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Whirlpool Galaxy M51 - modded DSLR


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my first DSO pic in aaaages, since October last year in fact, large doses of real life have been getting in the way.  A very common target, but my best take of it by a long way:

27163033784_2b6f393ff1_c.jpg

18x 420s lights at ISO1600, bias darks and flats, 1.5x barlow, equipment as per sig, developed in Pixinsight.

 

And just for a laugh, here is my previous effort:

Whirlpool.jpg

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a massive improvement. Great job!

Maybe my screen is not calibrated right, but you're background seems very very dark, maybe you clipped the blacks a little high? But absolutely nothing else to moan about, beautiful picture :)

Kind regards, Graem

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13 hours ago, graemlourens said:

a massive improvement. Great job!

Maybe my screen is not calibrated right, but you're background seems very very dark, maybe you clipped the blacks a little high? But absolutely nothing else to moan about, beautiful picture :)

Kind regards, Graem

Hi Graem,

I think i am perhaps a victim of screen calibrations - it's definitely not clipped, I'm very careful about that, but on the laptop I use to process it's actually still a little light for my tastes, about right on the home desktop (even though both are supposedly gamma calibrated) and a little dark on this screen at work.

Maybe I should just aim for a given numerical background level.  Do other people think the background is too dark too ?

 

Cheers

 

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Hi Stuart.

I know exactly what you mean, i always go too dark if i use my old monitor at home.

Now i got used to just knowing the 16 bit value (for me i go for 6000-7000) and in photoshop in RGB mode i have heard most people target 20-30 (8 bit)
But i guess this is like most things in AP, everybody can do it as like like, and in the end you must like it :)

I have seen though, if you go too dark, and then you print it, printing in most cases will make it even darker, so lots of detail gets lost.

Kind regards, Graem

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3 minutes ago, graemlourens said:

16 bit value (for me i go for 6000-7000) and in photoshop in RGB mode i have heard most people target 20-30 (8 bit)

hmm, so a % value of about 10% - I'm definitely lower than that, to be honest I usually target about 3.5%.

I'll have another little play with it this evening (fortunately that stretch was the very last step !), see how it looks with a lighter background

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cheers

Celestron Omni XLT150 newt (150mm ap, 750mm fl, f/5) +coma corrector, AZ-EQ6GT, QHY5L11C+ T70 guiding, modded Canon 1100d

I used the Canon 1100d through a 1.5x barlow (I know you're not supposed to, but I think i got away with it)

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how does this one look ?  Background is a bit lighter now, about 8%, any more looks a little washed out to me, though that could be the gamma on this screen still (which I've just re-done)

27744424001_ea4ff8d565_c.jpg

 

3 minutes ago, giorgio_ne said:

Great, great image! Are you located on a dark site in Spain, as per your signature, or in London as per your profile settings? Just curious...

Hi Giorgio, thanks very much !  I live in London, (Dulwich, not far from you !) but to be honest I don't bother doing any astro here due to our light pollution.  We've got a small place in Spain in the middle of nowhere though, so when down there I do enjoy some lovely skies.

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Oh i love that version so much more!

To me at the beginning also the goal was to keep background as dark as possible, but as the sky is not dark at all (indeed it is very bright!) my opinion is that this represents (to the eye) more the actual sky (but i must admit, that i gradually adapted this opinion from experienced astrophotographers around the globe)

Kind regards, Graem

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thanks !

There is some noise reduction, yes, though the camera is not too noisy.  I find  MLT Transform n/r and then TGV denoise is a good combination in Pixinsight, but I deliberately dialed it back several steps from where the noise is 'removed', and let some of the noise survive, I think it helps it to look more realistic and in-focus if there's a touch left in there.  If you zoom in on the tidal tail bits for example, you'll see some.  I was more brutal in removing chrominance noise though.

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Hi Glowingturnip,

I was just scrolling through this post. Liked your improvement a lot! But my first thought was that the background was very dark and that you should be able to get some of the wisps I've seen in other posts with this kind of quality data. Further down I noticed that I'm not the first with this thought and finally reached your new processing attempt. And NOW you are spot-on. Would love to have a go at this target but, alas, I live on the wrong side of the world...

Nice going :)

HJ

 

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