M27 First go at AP with TEC 140

[kirkster501]

Been using the TEC so far mostly for visual but AP has been up and coming.  This was completely processed and prepocessed in Pixinsight.  Struggling to get the blackness of the sky right without clipping too much data - very diffiult to do!!!!

This is 45 mins L and 25 each on RGB.

Criques and comments welcome - that's how one learns!

[swag72]

Interesting to see how this scope copes with the smaller Sony Chips as there was quite a thread on CN saying that it didn't cope in the blue channel at all..... A nice FOV...... food for thought

[kirkster501]

The scope is parfocal with my Atik 460 and Baader LRGB filters.  I need to do more testing but I never refocused on the image above at any rate.

[ollypenrice]

It does seem that the flattener has a positive effect on the Sony chips, according to the thread Sara mentions. The issue was not one of parfocality but of colour correction in the shortest blue wavelengths. 

For me trying to process a whole image in PI would be like trying to mend a watch while wearing boxing gloves so I'm not sure I can offer any specific processing tips. However, I'd have a look at the colour balance in the background sky. It seems a little red to me and maybe a little bright. Given the shortish data and lack of Ha or OIII I'd say you are doing very well on the outer halo already. The main part of the nebula seems to me to lack contrast, though.

Olly

[kirkster501]

Thanks Olly.  The captured data is good, I need more of it though!   Ha included.  I need to learn a lot more about processing.

If anyone feels so inclined the xisf data file and where I have got so far is here (238Meg)

https://dl.dropboxusercontent.com/u/20949989/almost complete.xisf

 

[sloz1664]

Hi Steve,

Nice to see you are using the gorgeous Tec 140 and a miracle you are actually imaging in the poor skies we have had of late. Whenever I've had relatively decent skies it's been on a work day or a function evening.  The Halo really does show on your image. Yep a tad on the bright side, balancing the colours and darken it slightly may bring out the stars in the inner core and reduce the pink into more of a red.

Still a nice crisp image and certainly an image to build on.

Steve

[gnomus]

Steve

Terrific image.  Good to see some results from that scope at last.  Far be it for me and all that, but I wonder if you might just have overstretched things a tad - your background seems a bit on the bright side, and one or two the stars have odd little artefacts.  Also, are you quite sure you have the spacing correct between sensor and flattener?

Steve

[kirkster501]

5 hours ago, gnomus said:

Steve

Terrific image.  Good to see some results from that scope at last.  Far be it for me and all that, but I wonder if you might just have overstretched things a tad - your background seems a bit on the bright side, and one or two the stars have odd little artefacts.  Also, are you quite sure you have the spacing correct between sensor and flattener?

Steve

No flattener required Steve on my size chip on the Atik 460.  I still need to pop up and see the Mesu BTW!

[gnomus]

You would be very welcome Steve.  I managed to break it though! 

I dropped it off with Lucas a few days ago, however, and he tells me that he has already fixed it (I think it took him less than 30 mins).  I'll be pickng it up in a week or so.  

 

[PatrickGilliland]

Hi Steve

Great start to M27 just a couple of ideas and thoughts - hope some are at least useful.

Maybe my physics is askew (not my strongest subject) appreciate filters are parfocal but a refractor, even a good one is unlikely to be from my recollection, the lens refracts the light and R,G and B will have to converge/focus at different points as that is the mechanics of light, this may be what has caused some of the colour fringing on the stars  Might be a very small delta though and no significant.  Would be interested in hearing about when you have tested more.

On the clipping i think there is more to it than just the black point.  In fact i think there are two additional elements.  First if you look the background is more brown than black in tone, my guess is that the processing (and not adjusting black point earlier) has meant that colour has been added to the background and created the brown.  An earlier but controlled clip will prevent to much colouration, some is required but not too much.  Second before you do try a little noise reduction (use range selection in PI) just on the background.  Getting this cleaner will provide a much more defined histogram curve - if done correctly you will see histogram move with a steeper drop of point on the black side.  Noise reduction, desaturate a little if required and then process.  SOme HDMRT and LHE may also help adjust DSO and background levels allowing for easier HTT settings.

Thanks - Paddy