A Bi-Colour poet

[strongmanmike]

I've done this before a year ago but the conditions were pretty good and having the new camera with stable OAG plus small pixels and it's such a cool neb in NB...I went for her profile once again :thumbsup:

This is a Bi-Colour (Ha OIII) image with some RGB mixed in

I enjoyed some quite good seeing for the Ha but just average seeing for the OIII (did I mention I want to move to Chile? :sadeyes:)

Gabriela Mistral Nebula (http://www.pbase.com/image/154775029/original) NGC 3324 (Full Frame)

Close Up (http://www.pbase.com/strongmanmike2002/image/154764009/original) of the famous poets profile

100% Crop (http://www.pbase.com/strongmanmike2002/image/154789409/original) Halpha only

Here is an extreme close up (http://www.pbase.com/strongmanmike2002/image/154789844/original) comparison with Hubble

Hope the Bi-Colour colour scheme looks ok..?

As usual, No Darks, No Flats and No noise reduction :)

Mike

[cybereye]

Very nice indeed Mike! As I mentioned on Flickr, thanks for sharing what is on the other side of the clouds - it's always a tremendous pleasure! :thumbsup:

Cheers,
Mario

[alpal]

Nice shot Mike.
You've got a lot of detail in there.

cheers
Allan

[SkyViking]

Beautiful work there Mike. Did you consider lowering the intensity of the bright inner blue region? I think you'd get a really cool strong blue hue in there as a result, but I don't know how bright it really is compared to the rest so just an idea :)

[telecasterguru]

Quite striking.

Frank

[Stevec35]

Not quite sure I like the colour Mike but technically nice in every other respect.

Cheers

Steve

[Bassnut]

Youve done well their young Mike, lots of detail and appropriate saturated colour. Im not sure the bicolour thing worked though, even bad Sii would have made it a bit less bitonic. Im not sure why you dont use darks really, given they are easy to collect and last a good year if your lucky. They are stupid easy to apply during processing and would give you that slight less noise edge to allow more confidence in processing.

[strongmanmike]

No worries Mario and grazzie for your kind comments, it isn't everyone's cup of tea and often hard to please everybody :thumbsup:



Thanks Alan yes I was happy with the seeing on that night, see guide star centroid plot from a few sub sets across the night... and that certainly helped with the details :)



Thanks for the suggestion Rolo, I did try a few version incluidng making that aea darker but I may have another tinker...Arggg :scared: another Sidonio might be coming :eyepop: :lol:



Thanks Frank, glad to have struck you :)



No probs Steve, this narrowband thing is a little fickle and I did decide to miss the SII and only go Bi-Colour but don't think this object works with the traditional Red-Blue look that the Ha-OIII combo usually gives...? so I tweaked it with some layer mixing magic :D



Thanks Fred, yeah I hear the Botonic thing, I tried to counter that by tweaking the bi-colours with the RGB but in the end there are only two main data sets I guess and this was the outcome...?..I was happy with the nice blue OIII wisps in the fainter areas, remind me of floating thin cirrus :thumbsup: As for the darks?...As an older generation Kodak chip user it would be hard for you to understand but the Sony chip and in this particular camera architecture simply doesn't need them and in fact adding them (and/or flats and flat darks) is actually likely to make the noise level more :) ...I was quite happy with the noise level in this image though..?? :shrug: and that was with no noise reduction, just dithered lights and median combine.

[strongmanmike]

I had some good seeing the night I collected the Ha...so meah, I may as well have a look.....

Here is an extreme close up comparison with a Hubble crop (http://www.pbase.com/strongmanmike2002/image/154789844/original) just to verify the details visible

:)

Mike

[rat156]

Hi Mike,

It's a nice Gabriela for sure.

But I have to agree with Freddy a bit, it could be better.

I looked at the larger images and some of the stars (Top RHS of the Ha image) are a bit not round, they seem to be elongated in a diagonal way. I even put on my glasses to make sure it wasn't my eyes. As your seeing and guiding were good, perhaps there's been a misregistration. I find that CCDStack sometimes does this in very dense star fields.

The image doesn't need darks as you have dithered, so they'll be eliminated mathematically as long as you get enough subframes for the mathematical rejection to work. But it could be sharpened a bit. Louie Atalas has a great tutorial on using PS to do deconvolution. I tend to go a bit overboard WRT sharpening, but as long as you're not introducing stuff that isn't there then you're just correcting out the atmosphere.

Colour is the choice of the photographer in NB imaging. Even more so with bicolour. Look at mine (http://www.astrobin.com/full/76356/0/), those wisps of OIII have turned green because of the way I treated the Ha data.

We should compare Ha images. Essentially the same scope design, mostly the difference would be atmospheric, though I can't remember the weather when I took my Gabriela.

Cheers
Stu

[multiweb]

Great colors. I don't understand why you don't do flats or darks. Darks I never did with my QHY8 that wasn't temperature regulated but for sure flats are important to get rid of dust motes and uneven illumination. :shrug:

[SkyViking]

Hi Mike, I didn't notice noise in particular and your images with the new cam have all been great, so the following is purely from a theoretical point of view:

Why would darks introduce noise (unless you didn't have enough dark frames)?
And I'm wondering about flats too, because regardless of the chip you'll always have at least a degree of natural vignetting, due to the light rays striking the outer areas of the chip at an angle (pixel sensitivity depends on the angle of the incoming light). There will be dust doughnuts too, at least eventually.
Once you'ce created a dark/flat library there should be no extra effort required in applying this step to all your data. The calibration can be automatically applied in software like Maxim, so just thinking why wouldn't you always calibrate your data and squeeze the most from your camera?
So, not saying that your images need any of the above, but ideally I guess we'd all love to get the most from our equipment. :)

[strongmanmike]

Thanks Stu and great detailed reply :thumbsup:



Aint that always the truth :rolleyes: :lol:



Well, yes, I guess under extreme scrutiny almost any system will reveal something imperfect, in fact and even though it is not displayed at full res and to me it doesn't matter, the stars are not uniformly round in your shot either :shrug: nor in Rolfs if you look closely...it's the nature of our beasts ;) but it doesn't detract from the overall visual experience in my opinion, we can become way too fixated on optical perfection rather than imaging sometimes ;) Newtonians are indeed very hard to get absolutely perfect in all situations, especially fast ones, but never the less produce arguably superior sharper looking images to many RC's and certainly to SCT's, of significantly longer FL :)



Yes, agreed, hence why I don't need them given the low noise levels on the chip :D



Hey, perhaps you are right... but in the end it is a processing choice and the level of sharpening is usually an aesthetic choice in most cases rather than actually revealing real extra details without looking noisy. I did try sharpening more during processing of the main bi colour image (I worked out how to use the decon better in Astroart :clap: ) but yes, as you say with your version (sorry) it looked slightly "over" sharpened and didn't actually show any more real "features". I decided I liked it looking ever so slightly soft rather than super hard edged...all the same features are still there - again just a choice :thumbsup:.



That's it, nail on head Work Choices :D...:question:...:eyepop: argggg run for your liiiives, they are being brought back to life, dug-up and un-cremated :lol:



The seeing was pretty good for my Halpha :prey: :lol:

Thanks again for taking the time to make a worthwhile response :)

[strongmanmike]

I do agree about the flats but not the darks actually as I use dithering. There are indeed sensitivity variations across even this lovely Sony chip and yes probably some very slight optical brightness variations that flats might address but the flats and flat darks will add noise. Luckily I have no dust motes though, even under hard heavy stretch so at the moment at least flats are not required for these :D

In the end I think your first sentence there says it all Rolf :thumbsup:

I may of course buckle under all the pressure to conform...:question: :lol:

Mike

[RickS]

Great work, Mike. Love the details. The Hubble comparison shows you done good :thumbsup: The colours are OK but not entirely to my taste.

Cheers,
Rick.

[atalas]

Very nice Mike!

[strongmanmike]

Hey cheers Ricki :thumbsup:, the Hubble comparison is pretty bloody good for a 12" 1120mmFL F3.8 Newt for sure but it also shows me that I'd dearly love some longer focal length for these good nights :painting: hmmm? I neeed a system that can convert from F3.8 to about F6.8 or so...hmmm? Might have to splash out on an ASA 1.8X Barlow, they will work perfectly with the AG12 :thumbsup:

Mike

[strongmanmike]

Ahhh the "very nice" comment...ok, ok, so you are struggling with the colour palette I know :rolleyes: :lol:

Cheers mate :)

Mike

[atalas]

:lol: oh damn you tough sometimes mate! hehe

No,I actually love the color !

For the record : I prefer no sharpening at all If you achieve good focus on a good night!

I believe that contrast & color work will give you the edge(no punt intended) we are after....but everyone to their own I say! :thumbsup:

[strongmanmike]

Ohhh well hallelujah :prey2: :rofl:



Really?...no sharpening at all :question:...that's just gotta fly in the face of convention mate :shrug: it's...just gotta :shrug:...like not doing darks or flats :question: :lol:

Mike

[gregbradley]

Nice image Mike. Not my favourite of yours though. The colour is a bit weak (I'm talking about depth not how saturated or otherwise) compared to your normal. Pushed a bit hard?

Greg.

[strongmanmike]

Well...given I am not the best imager on this forum :question: :scared2: what did you expect? :lol:... ok sorry only my humour there, I think Martin was just tired, I know you get me :thumbsup:

Colour too strong, then colour too week...arrrg you drivin me crazy man :driving: :lol: no probs about being iffy about the colour, I only had two to play with essentially...maybe I'll get the third...and take darks..and flats :innocent:

Mike

[rat156]

Yeah, I have a tilt problem to sort out, the upper 1/4 of my images are hard to keep in focus, everything else is in focus, except the upper 1/4, shows up in the corners. You don't need full resolution to see it either. A problem to be sorted at another time, may require shimming something. I need to discover if it's in the camera/corrector or the focuser. Wanna lend me your scope??




What can I say, I like 'em sharp, although most of the time I'm sharpening for differential contrast, trying to make the black bits blacker. I'm OK with what it does to the noise. I'm constantly on the lookout for a method to treat the noise differently, it'll come in time and experimentation.






Yeah, the seeing was good for my place, but that's still not good by any reasonable measure. Looking at my data I might just do a Sidonio on it boost the contrast a bit and sharpen less. Always willing to learn. It's also cloudy and rainy here.

Always happy to critique your work Mike, it's the only way we get better. You can look at an image for days and not see a simple error that someone else picks up in seconds.

Cheers
Stu

[strongmanmike]

Oh I forgot too.. most of the slight irregularity you see in my star shapes in that 100% Ha crop is because (shock horror and don't tell anyone) I partially layered in a star minimised version, acting just on the stars, to shrink them a tad further than the 12nm Ha filter supplies, so under very close scrutiny, the faint stars especially, do have that slight skew-iff shape characteristic of the minimum filter...hopefully most casual eyes will miss it :)



Why? they have the same optical sets made by the same manufacturer (unless you went with Lomo?) but mine is Ultra Grade ;)...only the corrector is different..oh and your secondary spider is double, err? and my focuser base has extra inner and outer tube bracing and I have three cooling fans :D...but yours is black and Red :sadeyes:

Mike

[David Fitz-Henr]

A nice image Mike, and I hasten to add that the colour works well for me ;) The overall level of sharpening appears quite pleasing to my eye as well. I guess the perfect amount of sharpening would be that which compensates for the noise in the total system (incl. atmospherics / optical / read / shot / etc); no more, no less :shrug:

I'm not sure about flats introducing noise though; assuming that a reasonable number of flats are combined I would think that noise may be reduced, due to the slight variations in sensitivity between pixels. In other words, the noise introduced by the flat would be overwhelmed by the variation in pixel sensitivity (given also that there is high SNR for flat frames). I'd be interested in others opinions here :question:
Edit: Actually, upon looking at some flat subs my initial impressions appear incorrect, the variation in pixel value does not appear to be consistent even for high signal so is probably attributable to noise rather than pixel sensitivity after all ...

[strongmanmike]

Hey cheers Dave glad you weren't driven insane by the bi-clour palette :thumbsup:

Re flats, Terry Platt (owner of Starlightxpress) convinced me some time ago that with these Sony chips doing darks was very likely to only add noise and that dithering should be all that's practically necessary and my experience seems to confirm this. The avoidance of flats is more a personal desire and the smaller H694 chip and my large well illuminated field has largely let me get away without them and the associated noise introducing flat darks. However, this avoidance was definitely not the case with the ProLine 16803 of course and here I need darks, flats and flat darks for the usual reasons :thumbsup:

Mike

[Harel_Boren]

Wonderful, wonderful work !

Cheers,
Harel

[strongmanmike]

Hey, thanks Harel, I'm not the only one with a crazy retina :lol: :thumbsup:

Mike