Rosette nebula in Ha

[swag72]

This is the first decent image that I have managed with my new Optec reducer thanks to an abundance of adaptors. Still need 1 more, but I am happy enough with this while I wait to absolutely nail the spacing.

This is the Pentax 75SDHF running at 352mm and f4.7 - I like both the speed and field of view. The speed has certainly got rid of any noise that is there at slower speeds.

Hoping to add some colour to this in the next few nights, I hope to have this as an image I'm happy with ultimately, but I doubt it!!!

15x1200s Ha with bias frames. Stacked and calibrated in PI and the rest done in PS. I welcome all types of criticism and comments on this - If you can see an issue or something I've missed then please do tell me.

[opticalpath]

That is absolutely brilliant, Sara! :icon_salut:

You've captured the faint outer stuff and kept the brighter bits well controlled ..... but also got great contrast (the selective sharpening is very nicely done) that really makes the image pop.

By coincidence, I've also been working this week on a Ha-RGB Rosette taken with the Pentax scope about a year ago, only 7 x 1200 sec at f/6.7; it fits on the 8300 chip with about the same FOV. I was quite pleased with it until I saw yours!

I'm sure it's going to make a great colour image when you capture the RGB. If it's any use to you in the meantime, please feel free to use this (lightly processed) RGB image that covers about the same fov. http://universalconstant.com/Rosette_Group2_RGB.tiff (11MB)

Adrian

[andyo]

Thats great Sara the detail is superb stars are pin sharp well done

[Steve 1962]

That's a stunner Sara - was it taken with the 460??

[Gina]

Really superb with great detail - excellent Sara

[swag72]

Thanks all - I've managed to collect some red and blue data so far, and there's hope for another clear night or two to collect some green. If I come unstuck I'll try your colour data Adrian, thank you.

Yes Steve, this was done with the 460EX - Best image I think Ive managed with it. The speed of the scope makes a really considerable difference I think.

[Martin-Devon]

Lovely image Sara - as others have noted, you've processed it very well indeed, just the right level really - it's so easy to over-process the Rosette. Any reason why your colour version will be an Ha-LRGB as opposed to a full narrowband colour? Maybe just a preference choice since both colour outputs look very nice. Look forward very much to the final full colour image though, the Ha layer you have there at the moment is superb!

Martin

[TakMan]

Looks good Sara - at least all the effort was now worth it!

I also think this looks less noisy (compared to your previous post where that was mentioned with regards to the Atik 460EX), so that's good news also - although I still think there is an underlying 'noise' pattern?

I'm surprised to say/see this, as I would have thought 15x 20min exposures would have really started to tame it more. Certainly at around 16+ exposures the noise in the 'noisy' 8300 chip starts to dissipate. Is it a processing/sharpening issue do you think or just the chip...?

At about 85% out you are starting to see the slight elongation of stars - so a very decent result after all your hassles (which you should improve upon with the final spacer). At least it looks 'symmetrical' (to me anyway), so you know that the focal plane is level.

As Adrian and Martin mentioned, the processing though is very complementary - the Bok Globules look particularly striking.

Sounds like someone's been getting some decent weather!

Clear skies and 'spacer playing'!!!!,

Damian

[Coco]

Looks fab to me Sara , you must be really pixel peeping to want to improve further unless you have cropped out the poorest parts?

I love the sharpness and detail, great job.

[VigdisVZ]

Wow. Images like these make me want to run out and get a CCD and a frac right away.

[swag72]

Thanks Guy and Carl and Damian for your detailed reply - Can you point to where you see an underlying noise pattern? I don't use darks, but perhaps I'll redo the bias. Or would a pixel map work well for this type of noise?

The spacing has been a pain in the backside, but after a further play just now, I have the spacing to within +/- 0.1mm of the recommended figure. I hope that this will sort out that rough corner that I have. I've not cropped out anything Guy, this is exactly as is and yes, I am a bit of a pixel peeper!!

I hope that this is the last play with the spacing now as it's doing my head in!! If this has sorted it out, I will be amazed that about 1mm makes so much difference.

[opticalpath]

I'm looking forward to seeing your colour image of this Sara.

Have you found a good way of dealing with the blue-bloating of brighter stars that is the one weakness of the Pentax scope when doing RGB? There are quite a few troublesome stars in the Rosette that are affected.

I usually resort to cosmetic cover-up repairs but I wish there was a better way - you end up in effect throwing away some of the blue flux and that must upset the colour balance. Some kind of deconvolution that would reconstitute the blue signal in a smaller PSF would be the answer but I haven't found a way yet of using the usual decon filters to do a good job of it. I wondered if you'd found a better way?

Adrian

[swag72]

You mean my scope isn't perfect? Don't tell me that now!! As I've yet to process a colour image, when I do I'll probably get myself in a right old tizz! Decon absolutely not tried at all, something along with PSF that I don't underdtand and so avoided like the plague. Maybe I'll just resort to my usual method of cloning!! We'll see how it goes!

[stellawolf]

Hi Sara great image well done

[saturn5]

Stunning detail,a superb image.

[TakMan]

Hi Sara - Yep, I'm a 'pixel peeper' also!

Perhaps it's just me - I'm critical, have to be as part of my job (running a graphics dept) and believe me I can see more than enough 'issues' in my own shots .... but you did ask for feedback...!

The chip/camera though is also one I'm looking at - or possibly holding off for an even bigger variant, so I'm interested to know your thoughts. Especially so, as the QE curves for this chip are far better than that of my own camera and the smaller pixels would offer even better resolution. Then you mentioned a possible 'noise' issue in a previous post......

Still a great shot - and definitely a 'lift' for you after all the spacer issues...

I went back to your highest res version on Flicker and downloaded it. I've tried to highlight what I am 'seeing'... is it from just the re-sizing to the web, the file conversion.... pre-processing, inherent noise, a form of sharpening artefact or a lack of control frames.... or just me!

Regards,

Damian

[opticalpath]

You mean my scope isn't perfect? Don't tell me that now!!

Naw, don't panic . It only seems to affect the brightest stars. Clone tool works for me - I just wondered if you'd found a better way.

Adrian

[swag72]

Thanks Damian. I really do appreciate you looking and commenting and certainly do value criticism of any type as it's the only way to improve in my eyes. Thanks for taking the time to look so closely for me. I'll go back to the full res tiff later and see if I can see what you've highlighted. I think though I'm going to have to stop pixel peeping, it's really soul destroying!!

Adrain, you are very bad for bringing that to my attention!!! But I think you've calmed my fear again!!!!

[steppenwolf]

This is a really nice image, Sara and I'm pleased that you have essentially nailed the spacing at last - it shouldn't be this difficult should it!

[Zul]

Fantastic image!

[swag72]

Thanks Steve and Zul - You are right, it shouldn't be this difficult!!

This data has been combined into my colour Rosette that can be seen below and also in another thread. I've sorted out some red star issues in the nebula and feel it's made a difference.

Rosette nebula (NGC2237) by swag72, on Flickr

[stem1989]

stunning, stunning detail. great image

[swag72]

Thank you!!

[StuartJPP]

Stunning detail Sara!

[swag72]

Thanks Stuart!