over sharp, but not by much, if I checked on a decent screen it might be spot on. I like the colour in the last one very much.

With your Lepus 0.62 did you need to get a spacer made to suit the camera and filter wheel?

Robin

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Fantastic detail Ian. For me, looking on a small tablet I reckon it is just slightly over sharp, but not by much, if I checked on a decent screen it might be spot on. I like the colour in the last one very much.

With your Lepus 0.62 did you need to get a spacer made to suit the camera and filter wheel?

Robin

Thanks Robin.

Actually looking at them on screen now the background looks a bit too light too...

The Lepus has an ideal backfocus of 105mm. I have a 2" nosepiece on the OAG which screws directly to the circular dovetail that attaches to the reducer using a 2" filter thread. That gives me almost exactly the correct backfocus. If I needed to tweak it then I could use 2" extensions or t-thread extenders on the camera side.

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You've created a very fine Image of this popular target.

Processing is nigh on impossible to get perfect, and results will judged differently by others.

Satisfy yourself Ian, but when constructive suggestions are put to you, there is no harm in trying them out.

I'm not an expert by any stretch, but I love to see these Deep Sky Images by SGL's AP's.

Personally, I would be quite pleased with any of these three, although DrRobin

may have a point about the slightly over sharpened version.

Nevertheless, a great job mate :icon_salut: .

Ron.

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Processing is nigh on impossible to get perfect, and results will judged differently by others.

Satisfy yourself Ian, but when constructive suggestions are put to you, there is no harm in trying them out.

Thanks Ron. I do agree to a point, but I also find that spending hours processing it's really easy to lose perspective and so the opinions of others are really important. That or coming back a week or so later and taking another look myself which is perhaps what I should do, but I'm usually impatient to post!

I think the issue is making incremental changes - it's easy when sharpening, for example to sharpen a bit more, compare to what you've done before and think it's an improvement; that's why I posted the unsharpened version as a reference. It's the same with colour...

So here are another couple of versions with the high pass toned down a bit and the black point moved in:

gallery_11821_2478_437754.png

This one has the colours tweaked a bit to make the blues more natural, but I suspect many will find it too green:

gallery_11821_2478_295107.png

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Great image.. and frankly much better colour, galaxies are not bright blue.

With the better balance the HII regions are starting to appear, as they should

Derek

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I agree with walking away from an image for a week and coming back to it. If you stare at an image too long and process for hours at a time you may find yourself chasing your tail. I find your M51 to be spot on. I personally do not find it too sharp and I find your last image from the OP to be very pleasing to the eye. Well done!

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Actually the last image you posted is by far the one call "FINAL CUT". I find the background to be perfect and you pulled some nice galaxy detail without looking overprocessed.

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The last version is excellent. The background level is spot on for my monitor :smiley:

M51 s a wonderful object and also for the sprinkling of back ground galaxies that are throught.

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Great image.. and frankly much better colour, galaxies are not bright blue.

With the better balance the HII regions are starting to appear, as they should

Derek

Thanks Derek.

Yes, I see a lot of galaxy images where the colours are pushed way too much IMO. Thanks for your comments.

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Thanks Superdavo, Steve (broca), 1parsec, AndyO, and Ewan.

I do prefer the last one too, but I know that some folk will find it not blue enough! I am encouraged by you all though. I know this is a popular target, but I really do think it's so interesting and I am pleased to have a half decent version of it.

Thanks again!

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Thanks as always Gina.

This was actually not difficult to process - plenty of data for the luminance helps - but I am surprised at just how little R / G / B I can get away with...

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That's a stunning image Ian! The fact that you can play around so much with colour and other tweaks without 'degrading' the image points to quality data I would think.

Thumbs up!

/Jesper

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Mate, I'd be more than happy to put my name to any of these but if I absolutely HAD to pick a favourite then I guess it would be the 1st image on the second set of images (on my monitor anyway). Not sure what the "real" colours are supposed to look like but in all honesty to me it's not critical. hence the hubble pallette :)

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That's a stunning image Ian! The fact that you can play around so much with colour and other tweaks without 'degrading' the image points to quality data I would think.

Thumbs up!

/Jesper

Thanks Jesper. Yes, lots of data certainly helps and comparatively speaking this was a doddle to process - probably took me an hour or so. The data actually has more to give. With careful processing I am pretty sure I can get more of the nebulosity surrounding M51b (NGC 5195).

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Mate, I'd be more than happy to put my name to any of these but if I absolutely HAD to pick a favourite then I guess it would be the 1st image on the second set of images (on my monitor anyway). Not sure what the "real" colours are supposed to look like but in all honesty to me it's not critical. hence the hubble pallette :)

Thanks Scott. As to colours, yeah, it's all about what looks good IMO. Trouble is, the final rendition looks perfect on my laptop and home desktop, but is indeed too green on my monitor at work. My problem is, I don't know which monitor is calibrated correctly!

Thanks for the encouragement!

Ian

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