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Bob Andersson

The Pleiades

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Oh my, I do love Pleiades, so majestic and so blue. Well Bob think you missed astrophtographer of the year this time round but i really would expect to see this entered for next year. :grin:

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fabulous image. This has got to be one of the best I've seen of this familiar object, just so much detail.

Derek

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I absolutely love the detail and structure in the nebulosity but feel that the colour balance is a long way out in the fainter regions. The entire image is blue with a blue-magenta background when in fact the background sky has some deep, faint reds in there I think.

The faint stuff I mean can be seen in this version by Tom O'Donoghue http://www.flickr.co...157617210650819 and is pretty much what I found when I imaged it in a smaller apo: http://ollypenrice.s...OSITE-FL-X3.jpg

It would be interesting to see the histogram in the three colours because I think your reds are not standing up for themeselves yet! Fabulous structure though. I think I need to get some luminance from my TEC to pull out some of the structure you've caught...

Olly

Edited by ollypenrice

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Hi Olly,

Fair call. The emission nebulosity shows more clearly in my 200 second RGB image so I need to hone my processing skills as adding the RGB image as a screen layer over the blue 200 plus 1,0000 second data, while working well for the stars, isn't quite working well enough for the nebulosity. I'm thinking maybe an intermediate "Colour" layer above the 200 plus 1,000 second data, that layer produced from a "no stars" version of the 200 second RGB image, perhaps with selective masking to feather the boundaries, to modify the way the 200 plus 1,000 second data is coloured but maybe there's a simpler way?

Bob.

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Bob,

The dust is normally visible after long exposures. The total integration time is not enough to show it.

I think the reason it's so blue is that you probably used additional Blue exposures as Lum. I think you need to blend it to blue as Ha is added to Red.

For the dust you need much more red.

Mark

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I absolutely love the detail and structure in the nebulosity but feel that the colour balance is a long way out in the fainter regions. The entire image is blue with a blue-magenta background when in fact the background sky has some deep, faint reds in there I think.

The faint stuff I mean can be seen in this version by Tom O'Donoghue http://www.flickr.co...157617210650819 and is pretty much what I found when I imaged it in a smaller apo: http://ollypenrice.s...OSITE-FL-X3.jpg

It would be interesting to see the histogram in the three colours because I think your reds are not standing up for themeselves yet! Fabulous structure though. I think I need to get some luminance from my TEC to pull out some of the structure you've caught...

Olly

I agree Olly it is very biased to the blue but has excellent detail once the colour balance is sorted it would look stunning.

Regards

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Hi Mark,

Sorry, but I'm not understanding you. The dust is clearly visible so the integration time was by definition long enough to show it. :evil::laugh:

It is true to say that the 1,000 second blue subs were only just enough to show that extended reflection nebulosity in any detail as I was very close to the noise floor. To get a similar signal in green, let alone red, would have required a huge increase in imaging time and I'm not sure that longer green and red subs would have provided much variation in colour in the fainter bits although it would have been scientifically more appropriate to at least have tried I suppose! I'm still on a learning curve but common sense, sometimes a dangerous guide, would suggest that colouration issues will arise in any event for all faint and/or extended coloured objects as one or more of the channels (red and green in this instance) hit the noise floor before the channel with the strongest signal.

As I mentioned in my reply to Olly, I do readily acknowledge an issue in that I still haven't made as good a use of the 200 second RGB data that I have to show the emission colouration below Merope.

My choice of colour for the extended reflection nebulosity is, I admit, a bit "in your face" and not strictly photo-realistic. But when I went for a more cyan rendition I felt that the result lacked punch and, to be brutally honest, I wanted my image to ask a question - namely why so few images of the Pleiades show that extended reflection nebulosity when I could so clearly see it in the data after just 5 x 1,000 second blue subs? Maybe the devil in me won out and I should have gone for a quieter rendition but I'll plead artistic privilege on that one if I'm allowed. I'm heartened to see that, if for no other use than as wallpaper :laugh:, my photo has pleased the eyes of many here on the forum.

I do appreciate the feedback. Praise is always nice but also the more critical feedback is also welcome if it can help me improve. :cool2:

Bob.

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Obviously a lot of work has gone into producing this wonderful image. As a visual-only observer I sometimes find it hard to understand how real these sort of images are. To paraphrase a mathematical quote, God made the pixels; all else is the work of man.

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I sometimes find it hard to understand how real these sort of images are.

I think you might have to spend a bit of time tying down what you mean by "real" before you can get anywhere with that one :)

James

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Hi Mark,

Thanks for sharing a brilliant image, one that I might try to emulate with my 165mm Pentax lens one day. As I understand it the red component in that image is pretty much entirely down to a diffuse H-alpha signal so maybe I'll do some H-alpha subs when time permits.

Bob.

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Bob, I often find your descriptions of processing incredibly complicated. Mine are much simpler; I colour balance the RGB in Pixinsight and stretch it to the noise limit in Ps using levels and curves. I strectch the L to the noise limit in Levels and corves and then work on local contrasts. I may sharpen the bright stuff, excluding stars, and maybe noise reduce the faint stuff. Then I apply the L and that's it. <the rest is detail.

Are the colours real? Yes, if you colour balance properly they are.

Olly

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I hope you've sent this off to every astro mag and competition in the land - next to some of the wide field work of Greg Parker, planetary work of Ian Sharp and the dso's of Peter Shah this has joined the top of the list in my favourites catalogue - very well done. :smiley:

David

Lovely image with loads of structure - Need to ad Olly to that list I think....

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