Orion - Taurus Widefield

[Macavity]

Orion-Taurus: Single 120s frame f/2.8 ISO 1600 24mm Pancake on EOS 100D.
"Brute Force" (v.rough!) processing to flatten the field. But intrigued to see if I
can extract better/cleaner images from STACK of 10 frames. Quite excited... 

Ignoring the colourful(!) artifacts in the corners, imagining what might be the
California Nebula at 11 o'clock to the Pleiades? Used Skywatcher Neodymium
filter, but thinking I might try e.g. Baader UHC filter to enhance nebulosity.  

[johnfosteruk]

Cracking image Chris, I think that is definitely California.

[Pete Presland]

Excellent image,  looks like that is definitely California to me as well.

[Macavity]

Thanks for your interest! As ever folks are (perhaps too?) KIND here.
But I am also intrigued re. the challenges of "extreme" widefield... 

As an indicator of "what I am up against", here's a single (jpeg) frame
of the region of interest  - with accompanying histogram (from GIMP)!

Yesterday (after much procrastination!) I finally got to grips with DSS.
I can now e.g. STACK 10 "raw" files of this ilk... AND subtract "darks"!
I know little about "offsets" but I am working on (artificial?) "flats"!

The most "obvious" problem is a significant *gradient* on the frame!
I speculate that I cannot do any better / worse via adjustment of the
exposure / f-stop / ISO once the histogram is reasonable "central"? 

In an IDEAL world, I would like to be able to image "Barnard's Loop"!
BUT maybe such is just not possible with an "un-modded" DSLR and
the sort of gradient and light pollution - As evidenced by the above? 

But maybe there is some *genius* out there who can point the way?
No obligation. "Give it up, Sunshine"(!), might also be a valid too...  

For what it's worth, a mere tentative application of *IRIS* software gradient
removal (I suspect it uses same algorithm as "Grandient Exterminator"?!?!)
reveals a significant improvement! (Note accompanying narrow histogram!)

And, if I cut (trivivially!) on the LEVELS histogram above:

WE can see the "California" neb (right, guys!). There is *some* evidence of the
"fainter stuff" But IT MAY BE that there is no more I can extract from this data?
But I still note a vague "red blob" around the "lambda orionis" (Meissa?).  

I am left both encouraged and frusterated! I could play with a *lot* of things...
Maybe the only solution is narrow band filtering! But technically rather harder!

(ANY) Thoughts welcome. Even if it's only: "Give it up, Sunshine! etc. etc.
Whatever! If I can vaguely inspire others to give random ideas a try... lol.

[happy-kat]

That lens isn't too bad it looks quite sensitive to pick up stars. Flats...flats will deal with the vignetting did you use it on a ff camera? Bias frames a lot easier to take then darks. I don't do darks anymore. Bias lens cap on same everything else but use fastest shhutter possible and bang out 50. Try startoools free trial the the wipe tool would get rid of that gradient.

[happy-kat]

For my flats I use app lightbox and hold my tablet up to and against the lens adjust only exposure length to get histogram in the middle and bang a load of those out. Light box slider is at about 60%.

[Macavity]

Thank you for BOTH the above, HK. It's ever good to ask?
(I enjoy hearing how others do things!) Fwiw, No, I couldn't
find substantial worth re. "Darks", but will think about Bias's!

I sense FLATS might ever be "fun" re. such wide fields (and
a bit of light pollution thrown in as well!). So I'm persuaded
that some viariant on the "light box" might be a good idea!

(Of course) my cute Canon 100D is not an "ff" (full frame?).
And I am just getting to grips with the thing generally too!
Good fun to find it still "better" than I might've magined.  

Thanks again...

[happy-kat]

Lightbox is (I think it was free) an application I got in the google play stoe it is in Apple to. It turns your tablet into a large white screen with an intensity slider for adjustment, it's my quick cheat to create flats to deal with the vigneting I just add it to the end of the session then I take the filter off (I have a lp one) and put lens cap on for bias frames, the latter are loaded as bias/offset frames in DSS. My 7 inch tablet easy covers the lens for flats as I (probaly doing it wrong but it works for me) hold it against lens so the area of screen needed is quite small I just line it uip to miss the air bubbles in my screen protector. All I need to a clear sky when I can actually get outside and use it getting rustier by the week on processing.