Canon DSLR: Cone Nebula in H-alpha-RGB composite

[Christoph Puetz]

Dear PI Community,

again I tried to bring my DSLR to its limits  .
I used a 6" / f=1100 mm Starfire refractor with reducer/flattener and took the following frames
with a modfified Canon EOS 450d

09.11.2011
17 frames x300 sec, 1600 ASA, 12nm H-alpha EOS Clip Filter = 85 minutes (moonlight!)
20 Darkframes

15.11.2011
41frames x180 sec, 1600 ASA, 12nm H-alpha EOS Clip Filter = 123 minutes (moonlight)
20 Darkframes

20.11.2011
39frames x300 sec, 1600 ASA, CLS EOS Clip Filter = 195 minutes (no disturbing moonlight)
25 Darkframes

Sum: 97 frames, total 403 minutes exposure time = 6h 43 min

All frames were fully processed with the current PI version.
Esp the following functions were necessary :
- Alignment of single frames for each foto-Session
- realignment before composite
- ABE
- HDR Wavelet with and without median transformation, best results on (linear) layers 3-5
- deconvolution in order to get stars sharper (after masking the non-stellar objects)
- ACDNR Filter the reduce chromatic noise esp in the H-alpha frames
- LRGB Composition with the following channels:

L => Luminance from RGB result (intensively sharpened by wavelets)
R => red channel of resulting H-alpha frame (intensively sharpened by wavelets)
G => green channel of resulting RGB frame
B => blue channel of resulting RGB frame

The resulting foto was again filtered against chromatic noise (within the LRGB function)
and the background was slightly filtered by the Greycstoration algorithm (with a lot trial and error) ...


So - this was quite a long way to go and also a lot of possible ways to make it better 
There is still some noise visible ...
Therefore - any feedback and hints for improvement are welcome, always pleased to learn !!

[medium resolution]
http://www.ccdsky.eu/Astronomy/slides/k-konus_ha_rgb_v3_greycstoration.html

[FLICKR, labeled]
http://www.flickr.com/photos/cpfoto1964/6384339253

Kind regards and clear skies !
Christoph

[Lex]

Hi Christoph,

Nice work! I like your image and the object!

[zvrastil]

Hi Christoph,

this is quite an achievement for DSLR!

Two notes on the processing:

1) I would not use ABE for this kind of image. ABE is great for images of small galaxies, planetary nebulae or clusters. But here, faint nebulae are scattered on almost every part of the image. I'm pretty sure you can't avoid ABE to take away some of the faint stuff. I'd recommend DBE with small number of samples carefully placed in darkest parts, possibly on heavily stretched and color-saturated copy of the image (and then process-applied on the original image). Rogelio has an excellent tutorial on this topic: http://blog.deepskycolors.com/archivo/2010/05/28/removing-gradients-while-preserving-ve.html

2) I'd try to do noise reduction on linear image using ATWT. To my experience, this gives results superior to ACDNR. With ACDNR, I almost always end up with small-scale noise converted to large-scale noise (ugly "blobs" in the background). I can see the same pattern in dark areas of your image. ATWT noise reduction tends to give me much better results.

best regards, Zbynek

[Christoph Puetz]

Dear lex and zvrastil,

thanks very much for your replies and valuable hints. In fact, the tutorial of Rogelio and your
suggestions for noise reduction will help me going on !

[astropixel]

Lots of data there and a nice image to boot...

2) I'd try to do noise reduction on linear image using ATWT. To my experience, this gives results superior to ACDNR. With ACDNR, I almost always end up with small-scale noise converted to large-scale noise (ugly "blobs" in the background). I can see the same pattern in dark areas of your image. ATWT noise reduction tends to give me much better results.

Agreed. ATWT at the linear stage is very effective on DSLR images - and periodically throughout non-linear.

I have just finished modifying my DSLR with an Astrodon Inside filter. If that's the result after only 2+ hours I cant wait for a clear night.

[Christoph Puetz]

Hi Astropixel,

welcome to the DSLR enthusiasts - let's exchange our experiences and images regularly ! 

[astropixel]

Will do Christoph. It has been cloudy for more than 2 months!!!